10-K

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-K

(Mark One)

☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the fiscal year ended December 31, 2019

or

☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

Commission file number: 000-51026

Monolithic Power Systems, Inc.

(Exact name of registrant as specified in its charter)

Delaware	77-0466789
(State or other jurisdiction of incorporation or organization)	(I.R.S. Employer Identification Number)

5808 Lake Washington Blvd. NE, Kirkland, Washington 98033

(Address of principal executive offices)(Zip Code)

  (425) 296-9956

(Registrant’s telephone number, including area code)

Securities registered pursuant to Section 12(b) of the Act:

Title of each class	Trading Symbol	Name of each exchange on which registered
Common Stock, par value $0.001 per share	MPWR	The NASDAQ Global Select Market

Securities registered pursuant to Section 12(g) of the Act: None

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act. Yes  ☒   No  ☐ 

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act. Yes  ☐   No  ☒

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days.    Yes  ☒    No  ☐

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Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§ 232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files).     Yes  ☒  No  ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

Large accelerated filer ☒	Accelerated filer ☐
Non-accelerated filer ☐	Smaller reporting company ☐
	Emerging growth company ☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Act). ☐ Yes   ☒ No

The aggregate market value of the voting and non-voting common equity held by non-affiliates of the registrant, based upon the closing price of the common stock on the Nasdaq Global Select Market on June 28, 2019, was $4.3 billion.*

There were 44,602,000 shares of the registrant’s common stock issued and outstanding as of February 19, 2020.

DOCUMENTS INCORPORATED BY REFERENCE

Portions of the registrant’s Proxy Statement for the registrant’s 2020 Annual Meeting of Stockholders are incorporated by reference into Part III of this Annual Report on Form 10-K where indicated.  The Proxy Statement will be filed with the Securities and Exchange Commission within 120 days of the registrant’s fiscal year ended December 31, 2019.  

* Excludes 11,709,000 shares of the registrant’s common stock held by executive officers, directors and stockholders whose ownership exceeds 5% (“affiliates”) of the common stock outstanding at June 28, 2019.  Exclusion of such shares should not be construed to indicate that any such person possesses the power, direct or indirect, to direct or cause the direction of the management or policies of the registrant or that such person is controlled by or under common control with the registrant. 

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MONOLITHIC POWER SYSTEMS, INC.

TABLE OF CONTENTS

		Page
PART I
Item 1.	Business	5
	Information about Executive Officers	9
Item 1A.	Risk Factors	9
Item 1B.	Unresolved Staff Comments	26
Item 2.	Properties	27
Item 3.	Legal Proceedings	27
Item 4.	Mine Safety Disclosures	27
PART II
Item 5.	Market for Registrant's Common Equity, Related Stockholder Matters and Issuer Purchases of Equity Securities	28
Item 6.	Selected Financial Data	29
Item 7.	Management's Discussion and Analysis of Financial Condition and Results of Operations	30
Item 7A.	Quantitative and Qualitative Disclosures About Market Risk	39
Item 8.	Financial Statements and Supplementary Data	41
Item 9.	Changes in and Disagreements with Accountants on Accounting and Financial Disclosure	78
Item 9A.	Controls and Procedures	78
Item 9B.	Other Information	78
PART III
Item 10.	Directors, Executive Officers and Corporate Governance	79
Item 11.	Executive Compensation	79
Item 12.	Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters	79
Item 13.	Certain Relationships and Related Transactions, and Director Independence	79
Item 14.	Principal Accounting Fees and Services	79
PART IV
Item 15.	Exhibits, Financial Statement Schedules	80
Item 16.	Form 10-K Summary	82
	Signatures	83

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FORWARD-LOOKING STATEMENTS

This Annual Report on Form 10-K contains forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended, that have been made pursuant to and in reliance on the provisions of the Private Securities Litigation Reform Act of 1995. These statements include, among others, statements concerning:
 

• the above-average industry growth of product and market areas that we have targeted,

• our plan to increase our revenue through the introduction of new products within our existing product families as well as in new product categories and families,

• our belief that we may incur significant legal expenses that vary with the level of activity in each of our current or future legal proceedings,

• the effect that liquidity of our investments has on our capital resources,

• the continuing application of our products in the computing and storage, automotive, industrial, communications and consumer markets,

• estimates of our future liquidity requirements,

• the cyclical nature of the semiconductor industry,

• protection of our proprietary technology,

• business outlook for 2020 and beyond,

• the factors that we believe will impact our business, operations and financial condition, as well as our ability to achieve revenue growth,

• the percentage of our total revenue from various end markets,

• our ability to identify, acquire and integrate the companies, businesses and products that we acquire and achieve the anticipated benefits from such acquisitions,

• the impact of the U.S. Tax Cuts and Jobs Act enacted in December 2017 (the “2017 Tax Act”) and other tax laws on our income tax provision, financial position and cash flows,

• our plan to repatriate cash from our subsidiary in Bermuda,

• our intention and ability to pay future cash dividends and dividend equivalents, and

• the factors that differentiate us from our competitors.

In some cases, words such as “would,” “could,” “may,” “should,” “predict,” “potential,” “targets,” “continue,” “anticipate,” “expect,” “intend,” “plan,” “believe,” “seek,” “estimate,” “project,” “forecast,” “will,” the negative of these terms or other variations of such terms and similar expressions relating to the future identify forward-looking statements. All forward-looking statements are based on our current outlook, expectations, estimates, projections, beliefs and plans or objectives about our business and our industry. These statements are not guarantees of future performance and are subject to risks and uncertainties. Actual events or results could differ materially and adversely from those expressed in any such forward-looking statements. Risks and uncertainties that could cause actual results to differ materially include those set forth throughout this Annual Report on Form 10-K and, in particular, in the section entitled “Item 1A. Risk Factors.” Except as required by law, we disclaim any duty to, and undertake no obligation to, update any forward-looking statements, whether as a result of new information relating to existing conditions, future events or otherwise or to release publicly the results of any future revisions we may make to forward-looking statements to reflect events or circumstances after the date hereof or to reflect the occurrence of unanticipated events. Readers are cautioned not to place undue reliance on such statements, which speak only as of the date of this Annual Report on Form 10-K. Readers should carefully review future reports and documents that we file from time to time with the Securities and Exchange Commission (“SEC”), such as our Annual Reports on Form 10-K, Quarterly Reports on Form 10-Q and any Current Reports on Form 8-K. 

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Except as the context otherwise requires, the terms “Monolithic Power Systems,” “MPS,” “Registrant,” “Company,” “we,” “us,” or “our” as used herein are references to Monolithic Power Systems, Inc. and its consolidated subsidiaries.

PART I

ITEM 1.    BUSINESS

General

Monolithic Power Systems (“MPS”) is a leading semiconductor company that designs, develops and markets high-performance power solutions. Incorporated in 1997, MPS’s core strengths include deep system-level and applications knowledge, strong analog design expertise and innovative proprietary process technologies. These combined strengths enable MPS to deliver highly integrated monolithic products that offer energy efficient, cost-effective, easy-to-use solutions for systems found in computing and storage, automotive, industrial, communications and consumer applications. MPS’s mission is to reduce total energy consumption in its customers’ systems with green, practical and compact solutions.

Our principal executive office is located in Kirkland, Washington. We have over 2,000 employees worldwide, with locations in Asia (primarily in China, India, Japan, Korea, Singapore and Taiwan), Europe (primarily in France, Germany, Spain, Switzerland and the United Kingdom), and the United States.

Industry Overview

Semiconductors comprise the basic building blocks of electronic systems and equipment. Within the semiconductor industry, components can be classified either as discrete devices, such as individual transistors or integrated circuits (“ICs”), in which a number of transistors and other elements are combined to form a more complicated electronic circuit. ICs can be further divided into three primary categories: digital, analog, and mixed-signal. Digital ICs, such as memory devices and microprocessors, can store or perform arithmetic functions on data that is represented by a series of ones and zeroes. Analog ICs, in contrast, handle real world signals such as temperature, pressure, light, sound, or speed. In addition, analog ICs also perform power management functions, such as regulating or converting voltages, for electronic devices. Mixed-signal ICs combine digital and analog functions onto a single chip and play an important role in bridging real world to digital systems.

Analog and Mixed-Signal Markets.  We focus on the market for high performance analog and mixed-signal ICs. High performance products generally are differentiated by functionality and performance factors, which include integration of higher levels of functionality onto a single chip, greater precision, higher speed and lower heat and noise. There are several key factors that distinguish the analog and mixed-signal IC markets from digital IC markets. These factors include longer product life cycles, numerous market segments, technology that is difficult to replicate, relative complexity of design and process technology, importance of experienced design engineers, lower capital requirements and diversity of end markets.  We have targeted product and market areas that we believe have the ability to offer above-average growth over the long term compared to the semiconductor industry as a whole.

End Markets and Applications

We design and develop our products for the computing and storage, automotive, industrial, communications and consumer markets, with the computing and storage market representing the largest portion of our revenue in 2019. The following table is a summary of the various end market applications for our products, and those markets’ contribution as a percentage of our total revenue: 

		Percentage of Total Revenue
End Markets	Applications	2019			2018			2017
Computing and storage	Storage, computers and notebooks, printers, servers and workstations		30.1	%		27.3	%		21.4	%
Automotive	Infotainment, safety and connectivity applications		14.4	%		13.8	%		11.4	%
Industrial	Power sources, security, point-of-sale systems, smart meters and other industrial equipment		15.8	%		15.2	%		13.4	%
Communications	Networking and telecommunication infrastructure, routers and modems, wireless access points and voice over IP		13.5	%		12.1	%		13.5	%
Consumer	Set-top boxes, monitors, gaming, lighting, chargers, home appliances, cellular handsets, digital video players, GPS, televisions, stereos and cameras		26.2	%		31.6	%		40.3	%

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Product Families

Our proprietary process technologies enable us to design and deliver smaller, single-chip power management ICs. These technologies simplify the design process, and are applicable across a wide range of analog applications within the computing and storage, automotive, industrial, communications and consumer markets. Our product families are differentiated with respect to their high degree of integration and strong levels of accuracy and efficiency, making them cost-effective relative to many competing solutions. Our key product families include the following:

Direct Current (“DC”) to DC Products. DC to DC ICs are used to convert and control voltages within a broad range of electronic systems, such as portable electronic devices, wireless LAN access points, computers, and monitors, automobiles and medical equipment. We believe that our DC to DC products are differentiated in the market, particularly with respect to their high degree of integration, high voltage operation, high load current, high switching speed and small footprint. These features are important to our customers as they result in fewer components, a smaller form factor, more accurate regulation of voltages, and, ultimately, lower system cost and increased reliability through the elimination of many discrete components and power devices. The DC to DC product family accounted for 94%, 92% and 92% of our total revenue in 2019, 2018 and 2017, respectively. 

Lighting Control Products. Lighting control ICs are used in backlighting and general illumination products. Lighting control ICs for backlighting are used in systems that provide the light source for LCD panels typically found in notebook computers, monitors, car navigation systems and televisions. Backlighting solutions are typically either white light emitting diode lighting sources or cold cathode fluorescent lamps. The Lighting Control product family accounted for 6%, 8% and 8% of our total revenue in 2019, 2018 and 2017, respectively.

In the future, we plan to continue to introduce additional new products within our existing product families, as well as expand our newer product families. Our ability to achieve revenue growth will depend in part upon our ability to enter new market segments, gain market share, grow in regions outside of China, Taiwan and other Asian markets, expand our customer base and continue to secure manufacturing capacity.

Customers, Sales and Marketing

We sell our products through third-party distributors, value-added resellers and directly to original equipment manufacturers (“OEMs”), original design manufacturers (“ODMs”), and electronic manufacturing service (“EMS”) providers. Our third-party distributors are subject to distribution agreements with us, which allow the distributors to sell our products to end customers and other resellers, including OEMs, ODMs or EMS providers.  Our value-added resellers may second source our products and provide other services to customers. ODMs typically design and manufacture electronic products on behalf of OEMs, and EMS providers typically provide manufacturing services for OEMs and other electronic product suppliers.  

Sales to our largest distributor accounted for 23% of our total revenue in 2019, 22% in 2018, and 17% in 2017. In addition, one other distributor accounted for 10% of our total revenue in 2018 and one other distributor accounted for 10% of our total revenue in 2017. No other distributors or end customers accounted for more than 10% of our full-year, total revenue in any of the periods presented.

Current distribution agreements with several of our major distributors provide that each distributor has the non-exclusive right to sell and use its best efforts to promote and develop a market for our products. These agreements provide that payment for purchases from us will generally occur within 30 to 60 days from the date of invoice. In addition, we allow for limited stock rotation in certain agreements.

We have sales offices located in China, India, Japan, Korea, Singapore, Taiwan, the United States and throughout Europe. Our products typically require a highly technical sales and applications engineering effort where we assist our customers in the design and use of our products in their application. We maintain a staff of applications engineers who work directly with our customers’ engineers in the development of their systems’ electronics containing our products.

Because our sales are primarily billed and payable in United States dollars, our sales are generally not subject to fluctuating currency exchange rates. However, because a majority of our revenue is attributable to sales to customers in Asia, changes in the relative value of the dollar may create pricing pressures for our products. For the years ended December 31, 2019, 2018 and 2017, our revenue from sales to customers in Asia was 89%, 88% and 89%, respectively.

Our sales are made primarily pursuant to standard individual purchase orders. Our backlog consists of orders that we have received from customers which have not yet shipped. Because orders in backlog are subject to cancellation or postponement, and backlog at any particular date is not necessarily representative of actual sales for any succeeding period, we believe that our backlog is not necessarily a reliable indicator of future revenue.

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Our manufacturing lead times are generally 8 to 16 weeks and we often build inventory in advance of customer orders based on our forecast of future customer orders. This subjects us to certain risks, most notably the possibility that sales will not meet our forecast, which could lead to inventories in excess of demand. If excess inventory exists, it may be necessary for us to sell it at a substantial discount, take a significant write-down or dispose of it altogether, all of which would negatively affect our profit margins. In addition, in response to market conditions, we may slow the rate of manufacturing our products, which could result in insufficient inventory levels if we underestimate the demand for our products.

We operate in the cyclical semiconductor industry where there is seasonal demand for certain of our products. While we are not immune from current and future industry downturns, we have targeted product and market areas that we believe have the ability to offer above average industry performance over the long term.

Research and Development

We have assembled a qualified team of engineers primarily in China, Spain, Taiwan and the United States, with core competencies in analog and mixed-signal design. Through our research and development efforts, we have developed a collection of intellectual property and know-how that we are able to leverage across our products and markets. These include the development of high efficiency power devices, the design of precision analog circuits, expertise in mixed-signal integration and the development of proprietary semiconductor process technologies.

Our research and development efforts are generally targeted at three areas: systems architecture, circuit design and implementation, and process technology. In the area of systems architecture, we are exploring new ways of solving our customers’ system design challenges and are investing in the development of systems expertise in new markets and applications that align well with our core capabilities. In the area of circuit design and implementation, our initiatives include expanding our portfolio of products and adding new features to our products. In the area of process technology, we are investing research and development resources to provide leading-edge analog power processes for our next generation of integrated circuits. Process technology is a key strategic component to our future growth. 

Patents and Intellectual Property Matters

We rely on our proprietary technologies, which include both our proprietary circuit designs for our products and our proprietary manufacturing process technologies. Our future success and competitive position depend in part upon our ability to obtain and maintain protection of our proprietary technologies.

In general, we have elected to pursue patent protection for aspects of our circuit and device designs that we believe are patentable and to protect our manufacturing process technologies by maintaining those process technologies as trade secrets. As of December 31, 2019, we had 1,162 patents/applications issued or pending, of which 419 patents have been issued in the United States. Our issued patents are scheduled to expire at various times through December 2039. Our patents are material to our business, but we do not rely on any one particular patent for our success. We also rely on a combination of nondisclosure agreements and other contractual provisions, as well as our employees’ commitment to confidentiality and loyalty, to protect our technology, know-how and processes. We also seek to register certain of our trademarks as we deem appropriate. We have not registered any of our copyrights and do not believe registration of copyrights is material to our business. Despite precautions that we take, it may be possible for unauthorized third parties to copy aspects of our current or future technology or products or to obtain and use information that we regard as proprietary. There can be no assurance that the steps we take will be adequate to protect our proprietary rights, that our patent applications will lead to issued patents, that others will not develop or patent similar or superior products or technologies, or that our patents will not be challenged, invalidated or circumvented by others. Furthermore, the laws of the countries in which our products are or may be developed, manufactured or sold may not protect our products and intellectual property rights to the same extent as laws in the United States. Our failure to adequately protect our proprietary technologies could materially harm our business.

The semiconductor industry is characterized by frequent claims of infringement and litigation regarding patent and other intellectual property rights. Patent infringement is an ongoing risk, in part because other companies in our industry could have patent rights that may not be identifiable when we initiate development efforts. Litigation may be necessary to enforce our intellectual property rights, and we may have to defend ourselves against infringement claims. Any such litigation could be very costly and may divert our management resources. Further, we have agreed to indemnify certain of our customers and suppliers in some circumstances against liability from infringement by our products. In the event any third party were to make an infringement claim against us or our customers, we could be enjoined from selling selected products, could be required to indemnify our customers or suppliers, or could pay royalties or other damages to third parties. If any of our products are found to infringe and we are unable to obtain necessary licenses or other rights on acceptable terms, we would either have to change our product so that it does not infringe or stop making the infringing product, which could have a material adverse effect on our operating results, financial condition and cash flows.

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Manufacturing

We utilize a fabless business model, working with third parties to manufacture and assemble our ICs. This fabless approach allows us to focus our engineering and design resources on our strengths and to reduce our fixed costs and capital expenditures. In contrast to many fabless semiconductor companies, which utilize standard process technologies and design rules established by their foundry partners, we have developed our own proprietary process technologies and collaborate with our foundry partners to install our technologies on their equipment in their facilities for use on our behalf. This close collaboration and control over the manufacturing process has historically resulted in favorable yields and product performance for our ICs.

We currently contract with six suppliers to manufacture our wafers in foundries located in China and Korea. Once our silicon wafers have been produced, they are shipped to our facility in Chengdu, China for wafer sort, which is a testing process performed to identify non-functioning dies. Our semiconductor products are then assembled and packaged by independent subcontractors in China and Malaysia. The assembled ICs are then sent either for final testing at our Chengdu facility, or to other turnkey providers who perform final testing based on our standards prior to shipping to our customers.

We have a 60,000 square-foot manufacturing facility located in Chengdu, China, which enables us to benefit from shorter manufacturing cycle times and lower labor and overhead costs. We have expanded our product testing capabilities in this facility and are able to take advantage of the rich pool of local engineering talent to expand our manufacturing support and engineering operations.

Key Personnel and Employees

Our performance is substantially dependent on the performance of our executive officers and key employees. Due to the relative complexity of the design of our analog and mixed-signal ICs, our engineers generally have more years of experience and greater circuit design aptitude than the more prevalent digital circuit design engineer does. Analog engineers with advanced skills are limited in number and difficult to replace. The loss of the services of key officers, managers, engineers and other technical personnel would materially harm our business. Our future success will depend, in part, on our ability to attract, train, retain, and motivate highly qualified technical and managerial personnel. We may not be successful in attracting and retaining such personnel. Our employees are not represented by a collective bargaining organization, and we have never experienced a work stoppage or strike. Our management considers employee relations to be good. As of December 31, 2019, we employed 2,002 employees primarily located in Asia, Europe and the United States, compared with 1,737 employees as of December 31, 2018.

Competition

The analog and mixed-signal semiconductor industry is highly competitive, and we expect competitive pressures to continue. Our ability to compete effectively and to expand our business will depend on our ability to continue to recruit both applications engineering and design engineering personnel, our ability to introduce new products, and our ability to maintain the rate at which we introduce these new products. Our industry is characterized by decreasing average selling prices over the life of a product. We compete with domestic and international semiconductor companies, many of which have substantially greater financial and other resources with which to pursue engineering, manufacturing, marketing, and distribution of their products and, in some cases, have a broader number of product offerings that may enable them to more effectively market and sell to customers. We are in direct and active competition, with respect to one or more of our product lines, with at least ten manufacturers of such products, of varying size and financial strength. We consider our primary competitors to include Analog Devices, Infineon Technologies, Maxim Integrated Products, NXP Semiconductors, ON Semiconductor, Power Integrations, Renesas Electronics, ROHM Semiconductor, Semtech and Texas Instruments.

We expect continued competition from existing competitors as well as competition from new entrants into the semiconductor market. We believe that we are competitive in the markets in which we sell, particularly because our ICs typically are smaller in size, are highly integrated, possess higher levels of power management functionalities and achieve high performance specifications at lower price points than most of our competition. However, there is no assurance that our products will continue to compete favorably or that we will be successful in the face of increasing competition from new products and enhancements introduced by existing competitors or new companies entering this market. In addition, there has recently been a high level of consolidation in the semiconductor industry. If these or future acquisitions are successful, competition may intensify and our competitors may have additional resources to compete against us.

Available Information

Our Annual Reports on Form 10-K, Quarterly Reports on Form 10-Q, current reports on Form 8-K, and amendments to those reports that are filed or furnished pursuant to Sections 13(a) or 15(d) of the Securities Exchange Act of 1934, as amended, are available free of charge. They may be obtained from our website at www.monolithicpower.com under “Investor Relations” as soon as reasonably practicable after we electronically file such documents with, or furnish them to, the SEC or at the SEC website at www.sec.gov. Information contained on our website is not a part of this Annual Report on Form 10-K.

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Information About Executive Officers

Information regarding our executive officers as of February 28, 2020 is as follows:

Name	Age	Position
Michael Hsing	60	President, Chief Executive Officer and Director
Bernie Blegen	62	Vice President and Chief Financial Officer
Deming Xiao	57	President of Asia Operations
Maurice Sciammas	60	Senior Vice President of Worldwide Sales and Marketing
Saria Tseng	49	Vice President, Strategic Corporate Development, General Counsel and Corporate Secretary

Michael Hsing has served on our Board of Directors and has served as our President and Chief Executive Officer since founding MPS in August 1997. Prior to founding MPS, Mr. Hsing was a Senior Silicon Technology Developer at several analog IC companies, where he developed and patented key technologies, which set new standards in the power electronics industry. Mr. Hsing is an inventor on numerous patents related to the process development of bipolar mixed-signal semiconductor manufacturing. Mr. Hsing holds a B.S.E.E. from the University of Florida.

Bernie Blegen has served as our Chief Financial Officer since July 2016 and is responsible for finance, accounting, tax, treasury and investor relations. From August 2011 to June 2016, Mr. Blegen served as our Corporate Controller. Prior to joining MPS, Mr. Blegen held a number of executive finance and accounting positions for other publicly traded technology companies, including Xilinx, Inc. and Credence Systems. Mr. Blegen holds a B.A. from the University of California, Santa Barbara.

Deming Xiao has served as our President of Asia Operations since January 2008. Since joining us in May 2001, Mr. Xiao has held several executive positions, including Foundry Manager and Senior Vice President of Operations. Before joining MPS, from June 2000 to May 2001, Mr. Xiao was Engineering Account Manager at Chartered Semiconductor Manufacturing, Inc. Prior to that, Mr. Xiao spent six years as the Manager of Process Integration Engineering at Fairchild Imaging Sensors. Mr. Xiao holds a B.S. in Semiconductor Physics from Sichuan University, Chengdu, China and an M.S.E.E. from Wayne State University.

Maurice Sciammas has served as our Senior Vice President of Worldwide Sales and Marketing since 2007. Mr. Sciammas joined MPS in July 1999 and served as Vice President of Products and Vice President of Sales (excluding greater China) until he was appointed to his current position. Before joining MPS, he was Director of IC Products at Supertex from 1990 to 1999. He has also held positions at Micrel, Inc. He holds a B.S.E.E. degree from San Jose State University.

Saria Tseng has served as our Vice President, General Counsel and Corporate Secretary since 2004 and additionally as our Vice President, Strategic Corporate Development since 2009. Ms. Tseng joined the Company from MaXXan Systems, Inc., where she was Vice President and General Counsel from 2001 to 2004. Previously, Ms. Tseng was an attorney at Gray Cary Ware & Freidenrich, LLP and Jones, Day, Reavis & Pogue. Ms. Tseng is a member of the state bar in both California and New York and is a member of the bar association of the Republic of China (Taiwan). Ms. Tseng currently serves on the Board of Directors of Super Micro Computer, Inc., a global leader in high performance server technology. Ms. Tseng holds Masters of Law degrees from the University of California at Berkeley and the Chinese Culture University in Taipei.

ITEM 1A. RISK FACTORS

Our business involves numerous risks and uncertainties. You should carefully consider the risks described below, together with all of the other information in this Annual Report on Form 10-K and other filings with the SEC in evaluating our business. If any of the following risks actually occur, our business, financial condition, operating results, and growth prospects would likely be materially and adversely affected. In such an event, the trading price of our common stock could decline, and you could lose all or part of your investment in our common stock. Our past financial performance should not be considered to be a reliable indicator of future performance, and investors should not use historical trends to anticipate results or trends in future periods. These risks involve forward-looking statements and our actual results may differ substantially from those discussed in these forward-looking statements.

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The future trading price of our common stock could be subject to wide fluctuations in response to a variety of factors.

The future trading price of our common stock is likely to be highly volatile and could be subject to wide fluctuations in response to various factors, many of which are beyond our control, including:

• actual or anticipated results of operations and financial performance;

• general economic, industry and market conditions worldwide;

• our ability to outperform the market and outperform at a level that meets or exceeds our investors’ expectations;

• whether our guidance meets the expectations of our investors;

• the breath and liquidity of the market for our common stock;

• developments generally affecting the semiconductor industry;

• commencement of or developments relating to our involvement in litigation;

• investor perceptions of us and our business strategies;

• changes in securities analysts’ expectations or our failure to meet those expectations;

• actions by institutional or other large stockholders;

• terrorist acts or acts of war;

•  epidemics and illnesses, such as the COVID-19 outbreak first identified in China in December 2019;

• trading activity in our common stock, including short positions;

• actual or anticipated manufacturing capacity limitations;

• developments with respect to intellectual property rights;

• introduction of new products by us or our competitors;

• our sale of common stock or other securities in the future;

• conditions and trends in technology industries;

• our loss of key customers;

• changes in market valuation or earnings of our competitors;

• any mergers, acquisitions or divestitures of assets undertaken by us;

• government debt default;

• changes in corporate tax laws;

• government policies and regulations on international trade policies and restrictions, including tariffs on imports of foreign goods;

• export controls, trade and economic sanctions and regulations, and other regulatory or contractual limitations on our ability to sell or develop our products in certain foreign markets, particularly in China;

• our ability to obtain governmental licenses and approvals for international trading activities or technology transfers, including export licenses;

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• our ability to develop new products, enter new market segments, gain market share, manage litigation risk, diversify our customer base and successfully secure manufacturing capacity;

• our ability to increase our gross margins;

• our ability to accurately forecast future demand for our products;

• market reactions to guidance from other semiconductor companies or third-party research groups;

• market reactions to merger and acquisition activities in the semiconductor industry, and rumors or expectations of further consolidation in the industry;

• investments in sales and marketing resources to enter new markets;

• costs of increasing wafer capacity and qualifying additional third-party wafer fabrication facilities;

• cyber attacks or other system security, data protection and privacy breaches;

• our ability to pay quarterly cash dividends to stockholders; and

• changes in the estimation of the future size and growth rate of our markets.

In addition, the stock market often experiences substantial volatility that may be unrelated to the operating performance of particular companies. These broad market fluctuations may adversely affect the trading price of our common stock.

We expect our operating results to fluctuate from quarter to quarter and year over year, which may make it difficult to predict our future performance and could cause our stock price to decline and be volatile.

Our revenue, expenses, and results of operations are difficult to predict, have varied significantly in the past and will continue to fluctuate significantly in the future due to a number of factors, many of which are beyond our control. We expect fluctuations to continue for a number of reasons, including:

• changes in general demand for electronic products as a result of worldwide macroeconomic conditions;

• changes in business conditions at our distributors, value-added resellers and/or end-customers;

• changes in general economic conditions in the countries where our products are sold or used;

• adverse changes in laws and government regulations, such as tariffs on imports of foreign goods, export regulations and export classifications, including in foreign countries where we have offices or operations;

• the timing of developments and related expenses in our litigation matters;

• the loss of key customers or our inability to attract new customers due to customer and prospective customer concerns about being litigation targets;

• continued dependence on turns business (orders received and shipped within the same fiscal quarter);

• continued dependence on the Asian markets for our customer base;

• increases in assembly costs due to commodity price increases, such as the price of gold;

• the timing of new product introductions by us and our competitors;

• changes in our revenue mix between OEMs, ODMs, distributors and value-added resellers;

• changes in product mix, product returns, and actual and potential product liability;

• the acceptance of our new products in the marketplace;

• our ability to develop new process technologies and achieve volume production;

• our ability to meet customer product demand in a timely manner;

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• the scheduling, rescheduling, or cancellation of orders by our customers;

• the cyclical nature of demand for our customers’ products;

• fluctuations in our estimate for stock rotation reserves;

• our ability to manage our inventory levels, including the levels of inventory held by our distributors;

• our ability to accurately assess the impact of market conditions on the demand for our products;

• product obsolescence;

• seasonality and variability in the computing and storage, automotive, industrial, communications and consumer markets;

• the availability of adequate manufacturing capacity from our outside suppliers;

• increases in prices for finished wafers due to general capacity shortages;

• the potential loss of future business resulting from capacity issues;

• changes in manufacturing yields;

• movements in foreign exchange rates, interest rates or tax rates;

• the impact of new tax laws on our income tax provision and cash flows;

• the impact of tariffs on imports of foreign goods; 

• the impact of cyber attacks or other system security, data protection and privacy breaches on our business operations; and

• stock-based compensation charges primarily resulting from performance and market-based equity awards granted to our employees.

Due to the factors noted above and other risks described in this section, many of which are beyond our control, you should not rely on quarter-to-quarter or year-over-year comparisons to predict our future financial performance. Unfavorable changes in any of the above factors may seriously harm our business, financial condition and results of operations, and may cause our stock price to decline and be volatile.

Our business has been and may be significantly impacted by worldwide economic conditions, in particular changing economic conditions in China.

In recent years, global credit and financial markets experienced disruptions, and may experience disruptions in the future, including diminished liquidity and credit availability, declines in consumer confidence, declines in economic growth, increases in unemployment rates, and uncertainty about economic stability. Economic uncertainty affects businesses such as ours in a number of ways, making it difficult to accurately forecast and plan our future business activities. The tightening of credit in financial markets may lead consumers and businesses to postpone spending, which may cause our customers to cancel, decrease or delay their existing and future orders with us. In addition, financial difficulties experienced by our suppliers or distributors could result in product delays, increased accounts receivable defaults and inventory challenges. Volatility in the credit markets could severely diminish liquidity and capital availability.

Demand for our products is a function of the health of the economies in the United States, Europe, China and the rest of Asia. We cannot predict the timing, strength or duration of any economic disruption or subsequent economic recovery worldwide, in our industry, or in the different markets that we serve. We also may not accurately assess the impact of changing market and economic conditions on our business and operations. These and other economic factors have had, and may in the future have, a material adverse effect on demand for our products and on our financial condition and operating results.

In particular, since we have significant operations in China, our business development plans, results of operations and financial condition may be materially and adversely affected by significant political, social and economic developments in China. A slowdown in economic growth in China could adversely impact our customers, prospective customers, suppliers, distributors and partners in China, which could have a material adverse effect on our results of the operations and financial condition. There is no guarantee that economic downturns, whether actual or perceived, any further decrease in economic growth rates or an otherwise uncertain economic outlook in China will not occur or persist in the future, that they will not be protracted, or that governments will respond adequately to control and reverse such conditions, any of which could materially and adversely affect our business, financial condition and results of operations.

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Recent changes in international trade policy and rising concern of international tariffs, including tariffs applied to goods traded between the United States and China, could materially and adversely affect our business and results of operations.

Since the beginning of 2018, there has been increasing rhetoric, in some cases coupled with legislative or executive action, from several U.S. and foreign leaders regarding tariffs against foreign imports of certain materials. More specifically, there have been several rounds of U.S. tariffs on Chinese goods taking effect in 2018 and 2019, some of which prompted retaliatory Chinese tariffs on U.S. goods. The institution of trade tariffs both globally and between the U.S. and China specifically carries the risk of negatively affecting China’s overall economic condition, which could have a negative impact on us as we have significant operations in China. Furthermore, imposition of tariffs could cause a decrease in the sales of our products to customers located in China or other customers selling to Chinese end users, which would directly impact our business, financial condition and results of operations.

We are subject to export restrictions and laws affecting trade and investments that could materially and adversely affect our business and results of operations.

As a global company headquartered in the United States, we are subject to U.S. laws and regulations that could limit and restrict the export of some of our products and services and may restrict our transactions with certain customers, business partners and other persons, including, in certain cases, dealings with or between our employees and subsidiaries. In certain circumstances, export control and economic sanctions regulations may prohibit the export of certain products, services and technologies, and in other circumstances we may be required to obtain an export license before exporting the controlled item. Compliance with these laws and regulations has not materially limited our operations or our sales, but could materially limit them in the future, which would materially and adversely affect our business and results of operations. We maintain an export compliance program but there are risks that the compliance controls could be circumvented, exposing us to legal liabilities. We must also comply with export restrictions and laws imposed by other countries affecting trade and investments. Although these restrictions and laws have not materially restricted our operations in the recent past, there is a significant risk that they could do so in the future, which would materially and adversely affect our business and results of operations. In addition, U.S. laws and regulations and sanctions, or threat of sanctions, that could limit and restrict the export of some of our products and services to our customers may also encourage our customers to develop their own solutions to replace our products, or seek to obtain a greater supply of similar or substitute products from our competitors that are not subject to these restrictions, which could materially and adversely affect our business, financial condition and results of operations.

Moreover, U.S. government’s actions targeting exports of certain technologies to China are becoming more pervasive. For example, in May 2019, President Trump issued an executive order that invoked national emergency economic powers to implement a framework to regulate the acquisition or transfer of information communications technology in transactions that imposed undue national security risks. These actions could lead to additional restrictions on the export of products that include or enable certain technologies, including products we provide to China-based customers.

The highly cyclical nature of the semiconductor industry, which has produced significant and sometimes prolonged downturns, could materially and adversely affect our financial condition and results of operations.

Historically, the semiconductor industry has been highly cyclical and, at various times, has experienced significant downturns and wide fluctuations in supply and demand. The semiconductor industry is currently experiencing such a downturn. These conditions have caused significant variances in product demand and production capacity, as well as rapid erosion of average selling prices. The industry may experience severe or prolonged downturns in the future, which could result in downward pressure on the price of our products as well as lower demand for our products. Because significant portions of our expenses are fixed in the short term or incurred in advance of anticipated sales, we may not be able to decrease our expenses in a timely manner to offset any sales shortfall. Any significant or prolonged downturns could have a material adverse effect on our business, financial condition and results of operations.

We may not be profitable on a quarterly or annual basis.

Our profitability is dependent on many factors, including:

• our sales, which because of our turns business, are difficult to accurately forecast;

• the cancellation or rescheduling of our customers’ orders, which may occur without significant penalty to our customers;

• changes in general demand for electronic products as a result of worldwide macroeconomic conditions;

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• changes in revenue mix between OEMs, ODMs, distributors and value-added resellers;

• changes in product mix, and actual and potential product liability;

• changes in revenue mix between end market segments (i.e. computing and storage, automotive, industrial, communications and consumer);

• our competition, which could adversely impact our selling prices and our potential sales;

• our manufacturing costs, including our ability to negotiate with our vendors and our ability to efficiently run our test facility in China;

• manufacturing capacity constraints;

• level of activity in our legal proceedings, which could result in significant legal expenses;

• the impact of new tax laws and other government regulations, such as tariffs on imports of foreign goods or regulations restricting the export of goods and services between the U.S. and China;

• stock-based compensation charges primarily resulting from performance and market-based equity awards granted to our employees; and

• our operating expenses, including general and administrative expenses, selling and marketing expenses, and research and development expenses relating to products that will not be introduced and will not generate revenue until later periods, if at all.

We may not achieve profitability on a quarterly or annual basis in the future. Unfavorable changes in our operations, including any of the factors noted above, may have a material adverse effect on our quarterly or annual profitability.

We may not experience growth rates comparable to past years.

In the past, our revenue increased significantly in certain years due to increased sales of certain of our products. We are subject to numerous risks and factors that could cause a decrease in our growth rates compared to past periods, including increased competition, loss of certain of our customers, unfavorable changes in our operations, reduced global electronics demand, a deterioration in market conditions, end-customer market downturn, market acceptance and penetration of our current and future products, and litigation. A material decrease in our growth rates could adversely affect our stock price and results of operations.  

We may be unsuccessful in developing and selling new products with margins similar to or better than what we have experienced in the past, which would impact our overall gross margin and financial performance.

Our success depends on products that are differentiated in the market, which result in gross margins that have historically been above industry averages. Should we fail to improve our gross margin in the future, and accordingly develop and introduce sufficiently differentiated products that result in higher gross margins than industry averages, our business, financial condition and results of operations could be materially and adversely affected.    

Industry consolidation may lead to increased competition and may harm our operating results.

In recent years, there has been a trend toward semiconductor industry consolidation. We expect this trend to continue as companies attempt to improve the leverage of growing research and development costs, strengthen or hold their market positions in an evolving industry, or become unable to continue operations unless they find an acquirer or consolidate with another company. In addition, companies that are strategic alliance partners in some areas of our business may acquire or form alliances with our competitors, thereby reducing their business with us. We believe that semiconductor industry consolidation may result in stronger competitors that are better able to compete as sole-source vendors for customers. This could lead to more variability in our operating results and could have a material adverse effect on our business, financial condition and results of operations.

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If demand for our products declines in the major end markets that we serve, our revenue will decrease and our results of operations and financial condition would be materially and adversely affected.

We believe that the application of our products in the computing and storage, automotive, industrial, communications and consumer markets will continue to account for the majority of our revenue. If the demand for our products declines in the major end markets that we serve, our revenue will decrease and our results of operations and financial condition would be materially and adversely affected. In addition, as technology evolves, the ability to integrate the functionalities of various components, including our discrete semiconductor products, onto a single chip and/or onto other components of systems containing our products increases. Should our customers require integrated solutions that we do not offer, demand for our products could decrease, and our business, financial condition and results of operations would be materially and adversely affected.

We may be unsuccessful in developing and selling new products or in penetrating new markets required to maintain or expand our business.

Our competitiveness and future success depend on our ability to design, develop, manufacture, assemble, test, market, and support new products and enhancements on a timely and cost-effective basis. A fundamental shift in technologies in any of our product markets could have a material adverse effect on our competitive position within these markets. Our failure to timely develop new technologies or to react quickly to changes in existing technologies could materially delay our development of new products, which could result in product obsolescence, decreased revenue, and/or a loss of market share to competitors.

As we develop new product lines, we must adapt to market conditions that are unfamiliar to us, such as competitors and distribution channels that are different from those we have known in the past. Some of our new product lines require us to re-equip our labs to test parameters we have not tested in the past. If we are unable to adapt rapidly to these new and additional conditions, we may not be able to successfully penetrate new markets.

The success of a new product depends on accurate forecasts of long-term market demand and future technological developments, as well as on a variety of specific implementation factors, including:

• timely and efficient completion of process design and device structure improvements;

• timely and efficient implementation of manufacturing, assembly, and test processes;

• the ability to secure and effectively utilize fabrication capacity in different geometries;

• product performance;

• product availability;

• product quality and reliability; and

• effective marketing, sales and service. 

To the extent that we fail to timely introduce new products or to quickly penetrate new markets, our business, financial condition and results of operations could be materially and adversely affected.

We may face competition from customers developing products internally.

Our customers generally have substantial technological capabilities and financial resources. Some customers have traditionally used these resources to develop their own products internally. The future prospects for our products in these markets are dependent in part upon our customers' acceptance of our products as an alternative to their internally developed products. Future sales prospects also are dependent upon acceptance of third-party sourcing for products as an alternative to in-house development. Customers may in the future continue to use internally developed components. They may also decide to develop or acquire components, technologies or products that are similar to, or that may be substituted for, our products. If our customers fail to accept our products as an alternative, if they develop or acquire the technology to develop such components internally rather than purchase our products, or if we are otherwise unable to develop or maintain strong relationships with them, our business, financial condition and results of operations could be materially and adversely affected.

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We derive most of our revenue from direct or indirect sales to customers in Asia and have significant operations in Asia, which may expose us to political, cultural, regulatory, economic, foreign exchange, and operational risks.

We derive most of our revenue from customers located in Asia through direct sales or indirect sales through distribution arrangements and value-added reseller agreements with parties located in Asia. As a result, we are subject to increased risks due to this geographic concentration of business and operations. For the year ended December 31, 2019, 89% of our revenue was from customers in Asia. There are risks inherent in doing business in Asia, and internationally in general, including:

• changes in, or impositions of, legislative or regulatory requirements, including tax laws in the U.S. and in the countries in which we manufacture or sell our products, and government action to restrict our ability to sell to foreign customers where sales of products may require export license;

• trade restrictions, including restrictions imposed by the United States on trading with parties in foreign countries;

• currency exchange rate fluctuations impacting intra-company transactions;

• the fluctuations in the value of the U.S. Dollar relative to other foreign currencies, which could affect the competitiveness of our products;

• transportation delays;

• changes in tax regulations in China that may impact our tax status in Chengdu, Hangzhou and other regions where we have significant operations;

• tariffs imposed by China and the United States that may impact our sales;

• export controls, trade and economic sanctions and regulations, and other regulatory or contractual limitations on our ability to sell or develop our products in China;

• multi-tiered distribution channels that lack visibility to end customer pricing and purchase patterns;

• international political relationships and threats of war;

• terrorism and threats of terrorism;

• epidemics and illnesses, such as the COVID-19 outbreak first identified in China in December 2019;

• work stoppages and infrastructure problems due to adverse weather conditions or natural disasters;

• work stoppages related to employee dissatisfaction;

• economic, social and political instability;

• longer accounts receivable collection cycles and difficulties in collecting accounts receivables;

• enforcing contracts generally; and

• less effective protection of intellectual property and contractual arrangements.

If we fail to expand our customer base and significantly reduce the geographic concentration of our customers, we will continue to be subject to the foregoing risks, which could materially and adversely affect our business, financial condition and results of operations.

We depend on a limited number of customers, including distributors, for a significant percentage of our revenue.

Historically, we have generated most of our revenue from a limited number of customers, including distributors. For example, sales to our largest distributor accounted for 23% of our total revenue for the year ended December 31, 2019. We continue to rely on a limited number of customers for a significant portion of our revenue. Because we rely on a limited number of customers for significant percentages of our revenue, a decrease in demand or significant pricing pressure for our products from any of our major customers for any reason (including due to competition, market conditions, catastrophic events or otherwise) could have a materially adverse impact on our business, financial condition and results of operations.

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We are subject to anti-corruption laws in the jurisdictions in which we operate, including the U.S. Foreign Corrupt Practices Act (the “FCPA”). Our failure to comply with these laws could result in penalties which could harm our reputation and have a material adverse effect on our business, financial condition and results of operations.

We are subject to the FCPA, which generally prohibits companies and their intermediaries from making improper payments to foreign officials for the purpose of obtaining or keeping business and/or other benefits, along with various other anti-corruption laws. Although we have implemented policies and procedures designed to ensure that we, our employees and other intermediaries comply with the FCPA and other anti-corruption laws to which we are subject, there is no assurance that such policies or procedures will work effectively all of the time or protect us against liability under the FCPA or other laws for actions taken by our employees and other intermediaries with respect to our business or any businesses that we may acquire. We have significant operations in Asia, which place us in frequent contact with persons who may be considered “foreign officials” under the FCPA, resulting in an elevated risk of potential FCPA violations. If we are not in compliance with the FCPA and other laws governing the conduct of business with government entities (including local laws), we may be subject to criminal and civil penalties and other remedial measures, which could have a material adverse impact on our business, financial condition, results of operations and liquidity. Any investigation of any potential violations of the FCPA or other anti-corruption laws by the U.S. or foreign authorities could harm our reputation and have an adverse impact on our business, financial condition and results of operations.

We receive a significant portion of our revenue from distribution arrangements, value-added resellers and direct customers, and the loss of any one of these distributors, value-added resellers or direct customers or failure to collect a receivable from them could adversely affect our financial position and results of operations.

We market our products through distribution arrangements and value-added resellers and through our direct sales and applications support organization to customers that include OEMs, ODMs and EMS providers. Receivables from our customers are generally not secured by any type of collateral and are subject to the risk of being uncollectible. Sales to our largest distributor accounted for 23% of our total revenue for the year ended December 31, 2019. Significant deterioration in the liquidity or financial condition of any of our major customers or any group of our customers could have a material adverse impact on the collectability of our accounts receivable and our future operating results. We primarily conduct our sales on a purchase order basis, and we do not have any long-term supply commitments. 

Moreover, we believe a high percentage of our products are eventually sold to a number of OEMs. Although we communicate with OEMs in an attempt to achieve “design wins,” which are decisions by OEMs and/or ODMs to incorporate our products, we do not have purchase commitments from these end users. Therefore, there can be no assurance that the OEMs and/or ODMs will continue to incorporate our ICs into their products. OEM technical specifications and requirements can change rapidly, and we may not have products that fit new specifications from an end customer for whom we have had previous design wins. We cannot be certain that we will continue to achieve design wins from large OEMs, that our direct customers will continue to be successful in selling to the OEMs, or that the OEMs will be successful in selling products which incorporate our ICs. The loss of any significant customer, any material reduction in orders by any of our significant customers or by their OEM customers, the cancellation of a significant customer order, or the cancellation or delay of a customer’s or an OEM’s significant program or product could reduce our revenue and adversely affect our financial condition and results of operations. 

Due to the nature of our business as a component supplier, we may have difficulty both in accurately predicting our future revenue and appropriately managing our expenses.

Because we provide components for end products and systems, demand for our products is influenced by our customers’ end product demand. As a result, we may have difficulty in accurately forecasting our revenue and expenses. Our revenue depends on the timing, size, and speed of commercial introductions of end products and systems that incorporate our products, all of which are inherently difficult to forecast, as well as the ongoing demand for previously introduced end products and systems. In addition, demand for our products is influenced by our customers’ ability to manage their inventory. Our sales to distributors are subject to higher volatility because they service demand from multiple levels of the supply chain which, in itself, is inherently difficult to forecast. If our customers, including distributors, do not manage their inventory correctly or misjudge their customers’ demand, our shipments to and orders from our customers may vary significantly on a quarterly basis, which could reduce our revenue and adversely affect our financial condition and results of operations. 

Our ability to increase product sales and revenue may be constrained by the manufacturing capacity of our suppliers.

Although we provide our suppliers with rolling forecasts of our production requirements, their ability to provide wafers to us is limited by the available capacity, particularly capacity in the geometries we require, at the facilities in which they manufacture wafers for us.  As a result, this lack of capacity has at times constrained our product sales and revenue growth. In addition, an increased need for capacity to meet internal demands or demands of other customers could cause our suppliers to reduce capacity available to us. Our suppliers may also require us to pay amounts in excess of contracted or anticipated amounts for wafer deliveries or require us to make other concessions in order to acquire the wafer supply necessary to meet our customer requirements. If our suppliers extend lead times, limit supplies or the types of capacity we require, or increase prices due to capacity constraints or other factors, our revenue and gross margin may materially decline. In addition, if we experience supply delays or limitations, our customers may reduce their purchase levels with us and/or seek alternative solutions to meet their demand, which could materially and adversely impact our business and results of operations. Delays in increasing third-party manufacturing capacity may also limit our ability to meet customer demand.

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We currently depend on third-party suppliers to provide us with wafers for our products. If any of our wafer suppliers become insolvent or capacity constrained and are unable to provide us sufficient wafers at acceptable yields and at anticipated costs, our revenue and gross margin may decline or we may not be able to fulfill our customer orders.

We have a supply arrangement with certain suppliers for the production of wafers. Should any of our suppliers become insolvent or capacity constrained, we may not be able to fulfill our customer orders, which would likely cause a decline in our revenue.

While certain aspects of our relationship with these suppliers are contractual, many important aspects of this relationship depend on our suppliers’ continued cooperation and our management of the supplier relationships. In addition, the fabrication of ICs is a highly complex and precise process. Problems in the fabrication process can cause a substantial percentage of wafers to be rejected or numerous ICs on each wafer to be non-functional. This could potentially reduce yields. The failure of our suppliers to supply us wafers at acceptable yields could prevent us from fulfilling our customer orders for our products and would likely cause a decline in our revenue.  

Further, as is common in the semiconductor industry, our customers may reschedule or cancel orders on relatively short notice. If our customers cancel orders after we submit a committed forecast to our suppliers for the corresponding wafers, we may be required to purchase wafers that we may not be able to resell, which would adversely affect our financial condition, results of operations and cash flows.

We might not be able to deliver our products on a timely basis if our relationships with our assembly and test subcontractors are disrupted or terminated.

We do not have direct control over product delivery schedules or product quality because all of our products are assembled by third-party subcontractors and a portion of our testing is currently performed by third-party subcontractors. Also, due to the amount of time typically required to qualify assembly and test subcontractors, we could experience delays in the shipment of our products if we were forced to find alternate third parties to assemble or test our products. In addition, events such as global economic crises may materially impact our assembly suppliers’ ability to operate. Any future product delivery delays or disruptions in our relationships with our subcontractors could have a material adverse effect on our financial condition, results of operations and cash flows. 

There may be unanticipated costs associated with adding to or supplementing our third-party suppliers’ manufacturing capacity.

We anticipate that future growth of our business will require increased manufacturing capacity on the part of third-party supply foundries, assembly shops, and testing facilities for our products. In order to facilitate such growth, we may need to enter into strategic transactions, investments and other activities. Such activities are subject to a number of risks, including:

• the costs and expense associated with such activities;

• the availability of modern foundries to be developed, acquired, leased or otherwise made available to us or our third-party suppliers;

• the ability of foundries and our third-party suppliers to obtain the advanced equipment used in the production of our products;

• delays in bringing new foundry operations online to meet increased product demand; and

• unforeseen environmental, engineering or manufacturing qualification problems relating to existing or new foundry facilities, including delays in qualification of new foundries by our customers.

These and other risks may affect the ultimate cost and timing of any expansion of our third-party suppliers’ capacity.

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We purchase inventory in advance based on expected demand for our products, and if demand is not as expected, we may have insufficient or excess inventory, which could adversely impact our financial position.

As a fabless semiconductor company, we purchase our inventory from third-party manufacturers in advance of selling our products. We place orders with our manufacturers based on existing and expected orders from our customers for particular products. While most of our contracts with our customers and distributors include lead time requirements and cancellation penalties that are designed to protect us from misalignment between customer orders and inventory levels, we must nonetheless make some predictions when we place orders with our manufacturers. In the event that our predictions are inaccurate due to unexpected increases in orders or unavailability of product within the timeframe that is required, we may have insufficient inventory to meet our customer demands. In addition, a perceived negative trend in market condition could lead us to decrease the manufacturing volume of our products to avoid excess inventory.  If we inaccurately assessed the market conditions for our products, we would have insufficient inventory to meet our customer demands. In the event that we order products that we are unable to sell due to a decrease in orders, unexpected order cancellations, injunctions due to patent litigation, or product returns, we may have excess inventory which, if not sold, may need to be written down or would result in a decrease in our revenue in future periods as the excess inventory at our distributors is sold. If any of these situations were to arise, it could have a material impact on our business, financial condition and results of operations.

The complexity of calculating our tax provision may result in errors that could result in restatements of our financial statements.

Due to the complexity associated with the calculation of our tax provision, including the effects of the 2017 Tax Act and the enactment of other tax laws, we engage third-party tax advisors to assist us in the calculation. If we or our tax advisors fail to resolve or fully understand certain issues that we may have had in the past and issues that may arise in the future, we could be subject to errors, which, if material, would result in us having to restate our financial statements. Restatements are generally costly and could adversely impact our results of operations, damage our reputation, and/or have a negative impact on the trading price of our common stock.  

Changes in effective tax rates or adverse outcomes resulting from examination of our income tax returns could adversely affect our results of operations.

Our future effective tax rates could be adversely affected by earnings being lower than anticipated in countries where we have lower statutory rates and higher than anticipated in countries where we have higher statutory rates, by changes in the valuation of our deferred tax assets, or by changes in tax laws such as the 2017 Tax Act, regulations, accounting principles or interpretations thereof and discrete items such as vesting of restricted stock units (“RSUs”). In addition, we are subject to potential future examinations of our income tax returns by the Internal Revenue Service (“IRS”) and other tax authorities. We assess the likelihood of adverse outcomes resulting from these examinations to determine the adequacy of our provision for income taxes. There can be no assurance that the outcomes from any examinations will not have an adverse effect on our financial condition and results of operations.

Our international operations subject us to potentially significant tax consequences, which could adversely affect our results of operations.

We conduct our international operations through wholly-owned subsidiaries, branches and representative offices and report our taxable income in various jurisdictions worldwide based upon our business operations in those jurisdictions. Such corporate structures are subject to complex transfer pricing regulations administered by taxing authorities in various jurisdictions. The relevant taxing authorities may disagree with our determinations as to the income and expenses attributable to specific jurisdictions. If such a disagreement were to occur, and our positions were not sustained, we could be required to pay additional taxes, interest and penalties, resulting in higher effective tax rates, reduced cash flows and lower overall profitability of our operations. Additionally, our future worldwide tax rate and financial position may be affected by changes in the relevant tax laws, interpretation of such tax laws or the influence of certain tax policy efforts of the European Union and the Organization for Economic Co-operation and Development ("OECD").

Implementation of an enterprise resource planning (“ERP”) or other information technology systems could result in significant disruptions to our operations.

From time to time, we may implement new ERP software solutions or upgrade existing systems. Implementation of these solutions and systems is highly dependent on coordination of system providers and internal business teams. We may experience difficulties as we transition to these new or upgraded systems and processes, including loss or corruption of financial, business or customer data. In addition, transitioning to these new systems requires significant capital investments and personnel resources. Difficulties in implementing new or upgraded information systems or any significant system failures could disrupt our operations, which could have a material adverse effect on our capital resources, financial condition or results of operations.

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System security risks, data protection or privacy breaches, cyber attacks and systems integration issues could disrupt our internal operations and/or harm our reputation, and any such disruption or harm could cause a reduction in our expected revenue, increase our expenses, negatively impact our results of operation or otherwise adversely affect our stock price.

Experienced computer programmers and hackers may be able to penetrate our network security and misappropriate or compromise our confidential and proprietary information, create system disruptions or cause shutdowns. The costs to us to eliminate or alleviate cyber or other security problems, bugs, viruses, worms, malicious software programs and security vulnerabilities could be significant, and our efforts to address these problems may not be successful and could result in interruptions and delays that may impede our sales, manufacturing, distribution, financial reporting or other critical functions.

In the ordinary course of business, we store sensitive data on our internal systems, network and servers, such as proprietary business and financial information, and confidential data pertaining to our customers, suppliers and business partners. The secure maintenance of sensitive information on our networks and the protection features of our solutions are both critical to our operations and business strategy. We devote significant resources to network security, data encryption, and other security measures to protect our systems and data. However, these security measures cannot provide absolute security.  Although we make significant efforts to maintain the security and integrity of our systems and solutions, any destructive or intrusive breach could compromise our networks, creating system disruptions or slowdowns, and the information stored on our networks could be accessed, publicly disclosed, lost or stolen. If any of these types of security breaches were to occur and we were unable to protect sensitive data, our relationships with our business partners and customers could be materially damaged, our reputation could be materially harmed, and we could be exposed to a risk of litigation and possible significant liability.

Portions of our IT infrastructure also may experience interruptions, delays or cessations of service or produce errors in connection with systems integration or migration work that takes place from time to time. We may not be successful in implementing new systems and transitioning data, which could cause business disruptions and our remediation efforts may be expensive, time consuming, disruptive and resource-intensive. Such disruptions could adversely impact our ability to fulfill orders and interrupt other processes. Delayed sales or lost customers resulting from these disruptions could adversely affect our financial results, stock price and reputation.

Effective May 25, 2018, the European Union (“EU”) implemented the General Data Protection Regulation (“GDPR”), a broad data protection framework that expands the scope of current EU data protection law to non-European Union entities that process, or control the processing of, the personal information of EU subjects. The GDPR allows for the imposition of fines and corrective action on entities that improperly use or disclose the personal information of EU subjects, including through a data security breach. The State of California enacted the California Consumer Privacy Act of 2018 (“CCPA”), effective on January 1, 2020, which contains requirements similar to GDPR for the handling of personal information of California residents, commencing on January 1, 2020.

Our failure to fully comply with GDPR, CCPA and other laws could lead to significant fines and require onerous corrective action. In addition, data security breaches experienced by us could result in the loss of trade secrets or other intellectual property, public disclosure of sensitive commercial data, and the exposure of personally identifiable information (including sensitive personal information) of our employees, customers, suppliers and others.

Unauthorized use or disclosure of, or access to, any personal information maintained by us or on our behalf, whether through breach of our systems, breach of the systems of our suppliers or vendors by an unauthorized party, or through employee error, theft or misuse, or otherwise, could harm our business. If any such unauthorized use or disclosure of, or access to, such personal information was to occur, our operations could be seriously disrupted, and we could be subject to demands, claims and litigation by private parties, and investigations, related actions, and penalties by regulatory authorities. In addition, we could incur significant costs in notifying affected persons and entities and otherwise complying with the multitude of foreign, federal, state and local laws and regulations relating to the unauthorized access to, or use or disclosure of, personal information. Finally, any perceived or actual unauthorized access to, or use or disclosure of, such information could harm our reputation, substantially impair our ability to attract and retain customers and have an adverse impact on our business, financial condition and results of operations.

If we are unsuccessful in legal proceedings brought against us or any of our customers, we could be prevented from selling many of our products or be required to pay substantial damages. An unfavorable outcome or an additional award of damages, attorneys’ fees or an injunction could cause our revenue to decline significantly and could severely harm our business and operating results.

From time to time we are a party to various legal proceedings. If we are not successful in litigation that could be brought against us or our customers, we could be ordered to pay monetary fines and/or damages. If we are found liable for willful patent infringement, damages could be significant. We and/or our customers could also be prevented from selling some or all of our products. Moreover, our customers and end users could decide not to use our products, and our products and our customers’ accounts payable to us could be seized. Finally, interim developments in these proceedings could increase the volatility in our stock price as the market assesses the impact of such developments on the likelihood that we will or will not ultimately prevail in these proceedings.

Given our inability to control the timing and nature of significant events in our legal proceedings that either have arisen or may arise, our legal expenses are difficult to forecast and may vary substantially from our publicly disclosed forecasts with respect to any given quarter, which could contribute to increased volatility in our stock price and financial condition.

Historically, we have incurred significant expenses in connection with various legal proceedings that vary with the level of activity in the proceeding. It is difficult for us to forecast our legal expenses for any given quarter, which adversely affects our ability to forecast our expected results of operations in general. We may also be subject to unanticipated legal proceedings, which would result in us incurring unexpected legal expenses. If we fail to meet the expectations of securities or industry analysts as a result of unexpected changes in our legal expenses, our stock price could be materially impacted.

Future legal proceedings may divert our financial and management resources.

The semiconductor industry is characterized by frequent claims of infringement and litigation regarding patent and other intellectual property rights. Patent infringement is an ongoing risk, in part because other companies in our industry could have patent rights that may not be identifiable when we initiate development efforts. Litigation may be necessary to enforce our intellectual property rights, and we may have to defend ourselves against additional infringement claims. Such litigation is very costly. In the event any third party makes a new infringement claim against us or our customers, we could incur additional ongoing legal expenses. In addition, in connection with these legal proceedings, we may be required to post bonds to defend our intellectual property rights in certain countries for an indefinite period of time, until such dispute is resolved. If our legal expenses materially increase or exceed anticipated amounts, our capital resources and financial condition could be adversely affected. Further, if we are not successful in any of our intellectual property defenses, our financial condition could be adversely affected and our business could be harmed. Our management team may also be required to devote a great deal of time and effort to these legal proceedings, which could divert management’s attention from focusing on our operations and adversely affect our business.

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Failure to protect our proprietary technologies or maintain the right to certain technologies may negatively affect our ability to compete.

We rely heavily on our proprietary technologies. Our future success and competitive position depend in part upon our ability to obtain and maintain protection of certain proprietary technologies used in our products. We pursue patents for some of our new products and unique technologies, and we also rely on a combination of nondisclosure agreements and other contractual provisions, as well as our employees’ commitment to confidentiality and loyalty, to protect our technology, know-how and processes. Despite the precautions we take, it may be possible for unauthorized third parties to copy aspects of our current or future technologies or products, or to obtain and use information that we regard as proprietary. We intend to continue to protect our proprietary technologies, including through patents. However, there can be no assurance that the steps we take will be adequate to protect our proprietary rights, that our patent applications will lead to issued patents, that others will not develop or patent similar or superior products or technologies, or that our patents will not be challenged, invalidated or circumvented by others. Furthermore, the laws of the countries in which our products are or may be developed, manufactured or sold may not protect our products and intellectual property rights to the same extent as laws in the United States. Our failure to adequately protect our proprietary technologies could materially harm our business. 

We face risks in connection with our internal control over financial reporting.

Effective internal control over financial reporting is necessary for us to provide reliable and accurate financial reports. If we cannot provide reliable financial reports or prevent fraud or other financial misconduct, our business and operating results could be harmed. Our failure to implement and maintain effective internal control over financial reporting could result in a material misstatement of our financial statements or otherwise cause us to fail to meet our financial reporting obligations. This, in turn, could result in a loss of investor confidence in the accuracy and completeness of our financial reports, which could have an adverse effect on our results of operations and/or have a negative impact on the trading price of our common stock, and could subject us to stockholder litigation. In addition, we cannot assure you that we will not in the future identify material weaknesses in our internal control over financial reporting that we have not discovered to date, which may impact the reliability of our financial reporting and financial statements. 

Our products must meet specifications, and undetected defects and failures may occur, which may cause customers to return or stop buying our products and may expose us to product liability risk.

Our customers generally establish demanding specifications for quality, performance, and reliability that our products must meet. ICs as complex as ours often encounter development delays and may contain undetected defects or failures when first introduced or after commencement of commercial shipments, which might require product replacement or recall. Further, our third-party manufacturing processes or changes thereof, or raw material used in the manufacturing processes may cause our products to fail. We have from time to time in the past experienced product quality, performance or reliability problems. Our standard warranty period is generally one to two years, which exposes us to significant risks of claims for defects and failures. If defects and failures occur in our products, we could experience lost revenue, increased costs, including warranty expense and costs associated with customer support, cancellations or rescheduling of orders or shipments, and product returns or discounts, any of which would harm our operating results.

In addition, product liability claims may be asserted with respect to our technology or products. Although we currently have insurance, there can be no assurance that we have obtained a sufficient amount of insurance coverage, that asserted claims will be within the scope of coverage of the insurance, or that we will have sufficient resources to satisfy any asserted claims.

The price and availability of commodities (e.g., gold, copper and silicon) may adversely impact our ability to deliver our products in a timely and cost-effective manner, and may adversely affect our business and results of operations.

Our products incorporate commodities such as gold, copper and silicon. An increase in the price or a decrease in the availability of these commodities and similar commodities that we use could negatively impact our business and results of operations.

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Fluctuations in the value of the U.S. Dollar relative to other foreign currencies, including the Renminbi, may adversely affect results of operations.

Our manufacturing and packaging suppliers are and will continue to be primarily located in China for the foreseeable future. If the value of the Renminbi rises against the U.S. Dollar, there could be an increase in our manufacturing costs relative to competitors who have manufacturing facilities located in the U.S., which could adversely affect our operations. In addition, our sales are primarily denominated in the U.S. Dollar. If the value of the U.S Dollar rises against other currencies, it may adversely affect the demand for our products in international markets, which could negatively impact our business and results of operations.

We incur foreign currency exchange gains or losses related to the timing of payments for transactions between the U.S. and our foreign subsidiaries, which are reported in interest and other income in the statements of operations. Fluctuations in the value of the U.S. Dollar relative to the foreign currencies could increase the amount of foreign currency exchange losses we record, which could have an adverse impact on our results of operations.

Our business is subject to various governmental laws and regulations, and compliance with these regulations may impact our revenue and cause us to incur significant expense. If we fail to maintain compliance with applicable regulations or obtain government licenses and approvals for our desired international trading activities or technology transfers, we may be forced to recall products and cease their distribution, and we could be subject to civil or criminal penalties.

Our business is subject to various significant laws and other legal requirements imposed by the U.S. and other countries we conduct business with, including export control laws such as the Export Administration Act, the Export Administration Regulations (“EAR”) and other laws, regulations and requirements governing international trade and technology transfer. These laws and regulations are complex, change frequently and have generally become more stringent over time. We may be required to incur significant expense to comply with these regulations or to remedy violations of these regulations. In addition, if our customers fail to comply with these regulations, we may be required to suspend sales to these customers, which could negatively impact our results of operations. We must conform the manufacture and distribution of our products to various laws and adapt to regulatory requirements in many countries as these requirements change. If we fail to comply with these requirements in the manufacture or distribution of our products, we could be required to pay civil penalties, face criminal prosecution and, in some cases, be prohibited from distributing our products commercially until the products are brought into compliance.

Environmental laws and regulations could cause a disruption in our business and operations.

We are subject to various state, federal and international laws and regulations governing the environment, including those restricting the presence of certain substances in electronic products and making manufacturers of those products financially responsible for the collection, treatment, recycling and disposal of certain products. Such laws and regulations have been passed in several jurisdictions in which we operate, including various European Union member countries and countries in Asia. There can be no assurance that similar laws and regulations will not be implemented in other jurisdictions resulting in additional costs, possible delays in delivering products, and even the discontinuance of existing and planned future products if the cost were to become prohibitive.

We and our manufacturing partners are or will be subject to extensive Chinese government regulation, and the benefit of various incentives from Chinese governments that we and our manufacturing partners receive may be reduced or eliminated, which could increase our costs or limit our ability to sell products and conduct activities in China.

We have manufacturing and testing facilities in China and most of our manufacturing partners are located in China. The Chinese government has broad discretion and authority to regulate the technology industry in China. Additionally, China’s government has implemented policies from time to time to regulate economic expansion in China. It exercises significant control over China’s economic growth through the allocation of resources, controlling payment of foreign currency-denominated obligations, setting monetary policy and providing preferential treatment to particular industries or companies.

Personal privacy, cyber security, and data protection are becoming increasingly significant issues in China. To address these issues, the Standing Committee of the National People’s Congress promulgated the Cyber Security Law of the People’s Republic of China (the “Cyber Security Law”), which took effect on June 1, 2017. The Cyber Security Law sets forth various requirements relating to the collection, use, storage, disclosure and security of data, among other things. Various Chinese agencies are expected to issue additional regulations in the future to define these requirements more precisely. These requirements may increase our costs of compliance. We cannot assure you that we will be able to comply with all of these regulatory requirements. Any failure to comply with the Cyber Security Law and the relevant regulations and policies could result in further cost and liability to us and could adversely affect our business and results of operations. Additionally, increased costs to comply with, and other burdens imposed by, the Cyber Security Law and relevant regulations and policies that are applicable to the businesses of our suppliers, vendors and other service providers, as well as our customers, could adversely affect our business and results of operations.

Any additional new regulations or the amendment or modification of previously implemented regulations could require us and our manufacturing partners to change our business plans, increase our costs, or limit our ability to sell products and conduct activities in China, which could adversely affect our business and operating results.

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The Chinese government and provincial and local governments also have provided, and continue to provide, various incentives to encourage the development of the semiconductor industry in China. Such incentives include tax rebates, reduced tax rates, favorable lending policies and other measures, some or all of which may be available to our manufacturing partners and to us with respect to our facilities in China. Any of these incentives could be reduced or eliminated by governmental authorities at any time. Any such reduction or elimination of incentives currently provided to us and our manufacturing partners could adversely affect our business and operating results. 

There are inherent risks associated with the operation of our manufacturing and testing facilities in China, which could increase product costs or cause a delay in product shipments.

We have manufacturing and testing facilities in China. We face the following risks, among others, with respect to our operations in China:

• inability to hire and maintain a qualified workforce;

• inability to maintain appropriate and acceptable manufacturing controls; and

• higher than anticipated overhead and other costs of operation.

If we are unable to maintain our facilities in China at fully operational status with qualified workers, appropriate manufacturing controls and reasonable cost levels, we may incur higher costs than our current expense levels, which would affect our gross margins. In addition, if capacity restraints result in significant delays in product shipments, our business and results of operations would be adversely affected.

The average selling prices of products in our markets have historically decreased over time and could do so in the future, which could harm our revenue and gross profits.

Average selling prices of semiconductor products in the markets we serve have historically decreased over time. Our gross profits and financial results will suffer if we are unable to offset any reductions in our average selling prices by reducing our costs, developing new or enhanced products on a timely basis with higher selling prices or gross profits, or increasing our sales volumes. Additionally, because we do not operate our own wafer manufacturing or assembly facilities, we may not be able to reduce our costs as rapidly as companies that operate their own facilities, and our costs may even increase, which could also reduce our profit margins.

Because of the lengthy sales cycles for our products and the fixed nature of a significant portion of our expenses, we may incur substantial expenses before we earn associated revenue and may not ultimately achieve our forecasted sales for our products.

The introduction of new products presents significant business challenges because product development plans and expenditures may be made up to two years or more in advance of any sales. It generally takes us up to 12 months or more to design and manufacture a new product prototype. Only after we have a prototype do we introduce the product to the market and begin selling efforts in an attempt to achieve design wins. This sales process requires us to expend significant sales and marketing resources without any assurance of success. Volume production of products that use our ICs, if any, may not be achieved for an additional period of time after an initial sale. Sales cycles for our products are lengthy for a number of reasons, including:

• our customers usually complete an in-depth technical evaluation of our products before they place a purchase order;

• the commercial adoption of our products by OEMs and ODMs is typically limited during the initial release of their product to evaluate product performance and consumer demand;

• our products must be designed into our customers’ products or systems; and

• the development and commercial introduction of our customers’ products incorporating new technologies are frequently delayed.

As a result of our lengthy sales cycles, we may incur substantial expenses before we earn associated revenue because a significant portion of our operating expenses is relatively fixed and based on expected revenue. The lengthy sales cycles of our products also make forecasting the volume and timing of orders difficult. In addition, the delays inherent in lengthy sales cycles raise additional risks that customers may cancel or change their orders. Our sales are made by purchase orders. Because industry practice allows customers to reschedule or cancel orders on relatively short notice, backlog is not always a good indicator of our future sales. If customer cancellations or product changes occur, we could lose anticipated sales and not have sufficient time to reduce our inventory and operating expenses.   

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Our success depends on our investment of significant resources in research and development. We may have to invest more resources in research and development than anticipated, which could increase our operating expenses and negatively impact our operating results.

Our success depends on us investing significant amounts of resources into research and development. We expect to have to continue to invest heavily in research and development in the future in order to continue to innovate and introduce new products in a timely manner and increase our revenue and profitability. If we have to invest more resources in research and development than we anticipate, we could see an increase in our operating expenses which may negatively impact our operating results. Also, if we are unable to properly manage and effectively utilize our research and development resources, we could see material adverse effects on our business, financial condition and operating results.

In addition, if new competitors, technological advances by existing competitors, our entry into new markets, or other competitive factors require us to invest significantly greater resources than anticipated in our research and development efforts, our operating expenses would increase. If we are required to invest significantly greater resources than anticipated in research and development efforts without a corresponding increase in revenue, our operating results could decline. Research and development expenses are likely to fluctuate from time to time to the extent we make periodic incremental investments in research and development and these investments may be independent of our level of revenue, which could negatively impact our financial results. In order to remain competitive, we anticipate that we will continue to devote substantial resources to research and development, and we expect these expenses to increase in absolute dollars in the foreseeable future due to the increased complexity and the greater number of products under development.

The loss of any of our key personnel or the failure to attract or retain specialized technical and management personnel could affect our operations or impair our ability to grow our business.

Our future success depends upon our ability to attract and retain highly qualified technical and managerial personnel. We are particularly dependent on the continued services of our key executives, including Michael Hsing, our President and Chief Executive Officer, who founded our company and developed our proprietary process technology. In addition, personnel with highly skilled analog and mixed-signal design engineering expertise are scarce and competition for personnel with these skills is intense. There can be no assurance that we will be able to retain existing key employees or that we will be successful in attracting, integrating or retaining other highly qualified personnel with critical capabilities in the future. If we are unable to retain the services of existing key employees or are unsuccessful in attracting new highly qualified employees quickly enough to meet the demands of our business, including design cycles, our business could be harmed. Furthermore, if we lose key personnel, the search for a qualified replacement and the transition could interrupt our operations as the search could take us longer than expected and divert management resources, and the newly hired employee could take longer than expected to integrate into the team.

If we fail to retain key employees in our sales, applications, finance and legal staff or to make continued improvements to our internal systems, particularly in the accounting and finance area, our business may suffer.

If we fail to continue to adequately staff our sales, applications, financial and legal staff, maintain or upgrade our business systems and maintain internal control that meet the demands of our business, our ability to operate effectively will suffer. The operation of our business also depends upon our ability to retain these employees, as these employees hold a significant amount of institutional knowledge about us and our products, and, if they were to terminate their employment, our sales and internal control over financial reporting could be adversely affected.

We intend to continue to expand our operations, which may strain our resources and increase our operating expenses.

We plan to continue to expand our domestic and foreign operations through internal growth, strategic relationships, and/or acquisitions. We expect that any such expansion will strain our systems and operational and financial controls. In addition, we are likely to incur significantly higher operating costs. To manage our growth effectively, we must continue to improve and expand our systems and controls, as well as hire experienced administrative and financial personnel. If we fail to do so, our growth will be limited. If we fail to effectively manage our planned expansion of operations, our business and operating results may be harmed.

We may not realize the anticipated benefits of any company or business that we acquire. In addition, acquisitions could result in diluting the ownership interests of our stockholders, reduce our cash balances, and cause us to incur debt or to assume contingent liabilities, which could adversely affect our business. We may also be the target of strategic transactions, which could divert our management’s attention and otherwise disrupt our operations and adversely affect our business.

As a part of our business strategy, from time to time we review acquisition prospects that would complement our current product offerings, enhance our design capability or offer other competitive opportunities. As a result of completing acquisitions, we could use a significant portion of our available cash, cash equivalents and short-term investments, issue equity securities that would dilute current stockholders’ percentage ownership, or incur substantial debt or contingent liabilities. Such actions could impact our operating results and the price of our common stock. 

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In addition, we may be unable to identify or complete prospective acquisitions for various reasons, including competition from other companies in the semiconductor industry, the valuation expectations of acquisition candidates and applicable antitrust laws or related regulations. If we are unable to identify and complete acquisitions, we may not be able to successfully expand our business and product offerings.

We cannot guarantee that any future acquisitions will improve our results of operations or that we will otherwise realize the anticipated benefits of any acquisitions. In addition, if we are unsuccessful in integrating any acquired company or business into our operations or if integration is more difficult than anticipated, we may experience disruptions that could harm our business and result in our failure to realize the anticipated benefits of the acquisitions. Some of the risks that may adversely affect our ability to integrate or realize any anticipated benefits from the acquired companies, businesses or assets include those associated with:

• unexpected losses of key employees or customers of the acquired companies or businesses;

• conforming the acquired company’s standards, processes, procedures and controls with our operations;

• coordinating new product and process development;

• hiring additional management and other critical personnel;

• increasing the scope, geographic diversity and complexity of our operations;

• difficulties in consolidating facilities and transferring processes and know-how;

• difficulties in the assimilation of acquired operations, technologies or products;

• the risk of undisclosed liabilities of the acquired businesses and potential legal disputes with founders or stockholders of acquired companies;

• our inability to commercialize acquired technologies;

• the risk that the future business potential as projected is not realized and as a result, we may be required to take an impairment charge related to goodwill or acquired intangibles that would impact our profitability;

• difficulties in assessing the fair value of earn-out arrangements;

• diversion of management’s attention from other business concerns; and

• adverse effects on existing business relationships with customers.

In addition, third parties may be interested in acquiring us. We will consider and discuss such transactions as we deem appropriate. Such potential transactions may diver the attention of management, and cause us to incur various costs and expenses in investigating and evaluating such transactions, whether or not they are consummated.

If we issue additional shares of stock in the future, it may have a dilutive effect on our stockholders.

We may issue additional shares of common stock in the future in order to raise additional capital to fund our global operations or in connection with an acquisition. We also issue RSUs to employees, which convert into shares of common stock upon vesting. Any issuance of our common stock may result in immediate dilution to our stockholders. In addition, the issuance of a significant amount of our common stock may result in additional regulatory requirements, such as stockholder approval.

We compete against many companies with substantially greater financial and other resources, and our market share may be reduced if we are unable to respond to our competitors effectively.

The analog and mixed-signal semiconductor industry is highly competitive, and we expect competitive pressures to continue. Our ability to compete effectively and to expand our business will depend on our ability to continue to recruit applications and design talent, our ability to introduce new products, and our ability to maintain the rate at which we introduce these new products. We compete with domestic and non-domestic semiconductor companies, many of which have substantially greater financial and other resources with which to pursue engineering, manufacturing, marketing, and distribution of their products. We are in direct and active competition, with respect to one or more of our product lines, with many manufacturers of such products, of varying size and financial strength. The number of our competitors has grown due to the expansion of the market segments in which we participate. 

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We cannot assure you that our products will continue to compete favorably, or that we will be successful in the face of increasing competition from new products and enhancements introduced by existing competitors or new companies entering this market, which would materially and adversely affect our results of operations and our financial condition.

If securities or industry analysts downgrade our stock or do not continue to publish research or reports about our business, our stock price and trading volume could decline.

The trading market for our common stock will depend, in part, on the research and reports that industry or securities analysts publish about us or our business. We do not have any control over these analysts. If one or more of the analysts who cover us downgrade our stock, our stock price would likely decline. If one or more of these analysts cease coverage of us or fail to regularly publish reports on us, we could lose visibility in the financial markets, which in turn could cause our stock price or trading volume to decline.

Short positions in our stock could have a substantial impact on the trading price of our stock.

Historically, there have been “short” positions in our common stock. The anticipated downward pressure on our stock price due to actual or anticipated sales of our stock by some institutions or individuals who engage in short sales of our common stock could cause our stock price to decline. Such stock price decreases could encourage further short-sales that could place additional downward pressure on our stock price. This could lead to further increases in the existing short position in our common stock and cause volatility in our stock price. The volatility of our stock may cause the value of a stockholder’s investment to decline rapidly. Additionally, if our stock price declines, it may be more difficult for us to raise capital and may have other adverse effects on our business.

There can be no assurance that we will continue to declare cash dividends at all or in any particular amounts.

We have a dividend program approved by our Board of Directors, pursuant to which we intend to pay quarterly cash dividends on our common stock. The declaration of any future cash dividends is at the discretion of our Board of Directors and will depend on, among other things, our financial condition, results of operations, capital requirements, business conditions, and other factors that our Board of Directors may deem relevant, as well as a determination that cash dividends are in the best interests of our stockholders. Our dividend payments may change from time to time, and we cannot provide assurance that we will continue to declare dividends at all or in any particular amounts. A reduction in or elimination of our dividend payments could have a negative effect on the price of our common stock.

Our worldwide operations are subject to political, economic and health risks and natural disasters, which could have a material adverse effect on our business operations.

Our office in California, the production facilities of our third-party wafer suppliers, our IC testing and manufacturing facilities, a portion of our assembly and research and development activities, and certain other critical business operations are located in or near seismically active regions and are subject to periodic earthquakes. We do not maintain earthquake insurance and could be materially and adversely affected in the event of a major earthquake. Much of our revenue, as well as our manufacturers and assemblers, are concentrated in Asia, particularly in China. Such concentration increases the risk that other natural disasters, labor strikes, terrorism, war, political unrest, epidemics, and/or health advisories could disrupt our operations. For example, the COVID-19 outbreak first identified in China in December 2019 has resulted in significant disruptions in business operations and other economic activities in certain parts of the country.  The World Health Organization has declared the growing disease to be a global health emergency, and the U.S. government has issued travel restrictions to and from China. Any of these events may disrupt our ability to staff our business adequately, could generally disrupt our operations, and specifically, any prolonged health threat from COVID-19 globally could have a material adverse impact on our business operations and results of operations.

In addition, we rely heavily on our internal information and communications systems and on systems or support services from third parties to manage our operations efficiently and effectively. Any of these are subject to failure due to a natural disaster or other disruptions. System-wide or local failures that affect our information processing could have material adverse effects on our business, financial condition, results of operations and cash flows. 

ITEM 1B.  UNRESOLVED STAFF COMMENTS

None.

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ITEM 2.    PROPERTIES

The following table summarizes our significant properties as of December 31, 2019:

Location	Approximate Building Square Footage		Primary Use
Owned:
United States:
Kirkland, Washington		98,000	Principal executive office, research and development, sales and marketing
Livonia, Michigan		40,000	Sales and marketing, research and development
San Jose, California		106,000	Research and development, sales and marketing, administrative
International:
Chengdu, China		150,000	Research and development, administrative
Chengdu, China		60,000	Testing and manufacturing
Hangzhou, China		68,000	Research and development
Shanghai, China		23,000	Sales and marketing
Shenzhen, China		8,000	Sales and marketing
Taipei, Taiwan		47,000	Sales and marketing, research and development
Leased:
Chengdu, China		89,000	Manufacturing operations, inventory warehouse
Barcelona, Spain		12,000	Research and development

We also lease other sales and marketing, and research and development offices in Asia, Europe and the United States. We believe that our existing facilities are adequate for our current operations.

ITEM 3.    LEGAL PROCEEDINGS

We are a party to actions and proceedings in the ordinary course of business, including potential litigation initiated by our stockholders, challenges to the enforceability or validity of our intellectual property, claims that our products infringe on the intellectual property rights of others, and employment matters. These proceedings often involve complex questions of fact and law and may require the expenditure of significant funds and the diversion of other resources to prosecute and defend. We defend ourselves vigorously against any such claims. As of December 31, 2019, there were no material pending legal proceedings to which we were a party.

ITEM 4.    MINE SAFETY DISCLOSURES

Not applicable.

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PART II

ITEM 5.    Market for Registrant’s Common Equity, Related Stockholder Matters and Issuer Purchases of Equity Securities.

Common Stock Information

Our common stock is traded on the Nasdaq Global Select Market under the symbol “MPWR.”

Holders of Common Stock

As of February 19, 2020, there were 23 registered holders of record of our common stock. A substantially greater number of holders of our common stock are “street name” or beneficial holders, whose shares are held by banks, brokers and other financial institutions on their behalf.

Dividend Policy

We currently have a dividend program approved by our Board of Directors, pursuant to which we intend to pay quarterly cash dividends on our common stock. Based on our historical practice, stockholders of record as of the last business day of the quarter are entitled to receive the quarterly cash dividends when and if declared by our Board of Directors, which are payable to the stockholders in the following month. 

The declaration of any future cash dividends is at the discretion of our Board of Directors and will depend on, among other things, our financial condition, results of operations, capital requirements, business conditions and other factors that our Board of Directors may deem relevant, as well as a determination that cash dividends are in the best interests of the stockholders.

Stock Performance Graph

The following graph compares the cumulative five-year total return on our common stock relative to the cumulative total returns of the Nasdaq Composite Index and the PHLX Semiconductor Sector Index. An investment of $100 is assumed to have been made in our common stock on December 31, 2014 and its performance relative to the performance of a similar investment in the two indexes is shown through December 31, 2019, assuming the reinvestment of dividends. Historic stock performance is not indicative of future performance.

The information contained in this stock performance graph section shall not be deemed to be “soliciting material,” or “filed” or incorporated by reference in future filings with the SEC, or subject to the liabilities of Section 18 of the Securities Exchange Act of 1934, except to the extent that we specifically incorporate it by reference into a document filed under the Securities Act of 1933 or the Securities Exchange Act of 1934.

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ITEM 6.    SELECTED FINANCIAL DATA

The following selected consolidated financial data should be read in conjunction with “Management’s Discussion and Analysis of Financial Condition and Results of Operations” and the consolidated financial statements and the notes thereto included elsewhere in this Annual Report on Form 10-K to fully understand factors that may affect the comparability of the information presented below. We derived the selected consolidated balance sheet data as of December 31, 2019 and 2018, and the consolidated statement of operations data for the years ended December 31, 2019, 2018 and 2017 from our audited consolidated financial statements and accompanying notes included in this Annual Report on Form 10-K. The consolidated balance sheet data as of December 31, 2017, 2016 and 2015, and the consolidated statement of operations data for the years ended December 31, 2016 and 2015 are derived from our audited consolidated financial statements which are not included in this report. Operating results for any year are not necessarily indicative of results to be expected for any future periods.

Consolidated Statement of Operations Data:

	Year Ended December 31,
	2019		2018		2017		2016			2015
	(in thousands, except per share amounts)
Revenue	$	627,921	$	582,382	$	470,929	$	388,665		$	333,067
Cost of revenue		281,596		259,714		212,646		177,792			152,898
Gross profit		346,325		322,668		258,283		210,873			180,169
Operating expenses:
Research and development		107,757		93,455		82,359		73,643			65,787
Selling, general and administrative		133,542		113,803		97,257		83,012			72,312
Litigation expense (benefit), net		2,464		1,922		1,243		(229	)		1,000
Total operating expenses		243,763		209,180		180,859		156,426			139,099
Income from operations		102,562		113,488		77,424		54,447			41,070
Interest and other income, net		10,558		4,994		5,520		2,817			1,421
Income before income taxes		113,120		118,482		82,944		57,264			42,491
Income tax expense		4,281		13,214		17,741		4,544			7,319
Net income	$	108,839	$	105,268	$	65,203	$	52,720		$	35,172
Net income per share:
Basic	$	2.52	$	2.49	$	1.58	$	1.30		$	0.89
Diluted	$	2.38	$	2.36	$	1.50	$	1.26		$	0.86
Weighted-average shares outstanding:
Basic		43,165		42,247		41,350		40,436			39,470
Diluted		45,763		44,602		43,578		41,915			40,869
Cash dividends declared per common share	$	1.60	$	1.20	$	0.80	$	0.80		$	0.80

Consolidated Balance Sheet Data:

	December 31,
	2019		2018		2017		2016		2015
	(in thousands)
Cash and cash equivalents	$	172,960	$	172,704	$	82,759	$	112,703	$	90,860
Short-term investments	$	282,437	$	204,577	$	216,331	$	155,521	$	144,103
Total assets	$	956,375	$	793,432	$	652,569	$	511,126	$	431,285
Common stock and additional paid-in capital	$	549,517	$	450,908	$	376,586	$	315,969	$	265,763
Total stockholders' equity	$	773,491	$	640,093	$	522,007	$	431,116	$	368,516
Working capital	$	556,981	$	500,371	$	383,253	$	330,063	$	288,645

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ITEM 7.    MANAGEMENT’S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS

The following discussion should be read in conjunction with the consolidated financial statements and related notes which appear under Item 8 in this Annual Report on Form 10-K.

Overview

We are a leading semiconductor company that designs, develops and markets high-performance power solutions. Incorporated in 1997, MPS’s core strengths include deep system-level and applications knowledge, strong analog design expertise and an innovative proprietary process technology. These combined strengths enable MPS to deliver highly integrated monolithic products that offer energy-efficient, cost-effective, easy-to-use solutions for systems found in computing and storage, automotive, industrial, communications and consumer applications. Our mission is to reduce total energy consumption in our customers’ systems with green, practical and compact solutions. We believe that we differentiate ourselves by offering solutions that are more highly integrated, smaller in size, more energy-efficient, more accurate with respect to performance specifications and, consequently, more cost-effective than many competing solutions. We plan to continue to introduce new products within our existing product families, as well as in new innovative product categories.

We operate in the cyclical semiconductor industry where there is seasonal demand for certain products. We are not immune from current and future industry downturns, but we have targeted product and market areas that we believe have the ability to offer above average industry performance over the long term.

We work with third parties to manufacture and assemble our ICs. This has enabled us to limit our capital expenditures and fixed costs, while focusing our engineering and design resources on our core strengths.

Following the introduction of a product, our sales cycle generally takes a number of quarters after we receive an initial customer order for a new product to ramp up. Typical lead times for orders are generally 8 to 16 weeks. These factors, combined with the fact that orders in the semiconductor industry can typically be cancelled or rescheduled without significant penalty to the customer, make the forecasting of our orders and revenue difficult.

We derive most of our revenue from sales through distribution arrangements and direct sales to customers in Asia, where our products are incorporated into end-user products. Our revenue from direct or indirect sales to customers in Asia was 89%, 88% and 89% for the years ended December 31, 2019, 2018 and 2017, respectively. We derive a majority of our revenue from the sales of our DC to DC converter products which serve the computing and storage, automotive, industrial, communications and consumer markets. We believe our ability to achieve revenue growth will depend, in part, on our ability to develop new products, enter new market segments, gain market share, manage litigation risk, diversify our customer base and continue to secure manufacturing capacity.

Critical Accounting Policies and Estimates

Our discussion and analysis of our financial condition and results of operations are based upon our consolidated financial statements, which have been prepared in accordance with generally accepted accounting principles in the U.S. The preparation of these financial statements requires us to make estimates and judgments that affect the reported amount of assets, liabilities, revenue and expenses, and related disclosure of contingent assets and liabilities. We evaluate our estimates on an on-going basis, including those related to revenue recognition, stock-based compensation, inventories, income taxes and contingencies. We base our estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making the judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Estimates and judgments used in the preparation of our financial statements are, by their nature, uncertain and unpredictable, and depend upon, among other things, many factors outside of our control, such as demand for our products and economic conditions. Accordingly, our estimates and judgments may prove to be incorrect and actual results may differ, perhaps significantly, from these estimates.

We believe the following critical accounting policies reflect our more significant judgments used in the preparation of our consolidated financial statements.

Revenue Recognition 

We generate revenue primarily from product sales, which include assembled and tested integrated circuits, as well as dies in wafer form. These product sales were 99%, 98% and 98% of our total revenue for the years ended December 31, 2019, 2018 and 2017, respectively. The remaining revenue primarily includes royalty revenue from licensing arrangements and revenue from wafer testing services performed for third parties, which have not been significant in all periods presented.

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We recognize revenue from product sales when we satisfy a performance obligation by transferring control of the promised goods or services to our customers, in an amount that reflects the consideration we expect to be entitled to in exchange for those goods or services.

Product sales consist of a single performance obligation that we satisfy at a point in time. We recognize product revenue from distributors and direct end customers when the following events have occurred: (a) we have transferred physical possession of the products, (b) we have a present right to payment, (c) the customer has legal title to the products, and (d) the customer bears significant risks and rewards of ownership of the products. In accordance with the shipping terms specified in the contracts, these criteria are generally met when the products are shipped from our facilities (such as the “Ex Works” shipping term) or delivered to the customers’ locations (such as the “Delivered Duty Paid” shipping term).

Under certain consignment agreements, revenue is not recognized when the products are shipped and delivered to be held at customers’ designated locations because we continue to control the products and retain ownership, and the customers do not have an unconditional obligation to pay. We recognize revenue when the customers consume the products from the consigned inventory locations or, in some cases, after a 60-day period from the delivery date has passed, at which time control transfers to the customers and we invoice them for payment.

We account for price adjustment and stock rotation rights as variable consideration that reduces the transaction price, and recognize that reduction in the same period the associated revenue is recognized. Three U.S.-based distributors have price adjustment rights when they sell our products to their end customers at a price that is lower than the distribution price invoiced by us. When we receive claims from the distributors that products have been sold to the end customers at the lower price, we issue the distributors credit memos for the price adjustments. We estimate the price adjustments using the expected value method based on an analysis of historical claims, at both the distributor and product level, as well as an assessment of any known trends of product sales mix. Other U.S. distributors and non-U.S. distributors, which make up the majority of our total sales to distributors, do not have price adjustment rights. We record a credit against accounts receivable for the estimated price adjustments, with a corresponding reduction to revenue.

Certain distributors have limited stock rotation rights that permit the return of a small percentage of the previous six months’ purchases in accordance with the contract terms. We estimate the stock rotation returns using the expected value method based on an analysis of historical returns, and the current level of inventory in the distribution channel. We record a liability for the stock rotation reserve, with a corresponding reduction to revenue. In addition, we recognize an asset for product returns which represents the right to recover products from the customers related to stock rotations, with a corresponding reduction to cost of revenue.

We pay sales commissions based on the achievement of pre-determined product sales targets. We have elected the practical expedient to expense sales commissions as incurred because the amortization period would have been one year or less. 

Inventory Valuation

We value our inventories at the lower of the standard cost (which approximates actual cost on a first-in, first-out basis) or their current estimated net realizable value. We write down excess and obsolete inventories based on assumptions about future demand and market conditions. If actual demand or market conditions are less favorable than those projected by management, additional inventory write-downs may be required. Conversely, if actual demand or market conditions are more favorable, inventories may be sold that were previously written down. 

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Accounting for Income Taxes 

We recognize federal, state and foreign current tax liabilities or assets based on our estimate of taxes payable or refundable in the current fiscal year by tax jurisdiction. We also recognize federal, state and foreign deferred tax assets or liabilities for our estimate of future tax effects attributable to temporary differences and carryforwards. We record a valuation allowance to reduce any deferred tax assets by the amount of any tax benefits that, based on available evidence and judgment, are not expected to be realized.

Our calculation of current and deferred tax assets and liabilities is based on certain estimates and judgments and involves dealing with uncertainties in the application of complex tax laws. Our estimates of current and deferred tax assets and liabilities may change based, in part, on added certainty, finality or uncertainty to an anticipated outcome, changes in accounting or tax laws in the U.S. or foreign jurisdictions where we operate, or changes in other facts or circumstances. In addition, we recognize liabilities for potential U.S. and foreign income tax for uncertain income tax positions taken on our tax returns if it has less than a 50% likelihood of being sustained. If we determine that payment of these amounts is unnecessary or if the recorded tax liability is less than our current assessment, we may be required to recognize an income tax benefit or additional income tax expense in our financial statements in the period such determination is made. We have calculated our uncertain tax positions which were attributable to certain estimates and judgments.

As of December 31, 2019 and 2018, we had a valuation allowance of $15.4 million and $13.0 million, respectively, attributable to management’s determination that it is more likely than not that certain deferred tax assets will not be fully realized. In the event we determine that it is more likely than not that we would be able to realize the deferred tax assets in the future in excess of our net recorded amount, an adjustment to the valuation allowance for the deferred tax assets would increase income in the period such determination was made. Likewise, should it be determined that additional amounts of the net deferred tax assets will not be realized in the future, an adjustment to increase the deferred tax assets valuation allowance will be charged to income in the period such determination is made.

Contingencies

We are a party to actions and proceedings in the ordinary course of business, including potential litigation regarding our stockholders and our intellectual property, challenges to the enforceability or validity of our intellectual property, claims that our products infringe on the intellectual property rights of others, and employment matters. The pending proceedings involve complex questions of fact and law and will require the expenditure of significant funds and the diversion of other resources to prosecute and defend. In addition, from time to time, we become aware that we are subject to other contingent liabilities. When this occurs, we will evaluate the appropriate accounting for the potential contingent liabilities to determine whether a contingent liability should be recorded. In making this determination, management may, depending on the nature of the matter, consult with internal and external legal counsel and technical experts. Based on the facts and circumstances in each matter, we use our judgment to determine whether it is probable that a contingent loss has occurred and whether the amount of such loss can be estimated. If we determine a loss is probable and estimable, we record a contingent loss. In determining the amount of a contingent loss, we take into account advice received from experts for each specific matter regarding the status of legal proceedings, settlement negotiations, prior case history and other factors. Should the judgments and estimates made by management need to be adjusted as additional information becomes available, we may need to record additional contingent losses that could materially and adversely impact our results of operations. Alternatively, if the judgments and estimates made by management are adjusted, for example, if a particular contingent loss does not occur, the contingent loss recorded would be reversed which could result in a favorable impact on our results of operations.

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Stock-Based Compensation

We measure the cost of employee services received in exchange for an award of equity instruments based on the grant-date fair value of the award. The fair value of RSUs with service conditions or performance conditions is based on the grant date share price. The fair value of shares issued under the employee stock purchase plan (“ESPP”) and RSUs with a purchase price feature is estimated using the Black-Scholes model. The fair value of RSUs with market conditions, as well as RSUs containing both market and performance conditions, is estimated using a Monte Carlo simulation model. 

Compensation expense related to awards with service conditions is recorded on a straight-line basis over the requisite service period. Compensation expense related to awards subject to market or performance conditions is recognized over the requisite service period for each separately vesting tranche. For awards with only market conditions, compensation expense is not reversed if the market conditions are not satisfied. For awards with performance conditions, as well as awards containing both market and performance conditions, we recognize compensation expense when the performance goals are achieved, or when it becomes probable that the performance goals will be achieved. Management performs the probability assessment on a quarterly basis by reviewing external factors, such as macroeconomic conditions and the analog industry revenue forecasts, and internal factors, such as our business and operational objectives and revenue forecasts. Changes in the probability assessment of achievement of the performance conditions are accounted for in the period of change by recording a cumulative catch-up adjustment as if the new estimate had been applied since the service inception date. If the projected achievement was revised upward or if the actual results were higher than the projected achievement, additional compensation expense would be recorded for the awards due to the cumulative catch-up adjustment, which would have an adverse impact on our results of operations. Conversely, if the projected achievement was revised downward or if the actual results were lower than the projected achievement, previously accrued compensation expense would be reversed for the awards, which would have a favorable impact on our results of operations. As a result, our stock-based compensation expense is subject to volatility and may fluctuate significantly each quarter due to changes in our probability assessment of achievement of the performance conditions or actual results being different from projections made by management.

We account for forfeitures of equity awards when they occur.

Recent Accounting Pronouncements

Refer to Note 1 to our consolidated financial statements regarding recently adopted accounting pronouncements and recent accounting pronouncements not yet adopted as of December 31, 2019.

Results of Operations

The following table summarizes our results of operations:

	Year Ended December 31,
	2019				2018				2017
	(in thousands, except percentages)
Revenue	$	627,921	100.0	%	$	582,382	100.0	%	$	470,929	100.0	%
Cost of revenue		281,596	44.8			259,714	44.6			212,646	45.2
Gross profit		346,325	55.2			322,668	55.4			258,283	54.8
Operating expenses:
Research and development		107,757	17.2			93,455	16.0			82,359	17.5
Selling, general and administrative		133,542	21.3			113,803	19.5			97,257	20.7
Litigation expense		2,464	0.4			1,922	0.4			1,243	0.2
Total operating expenses		243,763	38.9			209,180	35.9			180,859	38.4
Income from operations		102,562	16.3			113,488	19.5			77,424	16.4
Interest and other income, net		10,558	1.7			4,994	0.9			5,520	1.2
Income before income taxes		113,120	18.0			118,482	20.4			82,944	17.6
Income tax expense		4,281	0.7			13,214	2.3			17,741	3.8
Net income	$	108,839	17.3	%	$	105,268	18.1	%	$	65,203	13.8	%

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Revenue

The following table summarizes our revenue by end market:

	Year Ended December 31,															Change
End Market	2019		% of Revenue			2018		% of Revenue			2017		% of Revenue			From 2018 to 2019			From 2017 to 2018
	(in thousands, except percentages)
Computing and storage	$	189,215		30.1	%	$	159,121		27.3	%	$	100,782		21.4	%		18.9	%		57.9	%
Automotive		90,303		14.4			80,078		13.8			53,888		11.4			12.8	%		48.6	%
Industrial		99,381		15.8			88,472		15.2			62,896		13.4			12.3	%		40.7	%
Communications		84,794		13.5			70,589		12.1			63,606		13.5			20.1	%		11.0	%
Consumer		164,228		26.2			184,122		31.6			189,757		40.3			(10.8	)%		(3.0	)%
Total	$	627,921		100.0	%	$	582,382		100.0	%	$	470,929		100.0	%		7.8	%		23.7	%

Revenue for the year ended December 31, 2019 was $627.9 million, an increase of $45.5 million, or 7.8%, from $582.4 million for the year ended December 31, 2018. This increase was driven by higher sales in all of our end markets except for the consumer market. Overall unit shipments increased by 8% due to higher market demand and average sales prices were essentially flat compared to the same period in 2018.

For the year ended December 31, 2019, revenue from the communications market increased $14.2 million, or 20.1%, from the same period in 2018. This increase was primarily driven by higher demand in infrastructure sales including the 5G network. Revenue from the computing and storage market increased $30.1 million, or 18.9%, from the same period in 2018. This increase was primarily driven by strength in the high-performance notebook and cloud computing markets, which was partially offset by lower demand in the solid-state drive storage market. Revenue from the automotive market increased $10.2 million, or 12.8%, from the same period in 2018. This increase was primarily driven by higher sales of products for infotainment applications. Revenue from the industrial market increased $10.9 million, or 12.3%, from the same period in 2018. This increase was primarily driven by higher sales in power source and security products. Revenue from the consumer market decreased $19.9 million, or 10.8%, from the same period in 2018. This decrease was primarily due to a decrease in demand for high volume consumer-related products, as well as lower sales from specialty lighting, chargers and gaming products. This decrease was partially offset by higher demand for wearables and home appliance products. 

Revenue for the year ended December 31, 2018 was $582.4 million, an increase of $111.5 million, or 23.7%, from $470.9 million for the year ended December 31, 2017. This increase was driven by higher sales in all of our end markets except for the consumer market. Overall unit shipments increased by 19% due to higher market demand and average sales prices increased by 4% from the same period in 2017.

For the year ended December 31, 2018, revenue from the computing and storage market increased $58.3 million, or 57.9%, from the same period in 2017. This increase was primarily driven by strength in the solid-state drive storage, cloud computing and high-performance notebook markets. Revenue from the automotive market increased $26.2 million, or 48.6%, from the same period in 2017. This increase was primarily driven by higher sales of products for infotainment, safety and connectivity applications. Revenue from the industrial market increased $25.6 million, or 40.7%, from the same period in 2017. This increase was primarily driven by higher sales in power source, security and meter products. Revenue from the communications market increased $7.0 million, or 11.0%, from the same period in 2017. This increase was primarily driven by higher demand in networking applications. Revenue from the consumer market decreased $5.6 million, or 3.0%, from the same period in 2017. This decrease was primarily due to softness in demand for high volume consumer-related products, particularly those sold in the greater China region. This decrease was partially offset by higher demand for products related to home appliance, specialty lighting and internet-of-things applications.

Cost of Revenue and Gross Margin 

Cost of revenue primarily consists of costs incurred to manufacture, assemble and test our products, as well as warranty costs, inventory-related and other overhead costs, and stock-based compensation expenses.

	Year Ended December 31,									Change
	2019			2018			2017			From 2018 to 2019			From 2017 to 2018
	(in thousands, except percentages)
Cost of revenue	$	281,596		$	259,714		$	212,646			8.4	%		22.1	%
As a percentage of revenue		44.8	%		44.6	%		45.2	%
Gross profit	$	346,325		$	322,668		$	258,283			7.3	%		24.9	%
Gross margin		55.2	%		55.4	%		54.8	%

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Cost of revenue was $281.6 million, or 44.8% of revenue, for the year ended December 31, 2019, and $259.7 million, or 44.6% of revenue, for the year ended December 31, 2018. The $21.9 million increase in cost of revenue was primarily due to an 8% increase in overall unit shipments and a 6% increase in the average direct cost of units shipped. The increase in cost of revenue was partially offset by a decrease in inventory write-downs and warranty expenses.

Gross margin was 55.2% for the year ended December 31, 2019, compared with 55.4% for the year ended December 31, 2018. The decrease in gross margin was primarily due to increased sales of lower margin products, which was partially offset by lower inventory write-downs and warranty expenses as a percentage of revenue.

Cost of revenue was $259.7 million, or 44.6% of revenue, for the year ended December 31, 2018, and $212.6 million, or 45.2% of revenue, for the year ended December 31, 2017. The $47.1 million increase in cost of revenue was primarily due to a 19% increase in overall unit shipments, which was partially offset by a 1% decrease in the average direct cost of units shipped. The increase in cost of revenue was also driven by a $10.5 million increase in inventory write-downs, a $2.1 million increase in warranty expenses, and a $1.7 million increase in manufacturing overhead costs, which was partially offset by a $1.2 million decrease in amortization expense as certain intangible assets were fully amortized in 2018.

Gross margin was 55.4% for the year ended December 31, 2018, compared with 54.8% for the year ended December 31, 2017. The increase in gross margin was primarily due to increased sales of higher margin products and lower manufacturing overhead costs as a percentage of revenue, which was partially offset by higher inventory write-downs as a percentage of revenue.

Research and Development (“R&D”)

R&D expenses primarily consist of salary and benefit expenses, bonuses, stock-based compensation and deferred compensation for design and product engineers, expenses related to new product development and supplies, and facility costs.   

	Year Ended December 31,									Change
	2019			2018			2017			From 2018 to 2019			From 2017 to 2018
	(in thousands, except percentages)
R&D expenses	$	107,757		$	93,455		$	82,359			15.3	%		13.5	%
As a percentage of revenue		17.2	%		16.0	%		17.5	%

R&D expenses were $107.8 million, or 17.2% of revenue, for the year ended December 31, 2019, and $93.5 million, or 16.0% of revenue, for the year ended December 31, 2018. The $14.3 million increase in R&D expenses was primarily due to an increase of $4.6 million in compensation expenses, which include salary, benefits and bonuses, an increase of $3.6 million in stock-based compensation expenses, which were mainly associated with performance-based equity awards, an increase of $2.4 million in new product development expenses, and an increase of $1.8 million in expenses related to changes in the value of the deferred compensation plan liabilities. Our R&D headcount was 839 employees as of December 31, 2019, compared with 710 employees as of December 31, 2018. 

R&D expenses were $93.5 million, or 16.0% of revenue, for the year ended December 31, 2018, and $82.4 million, or 17.5% of revenue, for the year ended December 31, 2017. The $11.1 million increase in R&D expenses was primarily due to an increase of $6.9 million in compensation expenses, which include salary, benefits and bonuses, an increase of $2.4 million in laboratory supplies, an increase of $1.4 million in new product development expenses, and an increase of $1.2 million in stock-based compensation expenses mainly associated with performance-based equity awards. These increases were partially offset by an increase of $1.4 million in income related to changes in the value of the deferred compensation plan liabilities. Our R&D headcount was 710 employees as of December 31, 2018, compared with 629 employees as of December 31, 2017. 

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Selling, General and Administrative (“SG&A”)

SG&A expenses primarily include salary and benefit expenses, bonuses, stock-based compensation and deferred compensation for sales, marketing and administrative personnel, sales commissions, travel expenses, facilities costs, and professional service fees. 

	Year Ended December 31,									Change
	2019			2018			2017			From 2018 to 2019			From 2017 to 2018
	(in thousands, except percentages)
SG&A expenses	$	133,542		$	113,803		$	97,257			17.3	%		17.0	%
As a percentage of revenue		21.3	%		19.5	%		20.7	%

SG&A expenses were $133.5 million, or 21.3% of revenue, for the year ended December 31, 2019, and $113.8 million, or 19.5% of revenue, for the year ended December 31, 2018. The $19.7 million increase in SG&A expenses was primarily due to an increase of $14.0 million in stock-based compensation expenses, which were mainly associated with performance-based equity awards, an increase of $2.8 million in compensation expenses, which include salary, benefits and bonuses, and an increase of $2.7 million in expenses related to changes in the value of the deferred compensation plan liabilities. Our SG&A headcount was 503 employees as of December 31, 2019, compared with 433 employees as of December 31, 2018.  

SG&A expenses were $113.8 million, or 19.5% of revenue, for the year ended December 31, 2018, and $97.3 million, or 20.7% of revenue, for the year ended December 31, 2017. The $16.5 million increase in SG&A expenses was primarily due to an increase of $6.6 million in stock-based compensation expenses mainly associated with performance-based equity awards, an increase of $5.0 million in compensation expenses, which include salary, benefits and bonuses, and an increase of $4.0 million in commission expenses driven by higher revenue. These increases were partially offset by an increase of $2.0 million in income related to changes in the value of the deferred compensation plan liabilities. Our SG&A headcount was 433 employees as of December 31, 2018, compared with 389 employees as of December 31, 2017. 

Litigation Expense

Litigation expense was $2.5 million for the year ended December 31, 2019, compared with $1.9 million for the year ended December 31, 2018. The increase was primarily due to an ongoing lawsuit in which we are the plaintiff.

Litigation expense was $1.9 million for the year ended December 31, 2018, compared with $1.2 million for the year ended December 31, 2017. The increase was primarily due to an ongoing lawsuit in which we are the plaintiff.

Interest and Other Income, Net

Interest and other income, net, was $10.6 million for the year ended December 31, 2019, compared with $5.0 million for the year ended December 31, 2018. The increase was primarily due to an increase of $4.8 million in income related to changes in the value of the deferred compensation plan investments, an increase of $1.0 million in interest income as a result of higher investment balances and yields, and a decrease of $0.6 million in amortization of premium on available-for-sale securities. These favorable changes were partially offset by an increase of $1.3 million in foreign currency exchange losses.

Interest and other income, net, was $5.0 million for the year ended December 31, 2018, compared with $5.5 million for the year ended December 31, 2017. The decrease was primarily due to an increase of $3.6 million in expenses related to changes in the value of the deferred compensation plan investments. This decrease was partially offset by an increase of $1.5 million in foreign currency exchange gains, an increase of $1.0 million in interest income as a result of higher investment balances and yields, and a decrease of $0.6 million in amortization of premium on available-for-sale securities.

Income Tax Provision

The income tax expense for the year ended December 31, 2019 was $4.3 million, or 3.8% of pre-tax income. The effective tax rate differed from the federal statutory rate primarily due to foreign income from our subsidiaries in Bermuda and China being taxed at lower statutory tax rates, the impact of certain tax credits and excess tax benefits from stock-based compensation. The decrease in the effective tax rate relative to the federal statutory rate was partially offset by the inclusion of the global intangible low-taxed income (“GILTI”) tax.

The income tax expense for the year ended December 31, 2018 was $13.2 million, or 11.2% of pre-tax income. The effective tax rate differed from the federal statutory rate primarily due to foreign income from our subsidiaries in Bermuda and China being taxed at lower statutory tax rates. The decrease in the effective tax rate relative to the federal statutory rate was partially offset by the inclusion of the GILTI tax.

The income tax expense for the year ended December 31, 2017 was $17.7 million, or 21.4% of pre-tax income. The effective tax rate differed from the federal statutory rate primarily due to foreign income from our subsidiaries in Bermuda and China being taxed at lower rates and the release of the U.S. valuation allowance. The decrease in the effective tax rate relative to the federal statutory rate was partially impacted by the effects of the 2017 Tax Act, including the remeasurement of deferred taxes and the one-time deemed repatriation transition tax. 

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See Note 12 of the Notes to Consolidated Financial Statements included in Part II, Item 8 of this Annual Report on Form 10-K for further discussion.

Liquidity and Capital Resources

	December 31,
	2019			2018
	(in thousands, except percentages)
Cash and cash equivalents	$	172,960		$	172,704
Short-term investments		282,437			204,577
Total cash, cash equivalents and short-term investments	$	455,397		$	377,281
Percentage of total assets		47.6	%		47.6	%
Total current assets	$	655,206		$	580,810
Total current liabilities		(98,225	)		(80,439	)
Working capital	$	556,981		$	500,371

As of December 31, 2019, we had cash and cash equivalents of $173.0 million and short-term investments of $282.4 million, compared with cash and cash equivalents of $172.7 million and short-term investments of $204.6 million as of December 31, 2018. As of December 31, 2019, $99.5 million of cash and cash equivalents and $186.7 million of short-term investments were held by our international subsidiaries. For the year ended December 31, 2019, we repatriated $75 million of cash from our Bermuda subsidiary to the U.S. The proceeds were primarily used to fund real estate purchases and cash dividend payments. We may repatriate additional cash from our Bermuda subsidiary to fund our expenditures in future periods. We anticipate that earnings from other foreign subsidiaries will continue to be indefinitely reinvested.

The significant components of our working capital are cash and cash equivalents, short-term investments, accounts receivable, inventories and other current assets, reduced by accounts payable, accrued compensation and related benefits, and other accrued liabilities. As of December 31, 2019, we had working capital of $557.0 million, compared with working capital of $500.4 million as of December 31, 2018. The $56.6 million increase in working capital was due to a $74.4 million increase in current assets, which was partially offset by a $17.8 million increase in current liabilities. The increase in current assets was primarily due to an increase in short-term investments and other current assets, which was partially offset by a decrease in inventories. The increase in current liabilities was primarily due to an increase in accounts payable, accrued compensation and related benefits and other accrued liabilities.

Summary of Cash Flows 

The following table summarizes our cash flow activities:

	Year Ended December 31,
	2019			2018			2017
	(in thousands)
Net cash provided by operating activities	$	216,303		$	141,451		$	133,821
Net cash used in investing activities		(167,112	)		(14,740	)		(134,060	)
Net cash used in financing activities		(48,050	)		(34,559	)		(31,325	)
Effect of change in exchange rates		(883	)		(2,208	)		1,625
Net increase (decrease) in cash, cash equivalents and restricted cash	$	258		$	89,944		$	(29,939	)

For the year ended December 31, 2019, net cash provided by operating activities was $216.3 million, primarily due to our net income adjusted for certain non-cash items, including depreciation and amortization and stock-based compensation, and a net increase of $17.8 million from the changes in our operating assets and liabilities. The increase in other assets was primarily due to an increase in prepaid income taxes and an increase in certain tax withholding proceeds receivable related to RSUs that vested at the end of the year. The increase in other accrued liabilities was primarily driven by an increase in employee contributions to the deferred compensation plan. The decrease in inventories was primarily driven by a decrease in wafer and die purchases. 

37

For the year ended December 31, 2018, net cash provided by operating activities was $141.5 million, primarily due to our net income adjusted for certain non-cash items, including depreciation and amortization and stock-based compensation, and a net decrease of $37.5 million from the changes in our operating assets and liabilities. The increase in accounts receivable was primarily driven by increased sales. The increase in inventories was primarily driven by an increase in strategic wafer and die inventories as well as an increase in finished goods to meet current demand and future growth. The increase in accrued liabilities was primarily driven by an increase in employee contributions to the deferred compensation plan.

For the year ended December 31, 2017, net cash provided by operating activities was $133.8 million, primarily due to our net income adjusted for certain non-cash items, including depreciation and amortization, stock-based compensation and deferred taxes, and a net increase of $15.7 million from the changes in our operating assets and liabilities. The increase in deferred taxes was primarily due to the release of the U.S. valuation allowance, partially offset by the remeasurement of the deferred tax balance in the fourth quarter of 2017 as a result of the 2017 Tax Act. The increase in accounts receivable was primarily driven by higher sales. The increase in inventories was primarily driven by an increase in strategic wafer and die inventories as well as an increase in finished goods to meet current demand and future growth. The increase in accounts payable was primarily driven by increased inventory and capital asset purchases to meet future demand. The increase in accrued liabilities was primarily driven by an increase in employee contributions to the deferred compensation plan and warranty expenses. The increase in income tax liabilities was primarily driven by the one-time deemed repatriation transition tax liability recorded in the fourth quarter of 2017. 

For the year ended December 31, 2019, net cash used in investing activities was $167.1 million, primarily due to purchases of property and equipment of $95.8 million, net purchases of short-term investments of $76.8 million and net contributions to the deferred compensation plan of $3.1 million. These cash outflows were partially offset by proceeds from sales of property and equipment of $9.3 million. For the year ended December 31, 2018, net cash used in investing activities was $14.7 million, primarily due to purchases of property and equipment of $22.5 million and net contributions to the deferred compensation plan of $4.1 million, which was partially offset by net sales of investments of $11.9 million. For the year ended December 31, 2017, net cash used in investing activities was $134.1 million, primarily due to purchases of property and equipment of $65.8 million, net purchases of short-term investments of $63.0 million, and net contributions to the deferred compensation plan of $5.3 million.

For the year ended December 31, 2019, we funded the purchases of properties in Kirkland, Washington and Livonia, Michigan for $57.4 million. We did not purchase any significant properties for the year ended December 31, 2018. For the year ended December 31, 2017, we funded the purchases of land in Kirkland, Washington, office space in Shanghai and Hangzhou, China, and land and office space in Taipei, Taiwan for $53.8 million.

For the year ended December 31, 2019, net cash used in financing activities was $48.1 million, primarily reflecting $67.3 million used to pay dividends to our stockholders and dividend equivalents to our employees who hold RSUs, which was partially offset by $19.9 million of cash proceeds from the vesting of RSUs and the issuance of shares through our ESPP. For the year ended December 31, 2018, net cash used in financing activities was $34.6 million, primarily reflecting $47.5 million used to pay dividends to our stockholders and dividend equivalents to our employees who hold RSUs, which was partially offset by $13.6 million of cash proceeds from the vesting of RSUs and the issuance of shares through our ESPP. For the year ended December 31, 2017, net cash used in financing activities was $31.3 million, primarily reflecting $33.9 million used to pay dividends to our stockholders and dividend equivalents to our employees who hold RSUs, which was partially offset by $2.9 million of cash proceeds from stock option exercises and the issuance of shares through our ESPP.

In February 2020, our Board of Directors approved an increase in our quarterly cash dividends from $0.40 per share to $0.50 per share.

We anticipate that cash used for future dividends and dividend equivalent payments, as well as payments for the one-time deemed repatriation transition tax and other expenditures, will come from our domestic cash, cash generated from ongoing U.S. operations, and cash repatriated from our Bermuda subsidiary. Earnings from other foreign subsidiaries will continue to be indefinitely reinvested.

Although cash requirements will fluctuate based on the timing and extent of many factors such as those discussed above, we believe that cash generated from operations, together with the liquidity provided by existing cash balances and short-term investments, will be sufficient to satisfy our liquidity requirements for the next 12 months. 

In the future, in order to strengthen our financial position, respond to changes in our circumstance or unforeseen events or conditions, or fund our growth, we may need to discontinue paying dividends and dividend equivalents, and may need to raise additional funds by any one or a combination of the following: issuing equity securities, issuing debt or convertible debt securities, incurring indebtedness secured by our assets, or selling certain product lines and/or portions of our business. Accordingly, we cannot ensure that we will continue to pay dividends and dividend equivalents in the future, and there can be no guarantee that we will be able to raise additional funds on terms acceptable to us, or at all.

From time to time, we have engaged in discussions with third parties concerning potential acquisitions of product lines, technologies, businesses and companies, and we continue to consider potential acquisition candidates. Any such transactions could involve the issuance of a significant number of new equity securities, assumptions of debt, and/or payment of cash consideration. We may also be required to raise additional funds to complete any such acquisitions, through either the issuance of equity and debt securities or incurring indebtedness secured by our assets. If we raise additional funds or acquire businesses or technologies through the issuance of equity securities or convertible debt securities, our existing stockholders may experience significant dilution. 

38

Contractual Obligations 

The following table summarizes our contractual obligations at December 31, 2019:

			Payment Due by Period
	Total		Less Than 1 Year		1 - 3 Years		3 - 5 Years		More Than 5 years
	(in thousands)
Operating lease obligations (1)	$	2,717	$	1,571	$	1,124	$	22	$	-
Outstanding purchase commitments (2)		90,613		79,937		9,826		300		550
Transition tax liability (3)		20,705		1,972		3,944		8,627		6,162
Other long-term obligations (4)		45,930		-		9,304		11,506		25,120
Total	$	159,965	$	83,480	$	24,198	$	20,455	$	31,832

(1) Operating lease obligations represent the undiscounted remaining lease payments. While we have elected not to record short-term leases with a term of 12 months or less at the commencement date on the Consolidated Balance Sheets, the remaining obligations for these leases are included in the table above.

(2) Outstanding purchase commitments represent our obligations with our suppliers and other parties that require the future purchases of goods or services, which primarily consist of wafer and other inventory purchases, assembly and other manufacturing services, construction or purchases of property and equipment, and license arrangements.

(3)	The transition tax liability represents the one-time, mandatory deemed repatriation tax imposed on previously deferred foreign earnings under the 2017 Tax Act. As permitted by the 2017 Tax Act, we have elected to pay the tax liability in installments on an interest-free basis through 2025.
(4)	Other long-term obligations include long-term liabilities reflected on our Consolidated Balance Sheets, which primarily consist of the deferred compensation plan liabilities and accrued dividend equivalents. Because of the uncertainty as to the timing of payments related to our liabilities for unrecognized tax benefits, we have excluded estimated obligations of $18.9 million from the table above.

Off Balance Sheet Arrangements

As of December 31, 2019, we had no off-balance sheet arrangements as defined in Item 303(a)(4) of the Securities and Exchange Commission’s Regulation S-K.

ITEM 7A.    QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISK

Interest Rate Risk

Our cash equivalents and short-term investments are subject to market risk, primarily interest rate and credit risk. Our investments are managed by outside professional managers within investment guidelines set by management and approved by our Board of Directors. Such guidelines include security type, credit quality and maturity and are intended to limit market risk by restricting our investments to high quality debt instruments with relatively short-term maturities. Based on our investment positions as of December 31, 2019, a 10% decline in interest rates would impact our results of operations by approximately $0.7 million in interest income.

We do not use derivative financial instruments in our investment portfolio. Investments in debt securities are classified as available-for-sale, which are reported at fair value with the unrealized gains or losses being included in accumulated other comprehensive income (loss), a component of stockholders’ equity. When the fair value of an investment is below its amortized cost basis, no realized losses are recognized in our results of operations due to changes in interest rates (i.e., non-credit loss factors) unless we have the intent to sell the securities or it is more likely than not that we will be required to sell the securities before recovery of the entire amortized cost basis.

39

Long-Term Investments

As of December 31, 2019, our holdings in auction-rate securities had a face value of $3.4 million and a fair value of $3.1 million. The decline in the fair value could impact our operating results by $0.2 million if we have the intent to sell the securities, it is more likely than not that we will be required to sell the securities before recovery of the entire amortized cost basis, or the decline in value is related to credit loss factors. An additional 10% decline in the fair value could further impact our operating results by $0.3 million. To date, we have redeemed $40.0 million, or 92% of the original portfolio in these securities, at par without any realized losses.

Foreign Currency Exchange Risk

Our sales outside the United States are primarily transacted in U.S. dollars through our subsidiary in Bermuda. Accordingly, our sales are not generally impacted by foreign currency rate changes. The functional currency of the Company’s offshore operations is generally the local currency, primarily including the Renminbi, the New Taiwan Dollar and the Euro. In addition, we incur foreign currency exchange gains or losses related to certain intercompany transactions between the U.S. and our foreign subsidiaries that are denominated in a currency other than the functional currency. Gains or losses from the settlement and remeasurement of the balances are reported in interest and other income, net. Fluctuations in foreign currency exchange rates have not had a material impact on our results of operations in any of the periods presented.   

40

ITEM 8.     FINANCIAL STATEMENTS AND SUPPLEMENTARY DATA

MONOLITHIC POWER SYSTEMS, INC.

CONSOLIDATED FINANCIAL STATEMENTS

Contents

	Page
Reports of Independent Registered Public Accounting Firm (Ernst & Young LLP)	42
Report of Independent Registered Public Accounting Firm (Deloitte & Touche LLP)	45
Consolidated Balance Sheets	46
Consolidated Statements of Operations	47
Consolidated Statements of Comprehensive Income	48
Consolidated Statements of Stockholders’ Equity	49
Consolidated Statements of Cash Flows	50
Notes to Consolidated Financial Statements	51

41

REPORT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

To the Stockholders and the Board of Directors of Monolithic Power Systems, Inc.

Opinion on the Financial Statements

We have audited the accompanying consolidated balance sheet of Monolithic Power Systems Inc. (the Company) as of December 31, 2019, the related consolidated statements of operations, comprehensive income, stockholders’ equity and cash flows for the year ended December 31, 2019, and the related notes (collectively referred to as the “consolidated financial statements”). In our opinion, the consolidated financial statements present fairly, in all material respects, the financial position of the Company at December 31, 2019, and the results of its operations and its cash flows for the year ended December 31, 2019, in conformity with U.S. generally accepted accounting principles.

We also have audited, in accordance with the standards of the Public Company Accounting Oversight Board (United States) (PCAOB), the Company’s internal control over financial reporting as of December 31, 2019, based on criteria established in Internal Control - Integrated Framework issued by the Committee of Sponsoring Organizations of the Treadway Commission (2013 framework) and our report dated February 28, 2020 expressed an unqualified opinion thereon.

Basis for Opinion

These financial statements are the responsibility of the Company’s management. Our responsibility is to express an opinion on the Company’s financial statements based on our audit. We are a public accounting firm registered with the PCAOB and are required to be independent with respect to the Company in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.

We conducted our audit in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of material misstatement, whether due to error or fraud. Our audit included performing procedures to assess the risks of material misstatement of the financial statements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence regarding the amounts and disclosures in the financial statements. Our audit also included evaluating the accounting principles used and significant estimates made by management, as well as evaluating the overall presentation of the financial statements. We believe that our audit provides a reasonable basis for our opinion.

Critical Audit Matter

The critical audit matter communicated below is a matter arising from the current period audit of the financial statements that was communicated or required to be communicated to the audit committee and that: (1) relates to accounts or disclosures that are material to the financial statements and (2) involved our especially challenging, subjective, or complex judgments. The communication of the critical audit matter does not alter in any way our opinion on the financial statements, taken as a whole, and we are not, by communicating the critical audit matter below, providing a separate opinion on the critical audit matter or on the account or disclosure to which it relates.

42

	Inventory Valuation
Description of the Matter	The Company’s inventories totaled $127.5 million as of December 31, 2019, representing 13.3% of total assets. As explained in Note 1 to the consolidated financial statements, the Company values inventories at the lower of standard cost (which approximates actual cost determined on a first-in first-out basis) and estimated net realizable value in each reporting period. Excess and obsolete inventory is written down to its estimated net realizable value if less than cost.
	Auditing management’s estimates for excess and obsolete inventory involved subjective auditor judgment because management’s assessment of whether a write down is required and the measurement of any excess of cost over net realizable value is judgmental and considers a number of qualitative factors that are affected by market and economic conditions outside the Company’s control. In particular, the excess and obsolete inventory calculations are sensitive to significant assumptions, including demand for the Company’s products, which considers adjustments to sales forecasts for specific product considerations, including but not limited to new product launches and expected industry sales growth.
How We Addressed the Matter in Our Audit	We obtained an understanding, evaluated the design, and tested the operating effectiveness of internal controls over the Company's excess and obsolete inventory reserve process. This included controls over management’s assessment of inventory valuation, including the determination of forecasted usage of inventories and how factors outside of the Company’s control might affect management’s judgment related to the valuation of excess and obsolete inventory.
	Our substantive audit procedures included, among others, evaluating the significant assumptions stated above and testing the completeness and accuracy of the underlying data used in management’s excess and obsolete inventory valuation assessment. We evaluated inventory levels compared to forecasted product demand, historical sales and specific product considerations. We also assessed the historical accuracy of management’s estimates and performed sensitivity analyses over the significant assumptions to evaluate the changes in the excess and obsolete inventory estimates that would result from changes in the underlying assumptions.
/s/ Ernst & Young LLP

We have served as the Company's auditor since 2019.

San Jose, California  

February 28, 2020

43

REPORT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

To the Stockholders and the Board of Directors of Monolithic Power Systems, Inc.

Opinion on Internal Control Over Financial Reporting

We have audited Monolithic Power Systems Inc.’s internal control over financial reporting as of December 31, 2019, based on criteria established in Internal Control – Integrated Framework issued by the Committee of Sponsoring Organizations of the Treadway Commission (2013 framework) (the COSO criteria). In our opinion, Monolithic Power Systems Inc. (the Company) maintained, in all material respects, effective internal control over financial reporting as of December 31, 2019, based on the COSO criteria.

We also have audited, in accordance with the standards of the Public Company Accounting Oversight Board (United States) (PCAOB), the consolidated balance sheet of the Company as of December 31, 2019, the related consolidated statements of operations, comprehensive income, stockholders’ equity and cash flows for the year ended December 31, 2019, and the related notes and our report dated February 28, 2020 expressed an unqualified opinion thereon.

Basis for Opinion

The Company’s management is responsible for maintaining effective internal control over financial reporting and for its assessment of the effectiveness of internal control over financial reporting included in the accompanying Management’s Report on Internal Control over Financial Reporting. Our responsibility is to express an opinion on the Company’s internal control over financial reporting based on our audit. We are a public accounting firm registered with the PCAOB and are required to be independent with respect to the Company in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.

We conducted our audit in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether effective internal control over financial reporting was maintained in all material respects.

Our audit included obtaining an understanding of internal control over financial reporting, assessing the risk that a material weakness exists, testing and evaluating the design and operating effectiveness of internal control based on the assessed risk, and performing such other procedures as we considered necessary in the circumstances. We believe that our audit provides a reasonable basis for our opinion.

Definition and Limitations of Internal Control Over Financial Reporting

A company’s internal control over financial reporting is a process designed to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles. A company’s internal control over financial reporting includes those policies and procedures that (1) pertain to the maintenance of records that, in reasonable detail, accurately and fairly reflect the transactions and dispositions of the assets of the company; (2) provide reasonable assurance that transactions are recorded as necessary to permit preparation of financial statements in accordance with generally accepted accounting principles, and that receipts and expenditures of the company are being made only in accordance with authorizations of management and directors of the company; and (3) provide reasonable assurance regarding prevention or timely detection of unauthorized acquisition, use, or disposition of the company’s assets that could have a material effect on the financial statements.

Because of its inherent limitations, internal control over financial reporting may not prevent or detect misstatements. Also, projections of any evaluation of effectiveness to future periods are subject to the risk that controls may become inadequate because of changes in conditions, or that the degree of compliance with the policies or procedures may deteriorate.

/s/ Ernst & Young LLP

San Jose, California

February 28, 2020

44

REPORT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

To the Stockholders and the Board of Directors of Monolithic Power Systems, Inc.

Opinion on the Financial Statements

We have audited the accompanying consolidated balance sheet of Monolithic Power Systems, Inc. and subsidiaries (the “Company”) as of December 31, 2018, the related consolidated statements of operations, comprehensive income, stockholders’ equity, and cash flows, for each of the two years in the period ended December 31, 2018, and the related notes (collectively referred to as the “financial statements”). In our opinion, the financial statements present fairly, in all material respects, the financial position of the Company as of December 31, 2018, and the results of its operations and its cash flows for each of the two years in the period ended December 31, 2018, in conformity with accounting principles generally accepted in the United States of America.

Basis for Opinion

These financial statements are the responsibility of the Company’s management. Our responsibility is to express an opinion on the Company’s financial statements based on our audits. We are a public accounting firm registered with the PCAOB and are required to be independent with respect to the Company in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.

We conducted our audits in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of material misstatement, whether due to error or fraud. Our audits included performing procedures to assess the risks of material misstatement of the financial statements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence regarding the amounts and disclosures in the financial statements. Our audits also included evaluating the accounting principles used and significant estimates made by management, as well as evaluating the overall presentation of the financial statements. We believe that our audits provide a reasonable basis for our opinion.

/s/ Deloitte & Touche LLP

San Jose, California  

March 1, 2019  

We began serving as the Company’s auditor in 1999.  In 2019 we became the predecessor auditor.

45

MONOLITHIC POWER SYSTEMS, INC.

CONSOLIDATED BALANCE SHEETS

(in thousands, except par value)

	December 31,
	2019			2018
ASSETS
Current assets:
Cash and cash equivalents	$	172,960		$	172,704
Short-term investments		282,437			204,577
Accounts receivable, net		52,704			55,214
Inventories		127,500			136,384
Other current assets		19,605			11,931
Total current assets		655,206			580,810
Property and equipment, net		228,315			150,001
Long-term investments		3,138			3,241
Goodwill		6,571			6,571
Deferred tax assets, net		17,193			16,830
Other long-term assets		45,952			35,979
Total assets	$	956,375		$	793,432
LIABILITIES AND STOCKHOLDERS’ EQUITY
Current liabilities:
Accounts payable	$	27,271		$	22,678
Accrued compensation and related benefits		26,164			18,799
Other accrued liabilities		44,790			38,962
Total current liabilities		98,225			80,439
Income tax liabilities		37,596			34,375
Other long-term liabilities		47,063			38,525
Total liabilities		182,884			153,339
Commitments and contingencies
Stockholders’ equity:
Common stock and additional paid-in capital: $0.001 par value; shares authorized: 150,000; shares issued and outstanding: 43,616 and 42,505, respectively		549,517			450,908
Retained earnings		229,450			194,728
Accumulated other comprehensive loss		(5,476	)		(5,543	)
Total stockholders’ equity		773,491			640,093
Total liabilities and stockholders’ equity	$	956,375		$	793,432

See accompanying notes to consolidated financial statements.

46

MONOLITHIC POWER SYSTEMS, INC.

CONSOLIDATED STATEMENTS OF OPERATIONS

(in thousands, except per share amounts)

	Year Ended December 31,
	2019		2018		2017
Revenue	$	627,921	$	582,382	$	470,929
Cost of revenue		281,596		259,714		212,646
Gross profit		346,325		322,668		258,283
Operating expenses:
Research and development		107,757		93,455		82,359
Selling, general and administrative		133,542		113,803		97,257
Litigation expense		2,464		1,922		1,243
Total operating expenses		243,763		209,180		180,859
Income from operations		102,562		113,488		77,424
Interest and other income, net		10,558		4,994		5,520
Income before income taxes		113,120		118,482		82,944
Income tax expense		4,281		13,214		17,741
Net income	$	108,839	$	105,268	$	65,203
Net income per share:
Basic	$	2.52	$	2.49	$	1.58
Diluted	$	2.38	$	2.36	$	1.50
Weighted-average shares outstanding:
Basic		43,165		42,247		41,350
Diluted		45,763		44,602		43,578

See accompanying notes to consolidated financial statements.

47

MONOLITHIC POWER SYSTEMS, INC.

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME

(in thousands) 

	Year Ended December 31,
	2019			2018			2017
Net income	$	108,839		$	105,268		$	65,203
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments		(1,706	)		(7,082	)		6,369
Change in unrealized gain (loss) on available-for-sale securities, net of tax of $(203), $209 and $0, respectively		1,773			(274	)		(341	)
Other comprehensive income (loss), net of tax		67			(7,356	)		6,028
Comprehensive income	$	108,906		$	97,912		$	71,231

See accompanying notes to consolidated financial statements.

48

MONOLITHIC POWER SYSTEMS, INC.

CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ EQUITY

(in thousands, except per share amounts) 

								Accumulated
	Common Stock and							Other			Total
	Additional Paid-in Capital				Retained			Comprehensive			Stockholders’
	Shares		Amount		Earnings			Income (Loss)			Equity
Balance as of January 1, 2017		40,793	$	315,969	$	119,362		$	(4,215	)	$	431,116
Net income		-		-		65,203			-			65,203
Other comprehensive income		-		-		-			6,028			6,028
Dividends and dividend equivalents declared ($0.80 per share)		-		-		(35,816	)		-			(35,816	)
Common stock issued under the employee equity incentive plan		781		150		-			-			150
Common stock issued under the employee stock purchase plan		40		2,701		-			-			2,701
Stock-based compensation expense		-		52,625		-			-			52,625
Cumulative effect of a change in accounting principles		-		5,141		(5,141	)		-			-
Balance as of December 31, 2017		41,614		376,586		143,608			1,813			522,007
Net income		-		-		105,268			-			105,268
Other comprehensive loss		-		-		-			(7,356	)		(7,356	)
Dividends and dividend equivalents declared ($1.20 per share)		-		-		(54,527	)		-			(54,527	)
Common stock issued under the employee equity incentive plan		858		10,637		-			-			10,637
Common stock issued under the employee stock purchase plan		33		3,028		-			-			3,028
Stock-based compensation expense		-		60,657		-			-			60,657
Cumulative effect of a change in accounting principles		-		-		379			-			379
Balance as of December 31, 2018		42,505		450,908		194,728			(5,543	)		640,093
Net income		-		-		108,839			-			108,839
Other comprehensive income		-		-		-			67			67
Dividends and dividend equivalents declared ($1.60 per share)		-		-		(74,117	)		-			(74,117	)
Common stock issued under the employee equity incentive plan		1,083		16,650		-			-			16,650
Common stock issued under the employee stock purchase plan		28		3,277		-			-			3,277
Stock-based compensation expense		-		78,682		-			-			78,682
Balance as of December 31, 2019		43,616	$	549,517	$	229,450		$	(5,476	)	$	773,491

See accompanying notes to consolidated financial statements.

49

MONOLITHIC POWER SYSTEMS, INC.

CONSOLIDATED STATEMENTS OF CASH FLOWS

(in thousands)

	Year Ended December 31,
	2019			2018			2017
Cash flows from operating activities:
Net income	$	108,839		$	105,268		$	65,203
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization		14,867			12,311			16,101
(Gain) loss on disposal and sale of property and equipment, net		(259	)		22			(3	)
Amortization of premium on available-for-sale securities		729			1,353			1,976
(Gain) loss on deferred compensation plan investments		(3,806	)		255			(2,531	)
Deferred taxes, net		(577	)		(843	)		(15,238	)
Stock-based compensation expense		78,699			60,607			52,617
Changes in operating assets and liabilities:
Accounts receivable		2,512			(18,079	)		(3,785	)
Inventories		8,865			(37,060	)		(27,795	)
Other assets		(10,204	)		(1,075	)		1,603
Accounts payable		3,048			871			3,077
Accrued compensation and related benefits		7,496			3,806			2,397
Accrued liabilities		7,449			7,092			10,852
Income tax liabilities		(1,355	)		6,923			29,347
Net cash provided by operating activities		216,303			141,451			133,821
Cash flows from investing activities:
Purchases of property and equipment		(95,806	)		(22,526	)		(65,770	)
Acquisition of in-place leases		(981	)		-			-
Purchases of short-term investments		(212,562	)		(99,199	)		(140,531	)
Proceeds from maturities and sales of short-term investments		135,801			109,131			77,502
Proceeds from sales of long-term investments		250			2,000			-
Proceeds from sales of property and equipment		9,268			-			-
Contributions to deferred compensation plan, net		(3,082	)		(4,146	)		(5,261	)
Net cash used in investing activities		(167,112	)		(14,740	)		(134,060	)
Cash flows from financing activities:
Property and equipment purchased on extended payment terms		(683	)		(749	)		(250	)
Proceeds from common stock issued under the employee equity incentive plan		16,650			10,637			150
Proceeds from common stock issued under the employee stock purchase plan		3,277			3,028			2,701
Dividends and dividend equivalents paid		(67,294	)		(47,475	)		(33,926	)
Net cash used in financing activities		(48,050	)		(34,559	)		(31,325	)
Effect of change in exchange rates		(883	)		(2,208	)		1,625
Net increase (decrease) in cash, cash equivalents and restricted cash		258			89,944			(29,939	)
Cash, cash equivalents and restricted cash, beginning of period		172,818			82,874			112,813
Cash, cash equivalents and restricted cash, end of period	$	173,076		$	172,818		$	82,874
Supplemental disclosures for cash flow information:
Cash paid for taxes	$	10,700		$	7,134		$	3,619
Non-cash investing and financing activities:
Liability accrued for property and equipment purchases	$	7,803		$	1,737		$	3,061
Liability accrued for dividends and dividend equivalents	$	21,955		$	16,319		$	10,686

See accompanying notes to consolidated financial statements.

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MONOLITHIC POWER SYSTEMS, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

1.  SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

Business

Monolithic Power Systems, Inc. (the “Company”) was incorporated in the State of California on August 22, 1997. On November 17, 2004, the Company was reincorporated in the State of Delaware. MPS designs, develops and markets integrated power semiconductor solutions and power delivery architectures. MPS’s mission is to provide innovative power solutions in the computing and storage, automotive, industrial, communications and consumer markets.

Basis of Presentation

The consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. Intercompany accounts and transactions have been eliminated in consolidation.

Use of Estimates

The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America (“GAAP”) requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements, and reported amounts of revenue and expenses during the reporting period. Significant estimates and assumptions used in these consolidated financial statements primarily include those related to revenue recognition, inventory valuation, valuation of share-based awards, contingencies and income tax valuation allowances. Actual results could differ from those estimates. 

Certain Significant Risks and Uncertainties

Financial instruments which potentially subject the Company to concentrations of credit risk consist primarily of cash and cash equivalents, short-term and long-term investments and accounts receivable. The Company’s cash consists of checking and savings accounts. The Company’s cash equivalents include short-term, highly liquid investments purchased with remaining maturities at the date of purchase of three months or less. The Company’s short-term investments may consist of corporate debt securities, certificates of deposit, commercial paper and government agency bonds and treasuries, and the long-term investments consist of government-backed student loan auction-rate securities. The Company generally does not require its customers to provide collateral or other security to support accounts receivable. To manage credit risk, management performs ongoing credit evaluations of its customers’ financial condition, monitors payment performance, and, in some cases, requires standby letters of credit. The Company also requires payment in advance for certain customers prior to shipments of goods. 

The Company participates in the dynamic high technology industry and believes that changes in any of the following areas could have a material adverse effect on its future financial position, results of operations or cash flows: advances and trends in new technologies and industry standards; competitive pressures in the form of new products or price reductions on current products; changes in product mix; changes in the overall demand for products offered by the Company; changes in third-party manufacturers; changes in key suppliers; changes in certain strategic relationships or customer relationships; litigation or claims against the Company based on intellectual property, patent, product, regulatory or other factors; fluctuations in foreign currency exchange rates; risk associated with changes in government policies and regulations on trade restrictions and corporate taxes; availability of necessary components or sub-assemblies; availability of foundry capacity; ability to integrate acquired companies; and the Company’s ability to attract and retain employees necessary to support its growth.

Foreign Currency  

In general, the functional currency of the Company’s international subsidiaries is the local currency. The primary subsidiaries are located in China, Taiwan and Europe, which utilize the Renminbi, the New Taiwan Dollar and the Euro as their currencies, respectively. Accordingly, assets and liabilities of the foreign subsidiaries are translated using exchange rates in effect at the end of the period. Revenue and costs are translated using average exchange rates for the period. The resulting translation adjustments are presented as a separate component of accumulated other comprehensive loss in stockholders’ equity on the Consolidated Balance Sheets. In addition, the Company incurs foreign currency exchange gain or loss related to certain intercompany transactions between the U.S. and its foreign subsidiaries that are denominated in a currency other than the functional currency. In connection with the settlement and remeasurement of the balances, the Company recorded foreign currency exchange gain (loss) of $(0.3) million, $1.0 million and $(0.6) million for the years ended December 31, 2019, 2018 and 2017, respectively, which were reported in interest and other income, net, on the Consolidated Statements of Operations.

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Cash, Cash Equivalents and Investments 

The Company classifies all highly liquid investments with stated maturities of three months or less from date of purchase as cash equivalents. The Company may classify investments with maturities beyond one year as short-term based on the nature of the investments and their availability for use in current operations.

Cash equivalents are stated at cost, which approximates fair market value. The Company’s short-term and long-term debt investments are classified as available-for-sale securities and are stated at their fair market value, with unrealized gains and losses recorded in accumulated other comprehensive loss. Premiums and discounts on debt investments are generally amortized or accreted over the life of the related available-for-sale securities. Interest income is recognized when earned. The cost of investments sold is determined on a specific identification method.

The Company’s available-for-sale investments are subject to periodic impairment reviews. When a decline in the fair value of a debt security below its amortized cost is considered other-than-temporary, the Company records an impairment charge in interest and other income, net.

Fair Value of Financial Instruments

Fair value is defined as the price that would be received from selling an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. When determining the fair value, the Company considers the principal or most advantageous market in which the Company would transact, as well as assumptions that market participants would use when pricing the assets or liabilities. Fair value is estimated by applying the following hierarchy, which prioritizes the inputs used to measure fair value into three levels and bases the categorization within the hierarchy upon the lowest level of input that is available and significant to the fair value measurement:

● Level 1 - Observable inputs that reflect quoted prices (unadjusted) for identical assets or liabilities in active markets.

● Level 2 - Inputs that are based upon quoted prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are not active, and model-based valuation techniques for which all significant inputs are observable in the market or can be derived from observable market data.

● Level 3 - Significant unobservable inputs to the valuation methodology and typically reflect management’s estimates of assumptions that market participants would use in pricing the asset or liability.  

Inventories

Inventories are stated at the lower of standard cost (which approximates actual cost determined on a first-in first-out basis) and estimated net realizable value. The Company writes down excess and obsolete inventory based on its age and forecasted demand, which includes estimates taking into consideration the Company’s outlook on market and economic conditions, technology changes, new product introductions and changes in strategic direction. Actual demand may differ from forecasted demand, and such differences may have a material effect on recorded inventory values. When the Company records a write-down on inventory, it establishes a new, lower cost basis for that inventory, and subsequent changes in facts and circumstances will not result in the restoration or increase in that newly established cost basis.

Property and Equipment

Property and equipment are stated at cost. Depreciation commences when an asset is placed in service and available for its intended use. Depreciation is computed using the straight-line method over the estimated useful lives of the assets. Buildings and building improvements have estimated useful lives of 20 to 40 years. Leasehold improvements are amortized over the shorter of the estimated useful lives or the lease period. Production equipment and software have estimated useful lives of three to eight years. Transportation equipment has estimated useful lives of 5 to 20 years. Furniture and fixtures have estimated useful lives of three to five years. Land is not depreciated.

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Impairment of Long-Lived Assets

The Company evaluates its long-lived assets other than goodwill for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. An impairment loss would be recognized when the sum of the undiscounted future net cash flows expected to result from the use of the asset and its eventual disposition is less than its carrying amount. Such impairment loss would be measured as the difference between the carrying amount of the asset and its fair value based on the present value of estimated future cash flows. The Company did not record material impairments in any of the periods presented.

Goodwill

Goodwill represents the excess of the fair value of purchase consideration over the fair value of net tangible and identified intangible assets as of the date of acquisition. Goodwill is not amortized.

The Company tests goodwill for impairment at least annually in the fourth quarter of the year, or whenever events or changes in circumstances indicate that goodwill may be impaired. The Company has elected to first assess the qualitative factors to determine whether it is more likely than not that the fair value of the reporting unit is less than its carrying amount. If the Company determines that it is more likely than not that its fair value is less than the carrying amount, then a quantitative goodwill impairment test is performed to measure the impairment loss. No impairment of goodwill has been identified in any of the periods presented.  

Deferred Compensation Plan 

The Company has a non-qualified, unfunded deferred compensation plan, which provides certain key employees, including executive officers, with the ability to defer the receipt of compensation in order to accumulate funds for retirement on a tax deferred basis. The Company does not make contributions to the plan or guarantee returns on the investments. The Company is responsible for the plan’s administrative expenses. Participants’ deferrals and investment gains and losses remain as the Company’s liabilities and the underlying assets are subject to claims of general creditors.

The liabilities for compensation deferred under the plan are recorded at fair value in each reporting period. Changes in the fair value of the liabilities are included in operating expense on the Consolidated Statements of Operations. The Company manages the risk of changes in the fair value of the liabilities by electing to match the liabilities with investments in corporate-owned life insurance policies, mutual funds and money market funds that offset a substantial portion of the exposure. The investments are recorded at the cash surrender value of the corporate-owned life insurance policies, and at the fair value of the mutual funds and money market funds, which are classified as trading securities. Changes in the cash surrender value of the corporate-owned life insurance policies and the fair value of mutual fund and money market fund investments are included in interest and other income, net on the Consolidated Statements of Operations. The following table summarizes the deferred compensation plan balances on the Consolidated Balance Sheets (in thousands):

	December 31,
	2019		2018
Deferred compensation plan asset components:
Cash surrender value of corporate-owned life insurance policies	$	16,883	$	13,103
Fair value of mutual funds and money market funds		21,975		18,867
Total	$	38,858	$	31,970
Deferred compensation plan assets reported in:
Other long-term assets	$	38,858	$	31,970
Deferred compensation plan liabilities reported in:
Accrued compensation and related benefits (short-term)	$	425	$	447
Other long-term liabilities		39,665		32,283
Total	$	40,090	$	32,730

Revenue Recognition

The Company recognizes revenue when it transfers control of promised goods or services to its customers in an amount that reflects the consideration to which it expects to be entitled to in exchange for those goods or services. See Note 2 for further discussion.

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Research and Development

Costs incurred in research and development are expensed as incurred.

Warranty Reserve

The Company generally provides one to two-year warranties against defects in materials and workmanship and will either repair the products, provide replacements at no charge to customers or issue a refund. As they are considered assurance-type warranties, the Company does not account for them as separate performance obligations. Warranty reserve requirements are generally based on a specific assessment of the products sold with warranties when a customer asserts a claim for warranty or a product defect. See Note 13 for the changes in warranty reserves for the periods presented.

Leases

The Company determines if an arrangement is a lease at inception. Lease terms may include options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. Operating lease right-of-use (“ROU”) assets represent the Company’s right to use an underlying asset for the lease term and operating lease liabilities represent the Company’s obligation to make lease payments arising from the lease. Operating lease ROU assets and liabilities are recognized at the commencement date based on the present value of remaining lease payments over the lease term. ROU assets also include any initial direct costs incurred and prepaid lease payments, less lease incentives received. Because the implicit rate in each lease is not readily determinable, the Company uses its estimated incremental borrowing rate to determine the present value of the remaining lease payment. The Company recognizes operating lease costs on a straight-line basis over the lease term.

The Company does not record short-term leases with a term of 12 months or less at the commencement date on the Consolidated Balance Sheets. For lease arrangements that contain lease and non-lease components, the Company accounts for them as single lease components.

For lease arrangements where the Company is the lessor, the Company recognizes lease income from operating leases on a straight-line basis over the lease term.

Stock-Based Compensation

The Company measures the cost of employee services received in exchange for an award of equity instruments based on the grant-date fair value of the award. The fair value of RSUs with service conditions or performance conditions is based on the grant date stock price. The fair value of shares issued under the ESPP and RSUs with a purchase price feature is estimated using the Black-Scholes model. The fair value of RSUs with market conditions, as well as RSUs containing both market and performance conditions, is estimated using a Monte Carlo simulation model. 

Compensation expense related to awards with service conditions is recorded on a straight-line basis over the requisite service period. Compensation expense related to awards subject to market or performance conditions is recognized over the requisite service period for each separately vesting tranche. For awards with only market conditions, compensation expense is not reversed if the market conditions are not satisfied. For awards with performance conditions, as well as awards containing both market and performance conditions, the Company recognizes compensation expense when the performance goals are achieved, or when it becomes probable that the performance goals will be achieved. Management performs the probability assessment on a quarterly basis by reviewing external factors, such as macroeconomic conditions and the analog industry revenue forecasts, and internal factors, such as the Company’s business and operational objectives and revenue forecasts. Changes in the probability assessment of achievement of the performance conditions are accounted for in the period of change by recording a cumulative catch-up adjustment as if the new estimate had been applied since the service inception date. Any previously recognized compensation expense is reversed if the performance conditions are not expected to be satisfied as a result of management’s assessment.

The Company accounts for forfeitures of equity awards when they occur.

Accounting for Income Taxes 

The Company recognizes federal, state and foreign current tax liabilities or assets based on its estimate of taxes payable or refundable in the current fiscal year by tax jurisdiction. The Company also recognizes federal, state and foreign deferred tax assets or liabilities for its estimate of future tax effects attributable to temporary differences and carryforwards. The Company records a valuation allowance to reduce any deferred tax assets by the amount of any tax benefits that, based on available evidence and judgment, are not expected to be realized.

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The Company’s calculation of current and deferred tax assets and liabilities is based on certain estimates and judgments and involves dealing with uncertainties in the application of complex tax laws. The Company’s estimates of current and deferred tax assets and liabilities may change based, in part, on added certainty, finality or uncertainty to an anticipated outcome, changes in accounting or tax laws in the U.S. or foreign jurisdictions where the Company operates, or changes in other facts or circumstances. In addition, the Company recognizes liabilities for potential U.S. and foreign income tax for uncertain income tax positions taken on its tax returns if it has less than a 50% likelihood of being sustained. If the Company determines that payment of these amounts is unnecessary or if the recorded tax liability is less than its current assessment, the Company may be required to recognize an income tax benefit or additional income tax expense in its financial statements in the period such determination is made. The Company has calculated its uncertain tax positions which were attributable to certain estimates and judgments.

Litigation and Contingencies

The Company is a party to actions and proceedings in the ordinary course of business, including potential litigation regarding its stockholders and its intellectual property, challenges to the enforceability or validity of its intellectual property, claims that the Company’s products infringe on the intellectual property rights of others, and employment matters. The pending proceedings involve complex questions of fact and law and will require the expenditure of significant funds and the diversion of other resources to prosecute and defend. In addition, from time to time, the Company becomes aware that it is subject to other contingent liabilities. When this occurs, the Company will evaluate the appropriate accounting for the potential contingent liabilities to determine whether a contingent liability should be recorded. In making this determination, management may, depending on the nature of the matter, consult with internal and external legal counsel and technical experts. Based on the facts and circumstances in each matter, the Company uses its judgment to determine whether it is probable that a contingent loss has occurred and whether the amount of such loss can be estimated. If the Company determines a loss is probable and estimable, the Company records a contingent loss. In determining the amount of a contingent loss, the Company takes into account advice received from experts for each specific matter regarding the status of legal proceedings, settlement negotiations, prior case history and other factors. Should the judgments and estimates made by management need to be adjusted as additional information becomes available, the Company may need to record additional contingent losses. Alternatively, if the judgments and estimates made by management are adjusted, for example, if a particular contingent loss does not occur, the contingent loss recorded would be reversed.

Litigation expense recorded on the Consolidated Statements of Operations includes primarily patent infringement litigation and other business matters. The Company records litigation costs in the period in which they are incurred. Proceeds resulting from settlement of litigation or favorable judgments are recorded as a reduction against litigation expense.

Net Income per Share

Basic net income per share is computed by dividing net income by the weighted-average number of common shares outstanding for the period. Diluted net income per share reflects the potential dilution that would occur if outstanding securities or other contracts to issue common stock were exercised or converted into common shares, and calculated using the treasury stock method. Contingently issuable shares, including equity awards with performance conditions or market conditions, are considered outstanding common shares and included in the basic net income per share as of the date that all necessary conditions to earn the awards have been satisfied. Prior to the end of the contingency period, the number of contingently issuable shares included in the diluted net income per share is based on the number of shares, if any, that would be issuable under the terms of the arrangement at the end of the reporting period.

The Company’s RSUs contain forfeitable rights to receive cash dividend equivalents, which are accumulated and paid to the employees when the underlying RSUs vest. Dividend equivalents accumulated on the underlying RSUs are forfeited if the employees do not fulfill the requisite service requirement and, as a result, the awards do not vest. Accordingly, these awards are not treated as participating securities in the net income per share calculation. 

Comprehensive Income 

Comprehensive income represents the change in the Company’s net assets during the period from non-owner sources. Accumulated other comprehensive loss presented on the Consolidated Balance Sheets primarily consists of unrealized gains or losses related to available-for-sale investments and foreign currency translation adjustments.

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Recently Adopted Accounting Pronouncement

In  February 2016, the FASB issued Accounting Standards Update (“ASU”) No. 2016-02, Leases (Topic 842), which requires entities to recognize ROU assets and lease liabilities on the balance sheets for leases with terms greater than 12 months. In addition, the standard applies to leases embedded in service or other arrangements. The Company adopted the standard on  January 1, 2019 using the modified retrospective transition method and did not restate comparative periods, as permitted by the standard. In addition, the Company elected the transition practical expedients to not reassess whether its outstanding contracts as of December 31, 2018 contained or were leases, classification of its existing leases and lease terms.

Upon adoption, the Company recognized ROU assets and lease liabilities of its outstanding operating leases on the Consolidated Balance Sheets, primarily related to real estate. The adoption did not have a material impact on the Consolidated Statements of Operations or the Consolidated Statements of Cash Flows. See Note 7 for further discussion.

Recent Accounting Pronouncements Not Yet Adopted as of December 31, 2019

In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes, which eliminates certain exceptions related to the approach for intra-period tax allocation, the methodology for calculating income taxes in an interim period and the recognition of deferred tax liabilities for outside basis differences. The standard also clarifies and simplifies other aspects of the accounting for income taxes. The standard will be effective for annual reporting periods beginning after December 15, 2020. Early adoption is permitted. The standard will generally be applied prospectively, with certain exceptions. The Company is evaluating the impact of the adoption on its consolidated financial statements.

In  August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework — Changes to the Disclosure Requirements for Fair Value Measurement, which changes certain disclosure requirements, including those related to Level 3 fair value measurements. The standard will be effective for annual reporting periods beginning after  December 15, 2019. The Company does not expect the adoption of this standard to have a material impact on its disclosures.

In  January 2017, the FASB issued ASU No. 2017-04, Intangibles – Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment, which simplifies the accounting for goodwill impairment. The guidance removes step two of the goodwill impairment test, which requires a hypothetical purchase price allocation to measure the amount of a goodwill impairment. A goodwill impairment will now be the amount by which a reporting unit’s carrying value exceeds its fair value, not to exceed the carrying amount of goodwill. Entities will continue to have the option to perform a qualitative assessment to determine if a quantitative impairment test is necessary. The standard will be applied prospectively, and will be effective for annual reporting periods beginning after  December 15, 2019. The Company will continue to perform the qualitative assessment on its goodwill impairment test and does not expect the adoption of this standard to have a material impact.

In  June 2016, the FASB issued ASU No. 2016-13, Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, which introduces a model based on expected losses to estimate credit losses for financial assets held at amortized cost. In addition, for available-for-sale debt securities, the standard eliminates the concept of other-than-temporary impairment and entities will be required to recognize an allowance for credit losses rather than reductions in the amortized cost of the securities. The standard will be effective for annual reporting periods beginning after  December 15, 2019. Entities will apply the standard by recording a cumulative-effect adjustment to retained earnings. The effect of the standard on the Company’s available-for-sale debt securities will largely depend on the composition of the investment portfolio, the financial condition of the issuers, the credit quality and expected collectability of the securities, and economic conditions. The Company does not expect the standard to have a material impact on its consolidated financial statements at the time of adoption.

2. REVENUE RECOGNITION

The Company adopted ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606), on  January 1, 2018 using the modified retrospective transition method applied to those contracts which were not completed as of  December 31, 2017. Results for reporting periods beginning after  January 1, 2018 are presented under Topic 606, while prior-period amounts have not been retrospectively adjusted and were reported in accordance with Topic 605, Revenue Recognition.

Revenue from Product Sales

The Company generates revenue primarily from product sales, which include assembled and tested integrated circuits, as well as dies in wafer form. These product sales were 99%, 98% and 98% of the Company’s total revenue for the years ended December 31, 2019, 2018 and 2017, respectively. The remaining revenue primarily includes royalty revenue from licensing arrangements and revenue from wafer testing services performed for third parties, which have not been significant in all periods presented. See Note 16 for the disaggregation of the Company’s revenue by geographic regions and by product families.

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The Company sells its products primarily through third-party distributors, value-added resellers, OEMs, ODMs and EMS providers. For the years ended December 31, 2019, 2018 and 2017, 83%, 87% and 88%, respectively, of the Company’s product sales were made through distribution arrangements. These distribution arrangements contain enforceable rights and obligations specific to those distributors and not the end customers. Purchase orders, which are generally governed by sales agreements or the Company's standard terms of sale, set the final terms for unit price, quantity, shipping and payment agreed by both parties. The Company considers purchase orders to be the contracts with customers. The unit price as stated on the purchase orders is considered the observable, stand-alone selling price for the arrangements.

The Company recognizes revenue when it satisfies a performance obligation by transferring control of the promised goods or services to its customers, in an amount that reflects the consideration the Company expects to be entitled to in exchange for those goods or services. The Company excludes taxes assessed by government authorities, such as sales taxes, from revenue.

Product sales consist of a single performance obligation that the Company satisfies at a point in time. The Company recognizes product revenue from distributors and direct end customers when the following events have occurred: (a) the Company has transferred physical possession of the products, (b) the Company has a present right to payment, (c) the customer has legal title to the products, and (d) the customer bears significant risks and rewards of ownership of the products. In accordance with the shipping terms specified in the contracts, these criteria are generally met when the products are shipped from the Company’s facilities (such as the “Ex Works” shipping term) or delivered to the customers’ locations (such as the “Delivered Duty Paid” shipping term).

Under certain consignment agreements, revenue is not recognized when the products are shipped and delivered to be held at customers’ designated locations because the Company continues to control the products and retain ownership, and the customers do not have an unconditional obligation to pay. The Company recognizes revenue when the customers consume the products from the consigned inventory locations or, in some cases, after a 60-day period from the delivery date has passed, at which time control transfers to the customers and the Company invoices them for payment.

Variable Consideration

The Company accounts for price adjustment and stock rotation rights as variable consideration that reduces the transaction price, and recognizes that reduction in the same period the associated revenue is recognized. Three U.S.-based distributors have price adjustment rights when they sell the Company’s products to their end customers at a price that is lower than the distribution price invoiced by the Company. When the Company receives claims from the distributors that products have been sold to the end customers at the lower price, the Company issues the distributors credit memos for the price adjustments. The Company estimates the price adjustments using the expected value method based on an analysis of historical claims, at both the distributor and product level, as well as an assessment of any known trends of product sales mix. Other U.S. distributors and non-U.S. distributors, which make up the majority of the Company’s total sales to distributors, do not have price adjustment rights. The Company records a credit against accounts receivable for the estimated price adjustments, with a corresponding reduction to revenue.

Certain distributors have limited stock rotation rights that permit the return of a small percentage of the previous six months’ purchases in accordance with the contract terms. The Company estimates the stock rotation returns using the expected value method based on an analysis of historical returns, and the current level of inventory in the distribution channel. The Company records a liability for the stock rotation reserve, with a corresponding reduction to revenue. In addition, the Company recognizes an asset for product returns which represents the right to recover products from the customers related to stock rotations, with a corresponding reduction to cost of revenue.

Contract Balances

The Company records a receivable when it has an unconditional right to receive consideration after the performance obligations are satisfied. As of  December 31, 2019 and 2018, accounts receivable totaled $52.7 million and $55.2 million, respectively. The Company did not record any allowance for doubtful accounts as of  December 31, 2019 and 2018.

For certain customers located in Asia, the Company requires cash payments two weeks before the products are scheduled to be shipped to the customers. The Company records these payments received in advance of performance as customer prepayments within current accrued liabilities. As of  December 31, 2019 and 2018, customer prepayments totaled $3.4 million and $2.5 million, respectively. The increase in the customer prepayment balance for the year ended  December 31, 2019 resulted from an increase in unfulfilled customer orders for which the Company has received payments. For the year ended December 31, 2019, the Company recognized $2.5 million of revenue that was included in the customer prepayment balance as of  December 31, 2018.

Practical Expedients

The Company has elected the practical expedient to expense sales commissions as incurred because the amortization period would have been one year or less. 

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The Company’s standard payment terms generally require customers to pay 30 to 60 days after the Company satisfies the performance obligations. For those customers who are required to pay in advance, the Company satisfies the performance obligations generally within two weeks. The Company has elected not to determine whether contacts with customers contain significant financing components.

The Company’s unsatisfied performance obligations primarily include products held in consignment arrangements and customer purchase orders for products that the Company has not yet shipped. Because the Company expects to fulfill these performance obligations within one year, the Company has elected not to disclose the amount of these remaining performance obligations or the timing of recognition.

3.  CASH, CASH EQUIVALENTS, INVESTMENTS AND RESTRICTED CASH

The following is a summary of the Company’s cash, cash equivalents and investments (in thousands): 

	December 31,
	2019		2018
Cash, cash equivalents and investments:
Cash	$	144,860	$	131,569
Money market funds		28,100		41,135
Corporate debt securities		260,950		170,909
Commercial paper		1,994		-
U.S. treasuries and government agency bonds		19,493		32,068
Certificates of deposit		-		1,600
Auction-rate securities backed by student-loan notes		3,138		3,241
Total	$	458,535	$	380,522

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	December 31,
	2019		2018
Reported as:
Cash and cash equivalents	$	172,960	$	172,704
Short-term investments		282,437		204,577
Long-term investments		3,138		3,241
Total	$	458,535	$	380,522

The contractual maturities of the Company’s short-term and long-term available-for-sale investments are as follows (in thousands):

	December 31,
	2019		2018
Due in less than 1 year	$	147,532	$	125,845
Due in 1 - 5 years		134,905		78,732
Due in greater than 5 years		3,138		3,241
Total	$	285,575	$	207,818

The following tables summarize the unrealized gain and loss positions related to the Company’s available-for sale investments (in thousands): 

	December 31, 2019
	Amortized Cost		Unrealized Gains		Unrealized Losses			Total Fair Value		Fair Value of Investments in Unrealized Loss Position
Money market funds	$	28,100	$	-	$	-		$	28,100	$	-
Corporate debt securities		260,645		383		(78	)		260,950		93,262
Commercial paper		1,994		-		-			1,994		-
U.S. treasuries and government agency bonds		19,487		7		(1	)		19,493		993
Auction-rate securities backed by student-loan notes		3,320		-		(182	)		3,138		3,138
Total	$	313,546	$	390	$	(261	)	$	313,675	$	97,393

	December 31, 2018
	Amortized Cost		Unrealized Gains		Unrealized Losses			Total Fair Value		Fair Value of Investments in Unrealized Loss Position
Money market funds	$	41,135	$	-	$	-		$	41,135	$	-
Corporate debt securities		172,288		7		(1,386	)		170,909		166,204
U.S. treasuries and government agency bonds		32,207		2		(141	)		32,068		28,507
Certificates of deposit		1,600		-		-			1,600		-
Auction-rate securities backed by student-loan notes		3,570		-		(329	)		3,241		3,241
Total	$	250,800	$	9	$	(1,856	)	$	248,953	$	197,952

As of  December 31, 2019 and 2018, unrealized losses that had been in a continuous loss position for 12 months or longer were $0.2 million and $1.6 million, respectively. The Company typically invests in highly rated securities, with the primary objective of minimizing the potential risk of principal loss. The Company’s investment policy generally requires securities to be investment grade and limits the amount of credit exposure to any one issuer. When evaluating a debt security for other-than-temporary impairment, management reviewed factors such as the Company’s intent to sell, or whether it will more likely than not be required to sell, the security before recovery of its amortized cost basis, the extent to which the fair value of the security is less than its cost, the financial condition of the issuer and the credit quality of the investment. As of  December 31, 2019 and 2018, the Company did not consider any of its available-for-sale investments to be other-than-temporarily impaired.

The Company redeemed $0.3 million and $2.0 million of its auction-rate securities at face value for the years ended December 31, 2019 and 2018, respectively. There were no sales of auction-rate securities for the year ended December 31, 2017. The underlying maturities of the remaining auction-rate securities are up to 27 years. As of December 31, 2019 and 2018, the impairment of $0.2 million and $0.3 million, respectively, was determined to be temporary because management possessed both the intent and ability to hold these securities for a period of time sufficient to allow for any anticipated recovery in fair value. In addition, management believed that it was more likely than not that the Company would not have to sell these securities before recovery of its amortized cost basis. All scheduled interest payments have been received on time pursuant to the terms and conditions of the securities. To date, the Company has redeemed $40.0 million, or 92% of the original portfolio in these auction-rate securities, at par without any realized losses.

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Restricted Cash

The following table provides a reconciliation of cash, cash equivalents and restricted cash reported on the Consolidated Balance Sheets to the amounts reported on the Consolidated Statements of Cash Flows (in thousands): 

	December 31,
	2019		2018
Cash and cash equivalents	$	172,960	$	172,704
Restricted cash included in other long-term assets		116		114
Total cash, cash equivalents and restricted cash reported on the Consolidated Statements of Cash Flows	$	173,076	$	172,818

As of  December 31, 2019 and 2018, restricted cash included a security deposit that is set aside in a bank account and cannot be withdrawn by the Company under the terms of a lease agreement. The restriction will end upon the expiration of the lease.   

4. FAIR VALUE MEASUREMENTS

The following table details the fair value measurement of the financial assets (in thousands):

	December 31, 2019
	Total		Level 1		Level 2		Level 3
Money market funds	$	28,100	$	28,100	$	-	$	-
Corporate debt securities		260,950		-		260,950		-
Commercial paper		1,994		-		1,994		-
U.S. treasuries and government agency bonds		19,493		-		19,493		-
Auction-rate securities backed by student-loan notes		3,138		-		-		3,138
Mutual funds and money market funds under deferred compensation plan		21,975		21,975		-		-
Total	$	335,650	$	50,075	$	282,437	$	3,138

	December 31, 2018
	Total		Level 1		Level 2		Level 3
Money market funds	$	41,135	$	41,135	$	-	$	-
Corporate debt securities		170,909		-		170,909		-
U.S. treasuries and government agency bonds		32,068		-		32,068		-
Certificates of deposit		1,600		-		1,600		-
Auction-rate securities backed by student-loan notes		3,241		-		-		3,241
Mutual funds and money market funds under deferred compensation plan		18,867		18,867		-		-
Total	$	267,820	$	60,002	$	204,577	$	3,241

_______________

● Level 1—includes instruments with quoted prices in active markets for identical assets.

● Level 2—includes instruments for which the valuations are based upon quoted market prices in active markets involving similar assets or inputs other than quoted prices that are observable for the assets. The market inputs used to value these instruments generally consist of market yields, recently executed transactions, broker/dealer quotes or alternative pricing sources with reasonable levels of price transparency. Pricing sources  may include industry standard data providers, security master files from large financial institutions, and other third-party sources used to determine a daily market value.

● Level 3—includes instruments for which the valuations are based on inputs that are unobservable and significant to the overall fair value measurement.

The Company’s level 3 assets consist of government-backed student loan auction-rate securities. The following table provides a rollforward of the fair value of the auction-rate securities (in thousands): 

Balance at January 1, 2018	$	5,256
Change in unrealized loss included in other comprehensive income		(15	)
Sale and settlement at par		(2,000	)
Balance at December 31, 2018		3,241
Change in unrealized gain included in other comprehensive income		147
Sale and settlement at par		(250	)
Balance at December 31, 2019	$	3,138

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The Company determined the fair value of the auction-rate securities using a discounted cash flow model with the following assumptions:

	December 31,
	2019			2018
Time-to-liquidity (in years)	2	-	3	2	-	3
Discount rate	4.0%	-	8.3%	4.9%	-	10.1%

The fair value measurement involves the analysis of valuation techniques and evaluation of unobservable inputs commonly used by market participants to price similar instruments. Outputs from the valuation process are assessed against various market sources when they are available, including marketplace quotes, recent trades of similar illiquid securities and independent pricing services. The valuation of the auction-rate securities is subject to significant management judgment regarding projected future cash flows, which will depend on many factors, including the quality of the underlying collateral, estimated time to liquidity including potential to be called or restructured, underlying final maturity, insurance guaranty and market conditions, among others. Changes in any of the unobservable inputs used in the fair value measurement of auction-rate securities in isolation would result in a lower or higher fair value measurement. For example, an increase in the time-to-liquidity assumption or estimated discount rate would result in a lower fair value measurement.

5. BALANCE SHEET COMPONENTS

Inventories 

Inventories consist of the following (in thousands):

	December 31,
	2019		2018
Raw materials	$	22,872	$	43,017
Work in process		42,681		38,674
Finished goods		61,947		54,693
Total	$	127,500	$	136,384

Other Current Assets

Other current assets consist of the following (in thousands):

	December 31,
	2019		2018
RSU tax withholding proceeds receivable	$	6,106	$	39
Prepaid expense		7,991		3,425
Interest receivable		2,490		1,441
Assets for product returns		1,585		1,602
Prepaid wafer refund receivable		-		4,297
Other		1,433		1,127
Total	$	19,605	$	11,931

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Property and Equipment, Net

Property and equipment, net, consist of the following (in thousands):

	December 31,
	2019			2018
Production equipment and software	$	134,420		$	120,645
Buildings and improvements		149,443			100,135
Land		35,040			16,724
Transportation equipment		16,510			12,948
Leasehold improvements		7,173			4,755
Furniture and fixtures		4,660			4,341
Property and equipment		347,246			259,548
Less: accumulated depreciation and amortization		(118,931	)		(109,547	)
Property and equipment, net	$	228,315		$	150,001

Depreciation and amortization expense on property and equipment was $14.5 million, $11.4 million and $14.0 million for the years ended December 31, 2019, 2018 and 2017, respectively.

Other Long-Term Assets

Other long-term assets consist of the following (in thousands):

	December 31,
	2019		2018
Deferred compensation plan assets	$	38,858	$	31,970
Operating lease ROU assets		2,863		-
Prepaid expense		2,687		2,713
Other		1,544		1,296
Total	$	45,952	$	35,979

Accrued Liabilities

Accrued liabilities consist of the following (in thousands):

	December 31,
	2019		2018
Dividends and dividend equivalents	$	21,747	$	15,044
Stock rotation and sales returns		5,530		5,363
Customer prepayments		3,412		2,520
Income tax payable		2,435		7,018
Commissions		1,425		1,369
Operating lease liabilities		1,254		-
Warranty		1,139		4,564
Other		7,848		3,084
Total	$	44,790	$	38,962

Other Long-Term Liabilities

Other long-term liabilities consist of the following (in thousands):

	December 31,
	2019		2018
Deferred compensation plan liabilities	$	39,665	$	32,283
Dividend equivalents		6,265		6,145
Operating lease liabilities		1,103		-
Other		30		97
Total	$	47,063	$	38,525

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6. REAL ESTATE TRANSACTION

In  March 2019, the Company completed the purchase of an office building and land located in Kirkland, Washington for $52.9 million in cash. The property also had in-place leases for a portion of the building which were assumed by the Company. The Company accounted for the purchase as an asset acquisition and capitalized $0.4 million of transaction costs.

The purchase price allocation was as follows (in thousands):

Building	$	30,078
Land		22,254
In-place leases		981
Total	$	53,313

The fair value of the building was determined based on the income approach, which considered the discounted cash flows and direct capitalization analysis, and the sales comparison approach. The fair value of land was determined based on the sales comparison approach. The fair value of the in-place leases was determined primarily based on the analysis of the economic benefits of certain cost savings attributable to the leases.

The building is depreciated over a useful life of 40 years and the in-place leases are amortized over the average remaining lease terms of 3.5 years.

7. LEASES

 Lessee

The Company has operating leases primarily for administrative and sales and marketing offices, manufacturing operations and research and development facilities, employee housing units and certain equipment. These leases have remaining lease terms from less than a year to four years. Some of these leases include options to renew the lease term for up to five years or on a month-to-month basis. The Company does not have finance lease arrangements.

As of  December 31, 2019, operating lease ROU assets totaled $2.9 million and operating lease liabilities totaled $2.4 million. The following tables summarize certain information related to the leases (in thousands, except percentages):

	Year Ended
	December 31, 2019
Lease costs:
Operating lease costs	$	1,509
Short-term and other lease costs		465
Total lease costs	$	1,974

	Year Ended
	December 31, 2019
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$	1,364
ROU assets obtained in exchange for new operating lease liabilities (1)	$	3,667

	December 31, 2019
Weighted-average remaining lease term (in years)		2.1
Weighted-average discount rate		3.7	%

(1) The amount includes $2.3 million for operating leases existing on  January 1, 2019.

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As of  December 31, 2019, the maturities of the lease liabilities were as follows (in thousands):

2020	$	1,328
2021		734
2022		390
2023		22
Total remaining lease payments		2,474
Less: imputed interest		(117	)
Total lease liabilities	$	2,357
Reported as:
Current liabilities	$	1,254
Long-term liabilities	$	1,103

The Company has elected the transition option under Topic 842 and continued to apply the prior accounting standard for leases, including the disclosure requirements, in the comparative periods. As of December 31, 2018, future minimum rental payments under the non-cancelable operating leases were as follows (in thousands):

2019	$	1,511
2020		872
2021		273
2022		195
2023		26
Total	$	2,877

Rent expense for the years ended December 31, 2018 and 2017 was $1.8 million and $1.5 million, respectively.

Lessor

The Company owns certain office buildings and leases a portion of these properties to third parties under arrangements that are classified as operating leases. These leases have remaining lease terms from one year to five years. Some of these leases include options to renew the lease term for up to five years.

For the year ended  December 31, 2019, income related to lease payments was $1.8 million. As of  December 31, 2019, future income related to lease payments was as follows (in thousands):

2020	$	1,523
2021		1,378
2022		1,138
2023		604
2024		552
Thereafter		45
Total	$	5,240

8.  STOCK-BASED COMPENSATION

2014 Equity Incentive Plan (as amended, the “2014 Plan”)

The Board of Directors adopted the 2014 Plan in  April 2013, and the stockholders approved it in  June 2013. In  October 2014, the Board of Directors approved certain amendments to the 2014 Plan. The 2014 Plan, as amended, became effective on  November 13, 2014 and provides for the issuance of up to 5.5 million shares. The 2014 Plan will expire on  November 13, 2024. As of  December 31, 2019, 1.6 million shares remained available for future issuance under the 2014 Plan. 

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Stock-Based Compensation Expense

The Company recognized stock-based compensation expense as follows (in thousands):

	Year Ended December 31,
	2019		2018		2017
Cost of revenue	$	2,409	$	1,888	$	1,654
Research and development		19,584		15,990		14,816
Selling, general and administrative		56,706		42,729		36,147
Total stock-based compensation expense	$	78,699	$	60,607	$	52,617
Tax benefit related to stock-based compensation	$	2,754	$	4,383	$	5,054

RSUs

The Company’s RSUs include time-based RSUs, RSUs with performance conditions (“PSUs”), RSUs with market conditions (“MSUs”), and RSUs with both market and performance conditions (“MPSUs”). Vesting of awards with performance conditions or market conditions is subject to the achievement of pre-determined performance goals and the approval of such achievement by the Compensation Committee of the Board of Directors (the “Compensation Committee”). All awards include service conditions which require continued employment with the Company.

A summary of RSU activity is presented in the table below (in thousands, except per-share amounts):

	Time-Based RSUs					PSUs and MPSUs					MSUs					Total
	Number of Shares			Weighted-Average Grant Date Fair Value Per Share		Number of Shares			Weighted-Average Grant Date Fair Value Per Share		Number of Shares			Weighted-Average Grant Date Fair Value Per Share		Number of Shares			Weighted-Average Grant Date Fair Value Per Share
Outstanding at January 1, 2017		366		$	51.35		2,284		$	43.24		1,620		$	23.57		4,270		$	36.47
Granted		81		$	94.25		585	(1)	$	62.72		-		$	-		666		$	66.56
Vested		(175	)	$	48.35		(597	)	$	41.94		-		$	-		(772	)	$	43.39
Forfeited		(14	)	$	61.80		(6	)	$	49.82		-		$	-		(20	)	$	58.46
Outstanding at December 31, 2017		258		$	66.30		2,266		$	48.59		1,620		$	23.57		4,144		$	39.91
Granted		133		$	114.36		630	(1)	$	85.06		600		$	68.48		1,363		$	80.62
Vested		(136	)	$	60.23		(717	)	$	41.08		-		$	-		(853	)	$	44.13
Forfeited		(15	)	$	82.20		(5	)	$	63.16		(1	)	$	68.48		(21	)	$	76.92
Outstanding at December 31, 2018		240		$	95.38		2,174		$	61.61		2,219		$	35.69		4,633		$	50.94
Granted		52		$	141.32		512	(1)	$	99.88		-		$	-		564		$	103.68
Vested		(103	)	$	81.53		(656	)	$	53.72		(324	)	$	23.57		(1,083	)	$	47.34
Forfeited		(9	)	$	117.31		(43	)	$	42.72		(9	)	$	68.48		(61	)	$	57.01
Outstanding at December 31, 2019		180		$	115.45		1,987		$	74.50		1,886		$	37.63		4,053		$	59.16

(1) Amount reflects the number of awards that  may ultimately be earned based on management’s probability assessment of the achievement of performance conditions at each reporting period.

The intrinsic value related to vested RSUs was $138.3 million, $90.0 million and $74.0 million for the years ended December 31, 2019, 2018 and 2017, respectively. As of December 31, 2019, the total intrinsic value of all outstanding RSUs was $679.5 million, based on the closing stock price of $178.02. As of December 31, 2019, unamortized compensation expense related to all outstanding RSUs was $100.1 million with a weighted-average remaining recognition period of approximately three years. 

Cash proceeds from vested PSUs with a purchase price totaled $16.6 million and $10.6 million for the years ended  December 31, 2019 and 2018, respectively. There were no proceeds for the year ended December 31, 2017.

Time-Based RSUs

For the years ended December 31, 2019, 2018 and 2017, the Compensation Committee granted 52,000, 133,000, and 81,000 RSUs, respectively, with service conditions to non-executive employees and non-employee directors. The RSUs generally vest over four years for employees and one year for directors, subject to continued service with the Company.

PSUs and MPSUs

2019 PSUs:

In  February 2019, the Compensation Committee granted 151,000 PSUs to the executive officers, which represent a target number of shares to be earned based on the Company’s average two-year (2019 and 2020) revenue growth rate compared against the analog industry’s average two-year revenue growth rate as published by the Semiconductor Industry Association (“2019 Executive PSUs”). The maximum number of shares that an executive officer can earn is 300% of the target number of the 2019 Executive PSUs. 50% of the 2019 Executive PSUs will vest in the first quarter of 2021 if the pre-determined performance goals are met during the performance period. The remaining 2019 Executive PSUs will vest over the following two years on a quarterly basis. Assuming the achievement of the highest level of performance goals, the total stock-based compensation cost for the 2019 Executive PSUs is $46.6 million.

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The 2019 Executive PSUs contain a purchase price feature, which requires the employees to pay the Company $30 per share upon vesting of the shares. Shares that do not vest will not be subject to the purchase price payment. The Company determined the grant date fair value of the 2019 Executive PSUs using the Black-Scholes model with the following assumptions: stock price of $130.67, expected term of 2.6 years, expected volatility of 29.0% and risk-free interest rate of 2.5%.

In  October 2018, the Compensation Committee granted 53,000 PSUs to certain non-executive employees, which represent a target number of shares to be earned based on the Company’s 2020 revenue goals for certain regions or product line divisions, or based on the Company’s average two-year (2019 and 2020) revenue growth rate compared against the analog industry’s average two-year revenue growth rate as published by the Semiconductor Industry Association (“2019 Non-Executive PSUs”). The maximum number of shares that an employee can earn is either 200% or 300% of the target number of the 2019 Non-Executive PSUs, depending on the job classification of the employee. 50% of the 2019 Non-Executive PSUs will vest in the first quarter of 2021 if the pre-determined performance goals are met during the performance period. The remaining 2019 Non-Executive PSUs will vest over the following two years on an annual or quarterly basis. Assuming the achievement of the highest level of performance goals, the total stock-based compensation cost for the 2019 Non-Executive PSUs is $10.9 million.

The 2019 Non-Executive PSUs contain a purchase price feature, which requires the employees to pay the Company $30 per share upon vesting of the shares. Shares that do not vest will not be subject to the purchase price payment. The Company determined the grant date fair value of the 2019 Non-Executive PSUs using the Black-Scholes model with the following assumptions: stock price of $108.43, expected term of 2.9 years, expected volatility of 28.7% and risk-free interest rate of 2.9%. 

2018 PSUs:

In  February 2018, the Compensation Committee granted 188,000 PSUs to the executive officers, which represent a target number of shares to be earned based on the Company’s average two-year (2018 and 2019) revenue growth rate compared against the analog industry’s average two-year revenue growth rate as published by the Semiconductor Industry Association (“2018 Executive PSUs”). The maximum number of shares that an executive officer can earn is 300% of the target number of the 2018 Executive PSUs. 50% of the 2018 Executive PSUs will vest in the first quarter of 2020 if the pre-determined performance goals are met during the performance period. The remaining 2018 Executive PSUs will vest over the following two years on a quarterly basis. Assuming the achievement of the highest level of performance goals, the total stock-based compensation cost for the 2018 Executive PSUs is $46.1 million.

In  February 2018, the Compensation Committee granted 44,000 PSUs to certain non-executive employees, which represent a target number of shares to be earned based on the Company’s 2019 revenue goals for certain regions or product line divisions, or based on the Company’s average two-year (2018 and 2019) revenue growth rate compared against the analog industry’s average two-year revenue growth rate as published by the Semiconductor Industry Association (“2018 Non-Executive PSUs”). The maximum number of shares that an employee can earn is either 200% or 300% of the target number of the 2018 Non-Executive PSUs, depending on the job classification of the employee. 50% of the 2018 Non-Executive PSUs will vest in the first quarter of 2020 if the pre-determined performance goals are met during the performance period. The remaining 2018 Non-Executive PSUs will vest over the following two years on an annual or quarterly basis. Assuming the achievement of the highest level of performance goals, the total stock-based compensation cost for the 2018 Non-Executive PSUs, excluding cancelled shares for the terminated employees, is $8.8 million.

The 2018 Executive PSUs and the 2018 Non-Executive PSUs contain a purchase price feature, which requires the employees to pay the Company $30 per share upon vesting of the shares. Shares that do not vest will not be subject to the purchase price payment. The Company determined the grant date fair value of the 2018 Executive PSUs and the 2018 Non-Executive PSUs using the Black-Scholes model with the following assumptions: stock price of $110.00, expected term of 2.6 years, expected volatility of 27.5% and risk-free interest rate of 2.3%. 

2017 PSUs:

In February 2017, the Compensation Committee granted 200,000 PSUs to the executive officers, which represented a target number of shares that would be earned based on the Company’s average two-year (2017 and 2018) revenue growth rate compared against the analog industry’s average two-year revenue growth rate as published by the Semiconductor Industry Association (“2017 Executive PSUs”). The maximum number of shares that an executive officer could earn was 300% of the target number of the 2017 Executive PSUs. In  February 2019, the Compensation Committee approved the revenue achievement for the 2017 Executive PSUs and a total of 521,000 shares were awarded to the executive officers. 50% of the 2017 Executive PSUs vested in the first quarter of 2019. The remaining 2017 Executive PSUs vest over the following two years on a quarterly basis. Based on the actual achievement of the performance goals, the total stock-based compensation cost for the 2017 Executive PSUs is $31.5 million.

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In February 2017, the Compensation Committee granted 48,000 PSUs to certain non-executive employees, which represented a target number of shares that would be earned based on the Company’s 2018 revenue goals for certain regions or product line divisions, or based on the Company’s average two-year (2017 and 2018) revenue growth rate compared against the analog industry’s average two-year revenue growth rate as published by the Semiconductor Industry Association (“2017 Non-Executive PSUs”). The maximum number of shares that an employee could earn was either 200% or 300% of the target number of the 2017 Non-Executive PSUs, depending on the job classification of the employee. In  February 2019, the Compensation Committee approved the revenue achievement for the 2017 Non-Executive PSUs and a total of 101,000 shares were awarded to the employees. 50% of the 2017 Non-Executive PSUs vested in the first quarter of 2019. The remaining 2017 Non-Executive PSUs vest over the following two years on an annual or quarterly basis. Based on the actual achievement of the performance goals, the total stock-based compensation cost for the 2017 Non-Executive PSUs, excluding cancelled shares for the terminated employees, is $6.1 million.

The 2017 Executive PSUs and the 2017 Non-Executive PSUs contain a purchase price feature, which requires the employees to pay the Company $30 per share upon vesting of the shares. Shares that do not vest will not be subject to the purchase price payment. The Company determined the grant date fair value of the 2017 Executive PSUs and the 2017 Non-Executive PSUs using the Black-Scholes model with the following assumptions: stock price of $89.37, expected term of 2.6 years, expected volatility of 28.6% and risk-free interest rate of 1.3%. 

2015 MPSUs:

In December 2015, the Compensation Committee granted 86,000 MPSUs to the executive officers and 41,000 MPSUs to certain non-executive employees, which represented a target number of shares that would be earned upon achievement of both market conditions and performance conditions (“2015 MPSUs”). The maximum number of shares that an employee could earn was 500% of the target number of the 2015 MPSUs. The 2015 MPSUs consisted of four separate tranches with various performance periods all ended on  December 31, 2019. The first tranche contained market conditions only, which required the achievement of five stock price targets ranging from $71.36 to $95.57 with a performance period from  January 1, 2016 to  December 31, 2019. 

The second, third and fourth tranches contained both market and performance conditions. The five stock price targets for the second tranche ranged from $89.56 to $106.81 with a performance period from  January 1, 2017 to  December 31, 2019. The five stock price targets for the third tranche ranged from $120.80 to $135.48 with a performance period from  January 1, 2018 to  December 31, 2019. The five stock price targets for the fourth tranche ranged from $126.08 to $136.79 with a performance period from  January 1, 2019 to  December 31, 2019.

In addition, each of the second, third and fourth tranches required the achievement of one of following six operating metrics:

1.	Successful implementation of full digital solutions for certain power products.
2.	Successful implementation, and adoption by a key customer, of an integrated, software-based field-oriented control with sensors to motor drivers.
3.	Successful implementation of certain advanced power analog processes.
4.	Successful design wins and achievement of a specific level of revenue with a global networking customer.
5.	Achievement of a specific level of revenue with a global electronics manufacturer.
6.	Achievement of a specific level of market share with certain core power products.

The following table summarizes the achievement of the market and performance conditions:

Tranche	Market Conditions	Performance Conditions
One	All stock price targets were achieved as of September 30, 2017.	Not required.
Two	All stock price targets were achieved as of December 31, 2017.	Operating metric #1 was achieved as of December 31, 2018.
Three	All stock price targets were achieved as of September 30, 2018.	Operating metric #2 was achieved as of December 31, 2018.
Four	All stock price targets were achieved as of March 31, 2019.	Operating metric #3 was achieved as of September 30, 2019.

A total of 0.6 million shares were awarded to the employees. The 2015 MPSUs will vest on  January 1, 2020, with post-vesting sales restrictions on the vested shares for up to an additional two years.

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The Company determined the grant date fair value of the 2015 MPSUs using a Monte Carlo simulation model with the following weighted-average assumptions: stock price of $61.35, expected volatility of 33.2%, risk-free interest rate of 1.3%, and an illiquidity discount of 7.8% to account for the post-vesting sales restrictions. Based on the actual achievement of all of the market and performance goals, the total stock-based compensation cost for the 2015 MPSUs, excluding cancelled shares for the terminated employees, is $24.6 million ($8.3 million for the first tranche, $4.5 million for the second tranche, $5.2 million for the third tranche, and $6.6 million for the fourth tranche). 

MSUs

2018 MSUs:

In  October 2018, the Compensation Committee granted 60,000 MSUs to the executive officers and 60,000 MSUs to certain non-executive employees, which represented a target number of shares that would be earned upon achievement of stock price targets (“2018 MSUs”). The maximum number of shares that an employee could earn was 500% of the target number of the 2018 MSUs if the Company achieved five stock price targets ranging from $140 to $172 during a performance period from October 26, 2018 to December 31, 2023. As of December 31, 2019, all stock price targets have been achieved and the employees were awarded a total of 0.6 million shares. The 2018 MSUs will vest on  January 1, 2024, with post-vesting sales restrictions on the vested shares for up to an additional two years. The total stock-based compensation cost for the 2018 MSUs, excluding cancelled shares for the terminated employees, is $40.4 million.

The Company determined the grant date fair value of the 2018 MSUs using a Monte Carlo simulation model with the following assumptions: stock price of $108.43, expected volatility of 31.6%, a risk-free interest rate of 3.0%, and an illiquidity discount of 8.7% to account for the post-vesting sales restrictions. 

2013 MSUs:

In December 2013, the Compensation Committee granted 276,000 MSUs to the executive officers and 84,000 MSUs to certain non-executive employees, which represented a target number of shares that would be earned upon achievement of stock price targets (“2013 MSUs”). The maximum number of shares that an employee could earn was 500% of the target number of the 2013 MSUs if the Company achieved five price targets ranging from $40 to $56 during a performance period from January 1, 2014 to December 31, 2018. As of December 31, 2015, all stock price targets have been achieved and the employees were awarded a total of 1.8 million shares. The 2013 MSUs vest quarterly from January 1, 2019 to December 31, 2023. The total stock-based compensation cost for the 2013 MSUs, excluding cancelled shares for the terminated employees, is $38.2 million.

The Company determined the grant date fair value of the 2013 MSUs using a Monte Carlo simulation model with the following assumptions: stock price of $31.73, expected volatility of 38.7% and a risk-free interest rate of 1.6%. There was no illiquidity discount because the awards do not contain any post-vesting sales restrictions.

ESPP

Under the ESPP, eligible employees may purchase common stock through payroll deductions. Participants may not purchase more than 2,000 shares in a six-month offering period, or purchase shares having a value greater than $25,000 in any calendar year as measured at the beginning of the offering period in accordance with the Internal Revenue Code and applicable Treasury Regulations. The ESPP provides for an annual increase by an amount equal to the least of one million shares, 2% of the outstanding shares of common stock on the first day of the year, or a number of shares as determined by the Board of Directors. As of December 31, 2019, 4.5 million shares were available for future issuance. The ESPP will expire in November 2024.

For the years ended December 31, 2019, 2018 and 2017, 28,000, 33,000 and 40,000 shares, respectively, were issued. The intrinsic value of the shares issued was $0.7 million, $1.1 million and $1.0 million for the years ended December 31, 2019, 2018 and 2017, respectively. The unamortized expense was $0.1 million as of December 31, 2019, which will be recognized through the first quarter of 2020. The Black-Scholes model was used to value the employee stock purchase rights with the following weighted-average assumptions: 

	Year Ended December 31,
	2019			2018			2017
Expected term (in years)		0.5			0.5			0.5
Expected volatility		37.0	%		29.5	%		23.5	%
Risk-free interest rate		2.2	%		2.0	%		0.9	%
Dividend yield		1.1	%		1.0	%		0.9	%

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Cash proceeds from the shares issued under the ESPP were $3.3 million, $3.0 million and $2.7 million for the years ended December 31, 2019, 2018 and 2017, respectively.

9. DIVIDENDS AND DIVIDEND EQUIVALENTS

Cash Dividend Program

The Company has a dividend program approved by the Board of Directors, pursuant to which the Company intends to pay quarterly cash dividends on its common stock. Based on the Company’s historical practice, stockholders of record as of the last business day of the quarter are entitled to receive the quarterly cash dividends when and if declared by the Board of Directors, which are payable to the stockholders in the following month. The Board of Directors declared the following cash dividends (in thousands, except per-share amounts):   

	Year Ended December 31,
	2019		2018		2017
Dividend declared per share	$	1.60	$	1.20	$	0.80
Total amount	$	69,196	$	50,803	$	33,145

As of  December 31, 2019 and 2018, accrued dividends totaled $17.4 million and $12.8 million, respectively.

The declaration of any future cash dividends is at the discretion of the Board of Directors and will depend on, among other things, the Company’s financial condition, results of operations, capital requirements, business conditions, and other factors that the Board of Directors  may deem relevant, as well as a determination that cash dividends are in the best interests of the stockholders.

The Company anticipates that cash used for future dividend payments will come from its domestic cash, cash generated from ongoing U.S. operations, and cash repatriated from its Bermuda subsidiary. Earnings from other foreign subsidiaries will continue to be indefinitely reinvested.

Cash Dividend Equivalent Rights

The Company's RSUs contain rights to receive cash dividend equivalents, which entitle employees who hold RSUs to the same dividend value per share as holders of common stock. The dividend equivalents are accumulated and paid to the employees when the underlying RSUs vest. Dividend equivalents accumulated on the underlying RSUs are forfeited if the employees do not fulfill the requisite service requirement and, as a result, the awards do not vest. As of  December 31, 2019 and 2018, accrued dividend equivalents totaled $10.6 million and $8.4 million, respectively.   

10. INTEREST AND OTHER INCOME, NET

The components of interest and other income, net, are as follows (in thousands):

	Year Ended December 31,
	2019			2018			2017
Interest income	$	7,305		$	6,321		$	5,353
Amortization of premium on available-for-sale securities		(729	)		(1,353	)		(1,976	)
Gain (loss) on deferred compensation plan investments		3,806			(1,022	)		2,531
Foreign currency exchange gain (loss)		(310	)		953			(550	)
Other		486			95			162
Total	$	10,558		$	4,994		$	5,520

For the year ended December 31, 2019, “other” includes a $0.7 million gain recognized from the sale of a parcel of land, net of certain capitalized costs and selling expenses.

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11.   NET INCOME PER SHARE

The following table sets forth the computation of basic and diluted net income per share (in thousands, except per share amounts):

	Year Ended December 31,
	2019		2018		2017
Numerator:
Net income	$	108,839	$	105,268	$	65,203
Denominator:
Weighted-average outstanding shares - basic		43,165		42,247		41,350
Effect of dilutive securities		2,598		2,355		2,228
Weighted-average outstanding shares - diluted		45,763		44,602		43,578
Net income per share:
Basic	$	2.52	$	2.49	$	1.58
Diluted	$	2.38	$	2.36	$	1.50

Anti-dilutive common stock equivalents were not material in any of the periods presented.

12.  INCOME TAXES

The components of income before income taxes are as follows (in thousands):

	Year Ended December 31,
	2019			2018			2017
United States	$	(4,134	)	$	(13,151	)	$	(19,115	)
Foreign		117,254			131,633			102,059
Income before income taxes	$	113,120		$	118,482		$	82,944

The components of the income tax expense are as follows (in thousands):

	Year Ended December 31,
	2019			2018			2017
Current:
Federal	$	1,682		$	11,023		$	31,025
State		8			4			2
Foreign		3,105			2,992			1,967
Deferred:
Federal		(213	)		(797	)		(15,426	)
Foreign		(301	)		(8	)		173
Income tax expense	$	4,281		$	13,214		$	17,741

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The effective tax rate differs from the applicable U.S. statutory federal income tax rate as follows:

	Year Ended December 31,
	2019			2018			2017
U.S. statutory federal tax rate		21.0	%		21.0	%		35.0	%
Foreign income at lower rates		(20.7	)		(22.0	)		(41.2	)
Impact of the 2017 Tax Act:
Remeasurement of deferred taxes		-			-			11.8
One-time deemed repatriation transition tax		-			0.6			50.5
Global intangible low-taxed income (“GILTI”)		11.0			14.4			-
Changes in valuation allowance		2.1			-			(36.2	)
Stock-based compensation		(1.5	)		(1.1	)		2.2
Tax credits		(6.2	)		(1.9	)		(2.1	)
Other adjustments		(1.9	)		0.2			1.4
Effective tax rate		3.8	%		11.2	%		21.4	%

The components of net deferred tax assets consist of the following (in thousands):

	December 31,
	2019			2018
Deferred tax assets:
Tax credits	$	18,080		$	11,833
Stock-based compensation		6,237			10,040
Deferred compensation		7,110			6,829
Net operating losses		615			1,133
Other expenses not currently deductible		2,323			1,852
Deferred tax assets, gross		34,365			31,687
Valuation allowance		(15,411	)		(13,041	)
Deferred tax assets, net of valuation allowance		18,954			18,646
Deferred tax liabilities:
Depreciation and amortization		(1,259	)		(711	)
Undistributed foreign earnings		(77	)		(1,105	)
Other expenses currently deductible		(425	)		-
Deferred tax liabilities		(1,761	)		(1,816	)
Net deferred tax assets	$	17,193		$	16,830

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Deemed Repatriation Transition Tax:

As permitted by the 2017 Tax Act, the Company has elected to pay the one-time, deemed repatriation transition tax liability of $24.6 million in installments on an interest-free basis over eight years through 2025. For the years ended December 31, 2019 and 2018, the Company paid $1.3 million and $2.6 million of the transition tax, respectively. As of December 31, 2019 and 2018, $2.0 million and $1.3 million of the transition tax were recorded in current accrued liabilities, and $18.7 million and $20.7 million were recorded in long-term income tax liabilities, respectively.

GILTI:

The 2017 Tax Act subjects a U.S. parent shareholder to taxation of its GILTI, effective January 1, 2018. The GILTI inclusions impact companies that have foreign earnings generated without a large aggregate foreign fixed asset base and whose earnings are being taxed at a low tax rate. For the years ended December 31, 2019 and 2018, the Company included $58.6 million and $81.1 million, respectively, related to the GILTI provisions as additional Subpart F income, which was accounted for as a period cost.

Valuation Allowance:

The Company periodically evaluates its deferred tax assets, including a determination of whether a valuation allowance is necessary, based upon its ability to utilize the assets using a more likely than not analysis. The realizability of the Company’s net deferred tax assets is dependent on its ability to generate sufficient future taxable income during periods prior to the expiration of tax attributes to fully utilize these assets. As of December 31, 2019 and 2018, the Company has evaluated and concluded that no valuation allowance is required, except for a continued full valuation allowance on the deferred tax assets in California.

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Undistributed Earnings of Subsidiaries:

The Company has analyzed its global working capital and cash requirements, and has determined that it plans to repatriate cash from its Bermuda subsidiary on an ongoing basis to fund its future U.S.-based expenditures and dividends.  For the year ended December 31, 2019, the Company repatriated $75 million from its Bermuda subsidiary. As of December 31, 2019, the Company maintained an insignificant deferred tax liability related to California state taxes upon future repatriations.

For all other foreign subsidiaries, the Company expects to indefinitely reinvest undistributed earnings to fund their operations and research and development. As of December 31, 2019, the undistributed earnings were approximately $32.9 million. An actual repatriation of the undistributed earnings could be subject to additional foreign withholding taxes and U.S. state taxes. The Company expects to be able to take a 100% dividend received deduction to offset any U.S. federal income tax liability on the undistributed earnings. Determination of the unrecognized state and withholding deferred tax liability is not practicable at this time due to the complexities associated with the hypothetical calculation.

Other Income Tax Provision Matters

As of December 31, 2019, the Company did not have federal net operating loss carryforwards. As of December 31, 2019, the state net operating loss carryforwards for income tax purposes were $12.6 million, which will expire beginning in 2028.

As of December 31, 2019, the Company had no R&D tax credit carryforwards for federal income tax purposes, and $24.1 million for state income tax purposes, which can be carried forward indefinitely.

In the event of a change in ownership, as defined under federal and state tax laws, the Company's net operating loss and tax credit carryforwards could be subject to annual limitations. The annual limitations could result in the expiration of the net operating loss and tax credit carryforwards prior to utilization.

At December 31, 2019, the Company had $25.4 million of unrecognized tax benefits, $17.3 million of which would affect its effective tax rate if recognized after considering the valuation allowance. At December 31, 2018, the Company had $20.5 million of unrecognized tax benefits, $12.8 million of which would affect its effective tax rate if recognized after considering the valuation allowance.

A reconciliation of the gross unrecognized tax benefits is as follows (in thousands): 

Balance as of January 1, 2017	$	14,431
Increase for tax position of prior year		169
Increase for tax position of current year		2,360
Decrease due to lapse of statute of limitation		(688	)
Balance as of December 31, 2017		16,272
Increase for tax position of prior year		1,474
Increase for tax position of current year		2,957
Decrease due to lapse of statute of limitation		(212	)
Balance as of December 31, 2018		20,491
Increase for tax position of prior year		1,589
Increase for tax position of current year		4,663
Decrease due to settlement with tax authorities		(560	)
Decrease due to lapse of statute of limitation		(776	)
Balance as of December 31, 2019	$	25,407

The Company recognizes interest and penalties, if any, related to uncertain tax positions in its income tax provision. As of December 31, 2019 and 2018, the Company has $1.6 million and $0.9 million, respectively, of accrued interest related to uncertain tax positions, which were recorded in long-term income tax liabilities in the Consolidated Balance Sheets.

Uncertain tax positions relate to the allocation of income and deductions among the Company’s global entities and to the determination of the research and development tax credit. Various events, some of which cannot be predicted, such as clarification of tax law by administrative or judicial means, may occur and would require the Company to increase or decrease its reserves and effective income tax rate over the next twelve months. However, it is not possible to determine either the magnitude or the range of increases or decreases at this time.

The Company currently has reduced tax rates in its subsidiaries in Chengdu and Hangzhou, China through 2020 and 2021, respectively, for performing research and development activities.

In  July 2015, the U.S. Tax Court issued an opinion in Altera Corp. v. Commissioner, invalidating the Treasury regulations that require participants in qualified intercompany cost-sharing arrangements to share stock-based compensation costs. A final decision was issued by the Tax Court in  December 2015, and the IRS appealed the decision in  June 2016. In  June 2019, the Ninth Circuit Court of Appeals upheld the cost-sharing regulations. In  July 2019, Altera filed a petition for rehearing en banc in the Ninth Circuit Court of Appeals. In November 2019, the Ninth Circuit Court of Appeals declined to rehear the case. As of  December 31, 2019, it has not been determined if this ruling will be appealed. Due to the uncertainty surrounding the status of the current regulations, the Company has not recorded any adjustments as of  December 31, 2019. The Company will continue to monitor and evaluate the impact of any new developments on its financial statements. 

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Income Tax Examination

The Company is subject to examination of its income tax returns by the IRS and other tax authorities. In general, the tax years for 2007 and forward are open for examination for U.S. federal and state income tax purposes. The Company is currently not under any significant tax examinations in any jurisdictions.

13.  COMMITMENTS AND CONTINGENCIES

Warranty and Indemnification Provisions

The changes in warranty reserves are as follows (in thousands):

	Year Ended December 31,
	2019			2018			2017
Balance at beginning of period	$	4,564		$	2,416		$	1,030
Warranty provision for product sales		891			6,586			1,912
Settlements made		(2,768	)		(1,402	)		(40	)
Unused warranty provision		(1,548	)		(3,036	)		(486	)
Balance at end of period	$	1,139		$	4,564		$	2,416

The Company provides indemnification agreements to certain direct or indirect customers. The Company agrees to reimburse these parties for any damages, costs and expenses incurred by them as a result of legal actions taken against them by third parties for infringing upon their intellectual property rights as a result of using the Company’s products and technologies. These indemnification provisions are varied in their scope and are subject to certain terms, conditions, limitations and exclusions. In addition, the Company has entered into indemnification agreements with its directors and officers.

It is not possible to predict the maximum potential amount of future payments under these agreements due to the limited history of indemnification claims and the unique facts and circumstances involved in each particular agreement. There were no indemnification liabilities incurred in any of the periods presented. However, there can be no assurances that the Company will not incur any financial liabilities in the future as a result of these obligations.

Purchase Commitments

The Company has outstanding purchase commitments with its suppliers and other parties that require the future purchases of goods or services, which primarily consist of wafer and other inventory purchases, assembly and other manufacturing services, construction or purchases of property and equipment, and license arrangements. As of  December 31, 2019, the Company’s outstanding purchase obligations totaled approximately $90.6 million.

Litigation

The Company is a party to actions and proceedings in the ordinary course of business, including potential litigation initiated by its stockholders, challenges to the enforceability or validity of its intellectual property, claims that the Company’s products infringe on the intellectual property rights of others, and employment matters. These proceedings often involve complex questions of fact and law and  may require the expenditure of significant funds and the diversion of other resources to prosecute and defend. The Company defends itself vigorously against any such claims. As of  December 31, 2019, there were no material pending legal proceedings to which the Company was a party.

14.  EMPLOYEE 401(k) PLAN

The Company sponsors a 401(k) retirement savings plan for all employees in the U.S. who meet certain eligibility requirements. Participants may contribute up to the amount allowable as a deduction for federal income tax purposes. The Company is not required to contribute and did not contribute to the plan for the years ended December 31, 2019, 2018 and 2017.

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15.  SIGNIFICANT CUSTOMERS

The Company sells its products primarily through third-party distributors and value-added resellers, and directly to OEMs, ODMs and EMS providers. The following table summarizes those customers with sales equal to 10% or more of the Company's total revenue, or with accounts receivable balances equal to 10% or more of the Company’s total accounts receivable: 

	Revenue									Accounts Receivable
	Year Ended December 31,									December 31,
Customer	2019			2018			2017			2019			2018
Company A (distributor)		23	%		22	%		17	%		24	%		25	%
Company B (distributor)		*			10	%		*			11	%		16	%
Company C (distributor)		*			*			10	%		*			*
Company A (value-added reseller)		*			*			*			13	%		*

* Represents less than 10%.

The Company’s agreements with these third-party distributors and value-added reseller were made in the ordinary course of business and  may be terminated with or without cause by these customers with advance notice. Although the Company  may experience a short-term disruption in the distribution of its products and a short-term decline in revenue if its agreement with any of these customers was terminated, the Company believes that such termination would not have a material adverse effect on its financial statements because it would be able to engage alternative distributors, resellers and other distribution channels to deliver its products to end customers within a short period following the termination of the agreement with the customer.  

16.  SEGMENT AND GEOGRAPHIC INFORMATION 

The Company operates in one reportable segment that includes the design, development, marketing and sale of high-performance analog solutions for the computing and storage, automotive, industrial, communications and consumer markets. The Company’s chief operating decision maker is its Chief Executive Officer, who reviews financial information presented on a consolidated basis for purposes of allocating resources and evaluating financial performance. The Company derives a majority of its revenue from sales to customers located outside North America, with geographic revenue based on the customers’ ship-to locations.  

The following is a summary of revenue by geographic regions (in thousands):

	Year Ended December 31,
Country or Region	2019		2018		2017
China	$	382,740	$	334,726	$	257,787
Taiwan		73,801		75,307		83,357
Europe		49,467		49,484		38,140
Korea		43,900		41,238		34,155
Southeast Asia		32,031		36,495		25,755
Japan		27,812		26,853		20,187
United States		17,836		17,621		11,113
Other		334		658		435
Total	$	627,921	$	582,382	$	470,929

The following is a summary of revenue by major product families (in thousands):

	Year Ended December 31,
Product Family	2019		2018		2017
DC to DC	$	589,651	$	537,512	$	431,861
Lighting Control		38,270		44,870		39,068
Total	$	627,921	$	582,382	$	470,929

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The following is a summary of long-lived assets by geographic regions (in thousands): 

	December 31,
Country	2019		2018		2017
China	$	113,888	$	93,096	$	89,472
United States		94,671		39,054		37,539
Taiwan		17,652		16,972		17,238
Other		2,104		879		387
Total	$	228,315	$	150,001	$	144,636

In 2019, the Company revised this disclosure presentation to exclude certain non-current items primarily related to goodwill and deferred compensation assets in accordance with ASC 280, Segment Reporting.  Prior-year amounts have been corrected.  These changes did not impact the Consolidated Balance Sheets.

17. ACCUMULATED OTHER COMPREHENSIVE LOSS

The following table summarizes the changes in accumulated other comprehensive loss (in thousands):

	Unrealized Gains (Losses) on Available-for-Sale Securities			Foreign Currency Translation Adjustments			Total
Balance as of January 1, 2018	$	(1,364	)	$	3,177		$	1,813
Other comprehensive loss before reclassifications		(549	)		(7,082	)		(7,631	)
Amounts reclassified from accumulated other comprehensive income (loss)		66			-			66
Tax effect		209			-			209
Net current period other comprehensive loss		(274	)		(7,082	)		(7,356	)
Balance as of December 31, 2018		(1,638	)		(3,905	)		(5,543	)
Other comprehensive income (loss) before reclassifications		1,977			(1,706	)		271
Amounts reclassified from accumulated other comprehensive loss		(1	)		-			(1	)
Tax effect		(203	)		-			(203	)
Net current period other comprehensive income (loss)		1,773			(1,706	)		67
Balance as of December 31, 2019	$	135		$	(5,611	)	$	(5,476	)

The amounts reclassified from accumulated other comprehensive income (loss) were recorded in interest and other income, net, in the Consolidated Statements of Operations.  For the year ended December 31, 2019, the Company did not elect to reclassify the income tax effects of the 2017 Tax Act from accumulated other comprehensive loss to retained earnings as the amounts were not material.  

18. SUBSEQUENT EVENT

Cash Dividend Increase

In February 2020, the Company’s Board of Directors approved an increase in quarterly cash dividends from $0.40 per share to $0.50 per share.

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19. QUARTERLY FINANCIAL DATA (UNAUDITED)

	Three Months Ended
	December 31, 2019		September 30, 2019		June 30, 2019		March 31, 2019
	(in thousands, except per share amounts)
Revenue	$	166,738	$	168,813	$	151,007	$	141,363
Cost of revenue		74,802		75,655		67,782		63,357
Gross profit		91,936		93,158		83,225		78,006
Operating expenses:
Research and development		27,011		27,742		27,545		25,458
Selling, general and administrative		33,240		34,692		35,058		30,553
Litigation expense		991		692		503		278
Total operating expenses		61,242		63,126		63,106		56,289
Income from operations		30,694		30,032		20,119		21,717
Interest and other income, net		2,731		2,257		2,229		3,341
Income before income taxes		33,425		32,289		22,348		25,058
Income tax expense (benefit)		989		2,761		1,655		(1,123	)
Net income	$	32,436	$	29,528	$	20,693	$	26,181
Net income per share:
Basic	$	0.75	$	0.68	$	0.48	$	0.61
Diluted	$	0.70	$	0.64	$	0.45	$	0.58
Weighted-average shares outstanding:
Basic		43,496		43,308		43,109		42,749
Diluted		46,503		45,833		45,483		45,232

	Three Months Ended
	December 31, 2018			September 30, 2018		June 30, 2018		March 31, 2018
	(in thousands, except per share amounts)
Revenue	$	153,497		$	159,975	$	139,761	$	129,150
Cost of revenue		68,904			70,957		62,197		57,655
Gross profit		84,593			89,018		77,564		71,495
Operating expenses:
Research and development		22,735			25,630		23,481		21,609
Selling, general and administrative		28,372			29,552		28,561		27,318
Litigation expense		409			343		640		531
Total operating expenses		51,516			55,525		52,682		49,458
Income from operations		33,077			33,493		24,882		22,037
Interest and other income (expense), net		(393	)		2,714		2,232		440
Income before income taxes		32,684			36,207		27,114		22,477
Income tax expense		5,046			4,639		2,908		621
Net income	$	27,638		$	31,568	$	24,206	$	21,856
Net income per share:
Basic	$	0.65		$	0.75	$	0.57	$	0.52
Diluted	$	0.61		$	0.71	$	0.55	$	0.49
Weighted-average shares outstanding:
Basic		42,467			42,362		42,237		41,922
Diluted		45,058			44,669		44,400		44,282

77

ITEM 9.    CHANGES IN AND DISAGREEMENTS WITH ACCOUNTANTS ON ACCOUNTING AND FINANCIAL DISCLOSURE

None.

ITEM 9A. CONTROLS AND PROCEDURES

Evaluation of Disclosure Controls and Procedures

Our management, with the participation of our Chief Executive Officer and Chief Financial Officer, evaluated the effectiveness of our disclosure controls and procedures pursuant to Rule 13a-15(e) and Rule 15d-15(e) under the Securities Exchange Act of 1934 as of the end of the period covered by this Annual Report on Form 10-K. 

Based on this evaluation, our Chief Executive Officer and Chief Financial Officer concluded that, as of December 31, 2019, our disclosure controls and procedures are designed at a reasonable assurance level and are effective to provide reasonable assurance that information we are required to disclose in reports that we file or submit under the Exchange Act is recorded, processed, summarized, and reported within the time periods specified in the SEC’s rules and forms, and that such information is accumulated and communicated to our management, including our Chief Executive Officer and Chief Financial Officer, as appropriate, to allow timely decisions regarding required disclosure.

Management’s Report on Internal Control over Financial Reporting

Our management is responsible for establishing and maintaining adequate internal control over financial reporting. Our management conducted an evaluation of the effectiveness of our internal control over financial reporting based on the framework in Internal Control—Integrated Framework (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission. Based on this evaluation, management concluded that our internal control over financial reporting was effective as of December 31, 2019. Management reviewed the results of its assessment with our Audit Committee.

Our independent registered public accounting firm, Ernst & Young LLP, independently assessed the effectiveness of our internal control over financial reporting, as stated in the firm’s attestation report, which appears in Part II, Item 8 of this Annual Report on Form 10-K.

Changes in Internal Control over Financial Reporting

Effective January 1, 2019, we adopted ASU No. 2016-02, Leases (Topic 842). We have implemented additional business processes and control activities, primarily related to the analysis of lease contracts, recognition of the ROU assets and lease liabilities, and presentation and disclosure, in order to monitor and maintain appropriate controls over financial reporting. There were no other changes in our internal control over financial reporting that occurred during the quarter ended December 31, 2019, that have materially affected, or are reasonably likely to materially affect, our internal control over financial reporting.

Limitations on Effectiveness of Controls and Procedures

In designing and evaluating the disclosure controls and procedures, management recognizes that any controls and procedures, no matter how well designed and operated, can provide only reasonable assurance of achieving the desired control objectives. In addition, the design of disclosure controls and procedures must reflect the fact that there are resource constraints and that management is required to apply its judgment in evaluating the benefits of possible controls and procedures relative to their costs. 

ITEM 9B.   OTHER INFORMATION

None.

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PART III

ITEM 10.    DIRECTORS, EXECUTIVE OFFICERS AND CORPORATE GOVERNANCE

Reference is made to the information regarding directors and nominees, code of ethics, corporate governance matters and disclosure relating to compliance with Section 16(a) of the Securities Exchange Act of 1934 appearing under the captions “Election of Directors” and “Delinquent Section 16(a) Reports” in the Company’s Proxy Statement for its 2020 Annual Meeting of Stockholders (the “2020 Annual Meeting”), which information is incorporated in this Annual Report on Form 10-K by reference. Information regarding executive officers is set forth under the caption “Information about Executive Officers” in Part I of this Annual Report on Form 10-K.

ITEM 11.    EXECUTIVE COMPENSATION

The information required by this item will be set forth under the caption “Executive Officer Compensation” in the Company’s Proxy Statement for the 2020 Annual Meeting, and is incorporated herein by reference.

ITEM 12.    SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND MANAGEMENT AND RELATED STOCKHOLDER MATTERS

The information required by this item will be set forth under the captions “Security Ownership of Certain Beneficial Owners and Management” and “Equity Compensation Plan Information” in the Company’s Proxy Statement for the 2020 Annual Meeting, and is incorporated herein by reference.

ITEM 13.    CERTAIN RELATIONSHIPS AND RELATED TRANSACTIONS, AND DIRECTOR INDEPENDENCE

The information required by this item will be set forth under the captions “Certain Relationships and Related Transactions” and “Election of Directors” in the Company’s Proxy Statement for the 2020 Annual Meeting, and is incorporated herein by reference.

ITEM 14.    PRINCIPAL ACCOUNTING FEES AND SERVICES

The information required by this item will be set forth under the caption “Audit and Other Fees” in the Company’s Proxy Statement for the 2020 Annual Meeting, and is incorporated herein by reference.

79

PART IV

ITEM 15.    EXHIBITS, FINANCIAL STATEMENT SCHEDULES.

(a) Documents filed as part of this report

(1) All financial statements

Reports of Independent Registered Public Accounting Firms

Consolidated Balance Sheets

Consolidated Statements of Operations

Consolidated Statements of Comprehensive Income

Consolidated Statements of Stockholders’ Equity

Consolidated Statements of Cash Flows

Notes to Consolidated Financial Statements

(2) Financial Statement Schedules

All schedules have been omitted because the required information is not present or not present in amounts sufficient to require submission of the schedules, or because the information required is included in the consolidated financial statements or notes thereto.

(3) Exhibits

Exhibit Number	Description
3.1 (1)	Amended and Restated Certificate of Incorporation.
3.2 (2)	Amended and Restated Bylaws.
4.1	Description of the Registrant's Securities Registered Pursuant to Section 12 of the Securities Exchange Act of 1934.
10.1+ (3)	Registrant’s 2004 Employee Stock Purchase Plan and form of subscription agreement.
10.2+ (4)	Form of Directors’ and Officers’ Indemnification Agreement.
10.3+ (5)	Employment Agreement with Michael Hsing, and Amendment thereof.
10.4+ (6)	Employment Agreement with Maurice Sciammas, and Amendment thereof.
10.5+ (7)	Employment Agreement with Jim Moyer.
10.6+(8)	Employment Agreement with Deming Xiao, and Amendment thereof.
10.7+(9)	Letter Agreement with Victor Lee.
10.8+(10)	Letter Agreement with Jeff Zhou.
10.9+(11)	Monolithic Power Systems, Inc. Master Cash Performance Bonus Plan.
10.10+(12)	Letter Agreement with Eugen Elmiger.
10.11+(13)	Monolithic Power Systems, Inc. 2004 Equity Incentive Plan, as Amended, and Form of Grant Agreement.
10.12+(14)	Monolithic Power Systems, Inc. 2014 Equity Incentive Plan, as Amended, and Form of Grant Agreement.

80

10.13+(15)	Employment Agreement with Bernie Blegen.
10.14+	Employment Agreements with Saria Tseng and Amendment thereof.
21.1	Subsidiaries of Monolithic Power Systems, Inc.
23.1	Consent of Independent Registered Public Accounting Firm (Ernst & Young LLP).
23.2	Consent of Independent Registered Public Accounting Firm (Deloitte & Touche LLP).
24.1	Power of Attorney (included on Signature page to this Form 10-K).
31.1	Certification of Chief Executive Officer pursuant to Securities Exchange Act Rules 13a-14(a) and 15d-14(a), as adopted pursuant to Section 302 of the Sarbanes-Oxley Act of 2002.
31.2	Certification of Chief Financial Officer pursuant to Securities Exchange Act Rules 13a-14(a) and 15d-14(a), as adopted pursuant to Section 302 of the Sarbanes-Oxley Act of 2002.
32.1*	Certification of Chief Executive Officer and Chief Financial Officer pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002.
101.INS	Inline XBRL Instance Document - the instance document does not appear in the Interactive Data File because its XBRL tags are embedded within the Inline XBRL document
101.SCH	Inline XBRL Taxonomy Extension Schema Document
101.CAL	Inline XBRL Taxonomy Extension Calculation Linkbase Document
101.DEF	Inline XBRL Taxonomy Extension Definition Linkbase Document
101.LAB	Inline XBRL Taxonomy Extension Label Linkbase Document
101.PRE	Inline XBRL Taxonomy Extension Presentation Linkbase Document
104	Cover Page Interactive Data File (formatted as Inline XBRL and contained in Exhibit 101)

+ Management contract or compensatory plan or arrangement.

* This exhibit shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934 or otherwise subject to the liabilities of that Section, nor shall it be deemed incorporated by reference in any filings under the Securities Act of 1933 or the Securities Exchange Act of 1934, whether made before or after the date hereof and irrespective of any general incorporation language in any filings.

(1) Incorporated by reference to Exhibit 3.2 of the Registrant’s Registration Statement on Form S-1/A (Registration No. 333-117327), filed with the Securities and Exchange Commission on November 15, 2004.

(2) Incorporated by reference to Exhibit 3.4 of the Registrant’s Registration Statement on Form S-1/A (Registration No. 333-117327), filed with the Securities and Exchange Commission on November 15, 2004.

(3) Incorporated by reference to Exhibit 10.3 of the Registrant’s Registration Statement on Form S-1/A (Registration No. 333-117327), filed with the Securities and Exchange Commission on November 15, 2004.

(4) Incorporated by reference to Exhibit 10.4 of the Registrant’s Registration Statement on Form S-1/A (Registration No. 333-117327), filed with the Securities and Exchange Commission on November 15, 2004.

(5) Incorporated by reference to Exhibit 10.7 of the Registrant’s annual report on Form 10-K (File No. 000-51026), filed with the Securities and Exchange Commission on March 11, 2008 and Exhibit 10.1 of the Registrant’s current report on Form 8-K (File No. 000-51026), filed with the Securities and Exchange Commission on December 19, 2008.

(6) Incorporated by reference to Exhibit 10.8 of the Registrant’s annual report on Form 10-K (File No. 000-51026), filed with the Securities and Exchange Commission on March 11, 2008 and Exhibit 10.3 of the Registrant’s current report on Form 8-K (File No. 000-51026), filed with the Securities and Exchange Commission on December 19, 2008.

(7) Incorporated by reference to Exhibit 10.9 of the Registrant’s Registration Statement on Form S-1 (Registration No. 333-117327), filed with the Securities and Exchange Commission on July 13, 2004.

(8) Incorporated by reference to Exhibit 10.10 of the Registrant’s annual report on Form 10-K (File No. 000-51026), filed with the Securities and Exchange Commission on March 11, 2008 and Exhibit 10.4 of the Registrant’s current report on Form 8-K (File No. 000-51026), filed with the Securities and Exchange Commission on December 19, 2008.

81

 (9) Incorporated by reference to Exhibit 10.1 of the Registrant’s current report on Form 8-K (File No. 000-51026), filed with the Securities and Exchange Commission on September 14, 2006.

(10) Incorporated by reference to Exhibit 10.1 of the Registrant’s current report on Form 8-K (File No. 000-51026), filed with the Securities and Exchange Commission on February 3, 2010.

(11)	Incorporated by reference to Annexure C of the Registrant’s Proxy Statement on Schedule 14A (File No. 000-51026), filed with the Securities and Exchange Commission on April 30, 2013.
(12)	Incorporated by reference to Exhibit 10.36 of the Registrant’s annual report on Form 10-K (File No. 000-51026), filed with the Securities and Exchange Commission on March 10, 2014.
(13)	Incorporated by reference to Exhibit 4.4 of the Registrant’s Registration Statement on Form S-8 (Registration No. 333-199782), filed with the Securities and Exchange Commission on November 3, 2014.
(14)	Incorporated by reference to Exhibit 4.6 of the Registrant’s Registration Statement on Form S-8 (Registration No. 333-199782), filed with the Securities and Exchange Commission on November 3, 2014.
(15)	Incorporated by reference to Exhibit 10.1 of the Registrant’s current report on Form 8-K (File No. 000-51026), filed with the Securities and Exchange Commission on July 22, 2016.

ITEM 16.    FORM 10-K SUMMARY.

None.

82

SIGNATURES

Pursuant to the requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

	MONOLITHIC POWER SYSTEMS, INC.
Date: February 28, 2020	By:	/s/ Michael Hsing
		Michael Hsing
		President and Chief Executive Officer

POWER OF ATTORNEY

KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature appears below constitutes and appoints Michael Hsing and T. Bernie Blegen, jointly and severally, his attorneys-in-fact, each with the power of substitution, for him in any and all capacities, to sign any amendments to this report, and to file the same, with exhibits thereto and other documents in connection therewith, with the Securities and Exchange Commission, hereby ratifying and confirming all that each of said attorneys-in-fact, or his substitute or substitutes, may do or cause to be done by virtue hereof.

Pursuant to the requirements of the Securities Exchange Act of 1934, this report has been signed below on February 28, 2020 by the following persons on behalf of the registrant and in the capacities indicated:

/s/ Michael Hsing	President, Chief Executive Officer, and Director (Principal Executive Officer)
Michael Hsing
/s/ T. Bernie Blegen	Chief Financial Officer (Principal Financial and Accounting Officer)
T. Bernie Blegen
/s/ HERBERT CHANG	Director
Herbert Chang
/s/ EUGEN ELMIGER	Director
Eugen Elmiger
/s/ VICTOR K. LEE	Director
Victor K. Lee
/s/ JAMES C. MOYER	Director
James C. Moyer
/s/ JEFF ZHOU	Director
Jeff Zhou

83

EX-4.1

Exhibit 4.1

DESCRIPTION OF THE REGISTRANT’S SECURITIES

REGISTERED PURSUANT TO SECTION 12 OF THE

SECURITIES EXCHANGE ACT OF 1934

As of February 28, 2020, Monolithic Power Systems, Inc. (the “Company”) has one class of securities registered under Section 12 of the Securities Exchange Act of 1934, as amended: common stock, par value $0.001 per share (the “common stock”).

The following summary description sets forth some of the general terms and provisions of the common stock. It is subject to and qualified in its entirety by reference to the provisions of the Company’s Amended and Restated Certificate of Incorporation (the “Certificate of Incorporation”) and the Amended and Restated Bylaws (the “Bylaws”), which are filed as Exhibit 3.1 and Exhibit 3.2, respectively, to the Annual Report on Form 10-K, and applicable provisions of the Delaware General Corporation Law. The Company encourages you to read the Certificate of Incorporation, the Bylaws and the applicable provisions of the Delaware General Corporation Law for additional information.

General

Under the Certificate of Incorporation, the Company is authorized to issue up to 150,000,000 shares of common stock with a par value of $0.001 per share, and up to 5,000,000 shares of preferred stock with a par value of $0.001 per shares (the “preferred stock”). The shares of common stock currently outstanding are fully paid and non-assessable.  Currently, no shares of preferred stock are outstanding. The board of directors has the authority to adopt, amend or repeal the Bylaws, subject to certain limitations set forth in the Bylaws.

Voting Rights

The holders of shares of common stock are entitled to one vote per share in all elections of directors and on all other matters submitted to a vote of stockholders of the Company. The holders of shares of common stock do not have cumulative voting rights.

Dividend Rights

Subject to the preferences applicable to any outstanding shares of preferred stock, the holders of common stock are entitled to receive dividends, if any, as and when declared, from time to time, by the board of directors out of funds legally available therefor. Dividends may be paid in cash, in property or in shares of common stock.

No Preemptive, Conversion or Redemption Rights

The holders of shares of common stock have no preemptive rights and no right to convert their common stock into other securities. There are no redemption or sinking fund provisions applicable to the common stock.

Liquidation, Dissolution or Similar Rights

Upon liquidation, dissolution or winding up of the affairs of the Company, the holders of shares of common stock will be entitled to participate equally and ratably in the remaining assets of the Company, after the payment of all debts and liabilities of the Company and preferences applicable to any outstanding shares of preferred stock.

Preferred Stock

The board of directors has the authority, without further action by the stockholders, to issue shares of preferred stock in one or more classes or series. The board of directors may designate the rights, preferences and privileges of each series, any or all of which may be greater than the rights of the common stock. Although the actual effect of any issuance of preferred stock will not be known until the board of directors determines the specific rights of the holders of shares of preferred stock, such issuance could potentially affect the voting power, dividend or other rights of the holders of shares of common stock and, under certain circumstances, delay, defer or prevent a change-in-control or other corporate takeover.

Anti-Takeover Effects of Delaware Law and the Certificate of Incorporation and Bylaws

Certain provisions of Delaware law and the Certificate of Incorporation and Bylaws contain provisions that could make the following transactions difficult: acquisition by means of a tender offer; acquisition by means of a proxy contest or otherwise; or removal of incumbent officers and directors. These provisions are summarized below.

Delaware Anti-Takeover Statute

The Company is subject to the provisions of Section 203 of the Delaware General Corporation Law regulating corporate takeovers. In general, Section 203 prohibits a publicly-held Delaware corporation from engaging, under certain circumstances, in a business combination with an interested stockholder for a period of three years following the date the person became an interested stockholder unless:

● prior to the date of the transaction, the board of directors of the corporation approved either the business combination or the transaction which resulted in the stockholder becoming an interested stockholder;

● upon completion of the transaction that resulted in the stockholder becoming an interested stockholder, the interested stockholder owned at least 85% of the voting stock of the corporation outstanding at the time the transaction commenced, excluding for purposes of determining the voting stock outstanding, but not for determining the outstanding voting stock owned by the interested stockholder, (1) shares owned by persons who are directors and also officers and (2) shares owned by employee stock plans in which employee participants do not have the right to determine confidentially whether shares held subject to the plan will be tendered in a tender or exchange offer; or

● at or subsequent to the date of the transaction, the business combination is approved by the board of directors of the corporation and authorized at an annual or special meeting of stockholders, and not by written consent, by the affirmative vote of at least two-thirds of the outstanding voting stock which is not owned by the interested stockholder.

Generally, a business combination includes a merger, asset or stock sale, or other transaction resulting in a financial benefit to the interested stockholder. An interested stockholder is a person who, together with affiliates and associates, owns or, within three years prior to the determination of interested stockholder status, did own 15% or more of a corporation’s outstanding voting stock.

Undesignated Preferred Stock

Under the Certificate of Incorporation, the board of directors is authorized to issue undesignated preferred Stock with voting or other rights or preferences that could render more difficult, or discourage an attempt, to obtain control of the Company by means of a merger, tender offer, proxy contest, or otherwise.

No Cumulative Voting

The Certificate of Incorporation and the Bylaws do not provide for cumulative voting.

Special Stockholder Meetings

The Bylaws provide that a special meeting of stockholders may only be called by a majority of the board of directors, by the Chairman of the board of directors, or by the Chief Executive Officer.

Advance Notification of Stockholder Nominations and Proposals

The Bylaws establish advance notice procedures with respect to stockholder proposals and the nomination of candidates for election as directors, other than nominations made by or at the direction of the board of directors. These procedures provide that notice of stockholder proposals must be timely given in writing to the Company’s corporate secretary prior to the meeting at which the action is to be taken.

Board Composition

The Certificate of Incorporation and the Bylaws divide the board of directors into three classes with staggered three-year terms. The authorized number of directors may be changed only by resolution of the board of directors. Any director may be removed from office by the stockholders only for cause. Vacancies on the board of directors may be filled by a majority of the board of directors then in office, although less than a quorum, or by a sole remaining director.

No Stockholder Action by Written Consent

The Certificate of Incorporation and the Bylaws provide that all stockholder actions are required to be taken by a vote of the stockholders at an annual or special meeting and that stockholders may not take any action by written consent in lieu of a meeting. 

Amendment of the Bylaws

The Bylaws may be amended by the affirmative vote of a majority of the board of directors, or by the affirmative vote of the holders of a majority of the voting power of the common stock issued and outstanding.

Listing

The Company’s common stock is listed on The NASDAQ Global Select Market under the trading symbol “MPWR.”

Transfer Agent

The transfer agent and registrar for the Company's common stock is Computershare Trust Company, N.A.

EX-10.14

Exhibit 10.14

MONOLITHIC POWER SYSTEMS, INC.

EMPLOYMENT AGREEMENT

This Employment Agreement (this “Agreement”) by and between Saria Tseng (the “Employee”, (“Vice Present and General Counsel”)) and Monolithic Power Systems, Inc. (the “Company”), is entered into as of December 16, 2008.

WHEREAS, the Company desires to continue to employ the Employee and the Employee desires to continue employment with the Company on the terms and conditions set forth below;

NOW, THEREFORE, the parties hereto agree as follows:

1. Certain Definitions. For purposes of this Agreement:

(a) “Cause” means (i) the Employee’s failure to perform the duties or responsibilities of the Employee’s employment, in any material respect, as reasonably required or directed by the Board of Directors of the Company (the “Board”) or the Chief Executive Officer (the “CEO”) or the Chief Legal Officer (the “CLO”), which failure is not cured within thirty (30) days following written notice to the Employee of the poor performance describing in reasonable detail the poor performance; (ii) the Employee personally engaging in illegal conduct that is detrimental to the Company; (iii) the Employee being convicted of or pleading nolo contendere to a felony or other crime involving moral turpitude; or (iv) the Employee committing a material act of dishonesty, fraud or misappropriation of property.

(b) “Change in Control” means the occurrence of (a) a change in the ownership of the Company, (b) a change in the effective control of the Company, or (c) a change in the ownership of a substantial portion of the assets of the Company, as such terms are defined in Treasury Regulation Section 409A-3(i)(5), but only to the extent that such change also constitutes one or more of the following events:

(i) Any “person” (as such term is used in Sections 13(d) and 14(d) of the Exchange Act) becomes the “beneficial owner” (as defined in Rule 13d-3 of the Exchange Act), directly or indirectly, of securities of the Company representing fifty percent (50%) or more of the total voting power represented by the Company’s then outstanding voting securities;

(ii) The consummation of the sale or disposition by the Company of all or substantially all of the Company’s assets;

(iii) A change in the composition of the Board occurring within a twelve (12) month period, as a result of which less than a majority of the directors are Incumbent Directors. “Incumbent Directors” means directors who either (A) are Directors as of the effective date of the Plan, or (B) are elected, or nominated for election, to the Board with the affirmative votes of at least a majority of the Incumbent Directors at the time of such election or nomination; or

(iv) The consummation of a merger or consolidation of the Company with any other corporation, other than a merger or consolidation which would result in the voting securities of the Company outstanding immediately prior thereto continuing to represent (either by remaining outstanding or by being converted into voting securities of the surviving entity or its parent) at least fifty (50%) of the total voting power represented by the voting securities of the Company or such surviving entity or its parent outstanding immediately after such merger or consolidation.

(c) “Disability” means the Employee is unable to engage in any substantial gainful activity by reason of any medically determinable physical or mental impairment that can be expected to result in death or can be expected to last for a continuous period of not less than twelve (12) months.

(d) “Good Reason” means, Employee’s termination of employment within ninety (90) days following the expiration of any cure period (as discussed below) following the occurrence of one or more of the following, without the Employee’s written consent, (i) a material reduction by the Company in the Employee’s base compensation as in effect immediately prior to such reduction, except where a substantially equivalent percentage reduction in base salary is applied to all other officers of the Company; (ii) a material, adverse reduction in the Employee’s authority, responsibilities or duties, as measured against the Employee’s authority, responsibilities or duties immediately prior to such change; or (iii) a material change in the geographic location at which the Employee must perform services (that is, the relocation of the Employee’s place of work to a facility or a location more than fifty (50) miles from the Employee’s then-present work location), but only if such relocation results in an increased one-way commute of at least fifty (50) miles based on the Employee’s primary residence at the time such relocation is announced. The Employee will not resign for Good Reason without first providing the Company with written notice within ninety (90) days of notice of the event that the Employee believes constitutes “Good Reason” specifically identifying the acts or omissions constituting the grounds for Good Reason and a reasonable cure period of not less than thirty (30) days following the date of such notice.

2. Employment and Duties. The Employee shall remain Vice President and General Counsel of the Company as of December 16, 2008 (“Effective Date”). The Employee shall report to the Sr. Vice President and CLO, and shall assume and discharge such responsibilities as are mutually agreed upon by the Employee and the CLO, and consistent with such office and position. The Employee shall perform faithfully the duties assigned to the Employee to the best of his or her ability.

3. Compensation.

(a) In consideration of the Employee’s services, the Employee shall be paid a base salary at the rate of $225,000.00 per year during the period of employment, as increased, if at all, pursuant to the following sentence (the “Base Salary”), to be paid in installments in accordance with the Company’s standard payroll practices. This Base Salary shall be reviewed for increases at least annually by the Company on the same basis and at the same time as the Company shall review the compensation of other executive officers of the Company including any review for the next fiscal year which has not yet occurred, but such increases are not guaranteed.

(b) Subject to approval by the Compensation Committee or Board, the Employee shall, from time to time, receive equity awards under the Company’s 2004 Stock Option Plan and such related grant agreements.

(c) The Employee shall participate in the Company bonus plan. The Employee will be entitled to receive an annual bonus equal to or exceeding twenty percent (20%) of the Employee’s annual base salary. The Employee’s annual target bonus will be payable on (i) achievement of personal and company specific performance objectives and (ii) the date established in writing by the Board, CEO or the Compensation Committee of the Board, subject to the Employee’s continued Company employment through such payment date, except as otherwise specifically provided in this Agreement.

4. At-Will Employment. The Company and the Employee acknowledge that the Employee’s employment is and shall continue at all times to be at-will, as defined under applicable law, meaning that either the Employee or the Company may terminate the Employee’s employment at any time and for any reason without any liability therefore, except as expressly provided in this Agreement. If the Employee’s employment terminates for any reason, the Employee shall not be entitled to any payments, benefits, damages, awards or compensation other than as provided by this Agreement, or as may otherwise be available in accordance with the Company’s established employee plans and policies at the time of termination.

5. Benefits. The Employee, together with the Employee’s spouse and dependent children, if any, shall be permitted, to the extent eligible, to participate at the Company’s expense in any group medical, dental, life insurance and disability insurance plans, or similar benefit plans of the Company that are available to other executive officers in each case pursuant to the terms and conditions of each such plan or program to the extent that the Company determines that participation on such terms and conditions would not result in unintended tax consequences. The Employee shall also be entitled to paid time off (PTO) annually in accordance with the Company’s policies or as otherwise agreed.

6. Termination for Cause and Voluntary Termination without Good Reason. In the event that the Employee resigns from the Company without Good Reason, or the Company terminates the Employee’s employment for Cause, the Employee shall not receive any compensation or benefits under this Agreement on account of, or after, such termination, except as required by applicable law. The Employee’s rights under any applicable Company benefit plans upon such termination shall be determined under the official terms of the respective benefit plans.

7. Termination without Cause and Voluntary Termination with Good Reason. Subject to Section 12 below, if (i) the Company terminates the Employee’s employment without Cause or the Employee resigns from the Company for Good Reason, then subject to Section 7(c), the Employee shall receive severance payments and partially-accelerated vesting of certain equity grants (together the “Severance Benefits”) pursuant to sub-sections 7(a) and (b) below.

(a) Severance Payments. After the date of such termination, the Company shall, for a period of six (6) months following the date of such termination, (i) continue to pay the Employee at a rate based on the Employee’s then-current Base Salary and target annual bonus, in installments in accordance with the Company’s standard payroll practices (as in effect immediately prior to such termination), and (ii) pay the Employee and the Employee’s dependents’ COBRA premiums under all Company-sponsored group health plans (other than the Company’s Flexible Spending Account) that such individuals are enrolled in at the time of such termination (unless the Company determines in its sole discretion that such payment of COBRA premiums could result in the imposition of any addition tax on the Employee, in which case the Company will instead reimburse the Employee for the cost of the Employee’s and the Employee’s dependents’ COBRA premiums, with such reimbursement to be made within thirty (30) days of the date such premiums are made). In the event such termination occurs within one (1) year following a Change of Control, then such payments and benefits shall continue for a period of six (6) months after the date of such termination. Notwithstanding the foregoing, however, (A) payments and benefits under clauses (i) and (ii) shall terminate immediately upon the date the Employee commences to provide services to another entity for compensation, whether present or deferred, and the Employee shall provide the Company with written notice of the Employee’s acceptance of such a service provider position within three (3) days thereof and (B) benefits under subsection (ii) shall cease on the date that the Employee (or the Employee’s dependents, as applicable) ceases to be eligible for COBRA continuation coverage under the normal COBRA rules.

(b) Vesting Acceleration. Effective on such termination, the Employee shall receive accelerated vesting equivalent to six (6) months of service beyond the date of Employee’s termination with respect to the shares subject to any grant of restricted stock or stock options (each, an “Equity Grant”) granted to the Employee, regardless of whether granted prior to, coincident with, or after, the Effective Date; provided, however, that in the event such termination occurs within one (1) year following a Change of Control, then fifty percent (50%) of the remaining shares subject to each such Equity Grant shall become vested in full and the period during which the Employee is permitted to exercise (if applicable) any such Equity Grant shall be extended until the earlier of (i) ten (10) years from the date of grant, or (ii) the expiration date of such Equity Grant (as of the date of grant).

(c) Section 409A.

(i) Notwithstanding anything to the contrary in this Agreement, no severance payable to the Employee, if any, pursuant to this Agreement, when considered together with any other severance payments or separation benefits that are considered deferred compensation under Section 409A of the Internal Revenue Code of 1986, as amended (the “Code”) and the final regulations and any guidance promulgated thereunder (“Section 409A”) (together, the “Deferred Compensation Separation Benefits”) will be payable until the Employee has a “separation from service” within the meaning of Section 409A.

(ii) Notwithstanding anything to the contrary in this Agreement, if the Employee is a “specified employee” within the meaning of Section 409A at the time of the Employee’s termination (other than due to death), then the Deferred Compensation Separation Benefits that are payable within the first six (6) months following the Employee’s separation from service, will become payable on the first payroll date that occurs on or after the date six (6) months and one (1) day following the date of the Employee’s separation from service. All subsequent Deferred Compensation Separation Benefits, if any, will be payable in accordance with the payment schedule applicable to each payment or benefit. Notwithstanding anything herein to the contrary, if the Employee dies following the Employee’s separation from service but prior to the six (6) month anniversary of the separation, then any payments delayed in accordance with this paragraph will be payable in a lump sum as soon as administratively practicable after the date of the Employee’s death and all other Deferred Compensation Separation Benefits will be payable in accordance with the payment schedule applicable to each payment or benefit. Each payment and benefit payable under this Agreement is intended to constitute separate payments for purposes of Section 1.409A-2(b)(2) of the Treasury Regulations.

(iii) Any amount paid under this Agreement that satisfies the requirements of the “short-term deferral” rule set forth in Section 1.409A-1(b)(4) of the Treasury Regulations will not constitute Deferred Compensation Separation Benefits for purposes of clause (i) above.

(iv) Any amount paid under this Agreement that qualifies as a payment made as a result of an involuntary separation from service pursuant to Section 1.409A-1(b)(9)(iii) of the Treasury Regulations that do not exceed the Section 409A Limit (as defined below) will not constitute Deferred Compensation Separation Benefits for purposes of clause (i) above.

(v) “Section 409A Limit” will mean the lesser of two (2) times: (A) the Employee’s annualized compensation based upon the annual rate of pay paid to the Employee during the Employee’s taxable year preceding the Employee’s taxable year of the Employee’s termination of employment as determined under, and with such adjustments as are set forth in, Treasury Regulation 1.409A-1(b)(9)(iii)(A)(1) and any Internal Revenue Service guidance issued with respect thereto, or (B) the maximum amount that may be taken into account under a qualified plan pursuant to Section 401(a)(17) of the Code for the year in which the Employee’s employment is terminated.

(vi) The foregoing provisions are intended to comply with the requirements of Section 409A so that none of the payments and benefits to be provided hereunder will be subject to the additional tax imposed under Section 409A, and any ambiguities herein will be interpreted to so comply. The Company and the Employee agree to work together in good faith to consider amendments to this Agreement and to take such reasonable actions which are necessary, appropriate or desirable to avoid imposition of any additional tax or income recognition prior to actual payment to the Employee under Section 409A.

8. Death. In the event of the Employee’s death, except as required by applicable law, the Company shall have no obligation to pay or provide any compensation or benefits under this Agreement. The Employee’s rights under the Company’s benefit plans in the event of the Employee’s death shall be determined under the official provisions of such benefit plans.

9. Disability. In the event of the Employee’s Disability, except as required by law, the Company may terminate the Employee’s employment and no compensation or benefits will be paid or provided to the Employee under this Agreement. The Employee’s rights under the Company’s benefit plans shall be determined under the official provisions of such benefit plans.

10. Other Activities. The Employee shall devote substantially all of the Employee’s working time and efforts to the business and affairs of the Company and its subsidiaries and to the diligent and faithful performance of the duties and responsibilities duly assigned to the Employee pursuant to this Agreement, except for vacations, holidays and sickness. However, to the extent that doing so does not materially interfere with the Employee’s obligations to the Company, the Employee may devote a reasonable amount of the Employee’s time to civic, community, or charitable activities and, with the prior written approval of the Company, serve as a director of other corporations and to other types of business or public activities not expressly mentioned in this paragraph, but only to the extent that such businesses or activities are not competitive with the Company’s actual or planned business activities.

11. Proprietary Information. During the period of employment and thereafter, the Employee shall not, without the prior written consent of the Company, disclose or use for any purpose (except in the course of the Employee’s employment under this Agreement and in furtherance of the business of the Company or any of its affiliates or subsidiaries) any confidential information or proprietary data of the Company or any of its affiliates or subsidiaries. The Employee agrees to execute the Company’s form of Proprietary Information Agreement, which is attached hereto as Exhibit A and incorporated herein by reference. The provisions of this Section 11 shall survive the termination of this Agreement and the Employee’s employment with the Company.

12. Covenant Not to Solicit. Beginning with the date of the Employee’s termination and until one (1) year thereafter, the Employee agrees that Employee will not:

(i) solicit any employee of the Company or any of its affiliates or subsidiaries for employment, or

(ii) interfere in any manner prohibited by applicable law with the contractual or employment relationship between the Company or any of its affiliates or subsidiaries and any employee of the Company or any of its affiliates or subsidiaries.

The provisions of this Section 12 shall survive the termination of this Agreement and the Employee’s employment with the Company.

13. Tax Provisions. In the event that the benefits provided for in the Agreement, when aggregated with any other payments or benefits received by the Employee, would (i) constitute “parachute payments” within the meaning of Section 280G of the Code, and (ii) would be subject to the excise tax imposed by Section 4999 of the Code (the “Excise Tax”), then the Employee’s benefits hereunder shall be either

(a) delivered in full, or

(b) delivered as to such lesser extent that would result in no portion of such benefits being subject to the Excise Tax, whichever of the foregoing amounts, taking into account the applicable federal, state and local income taxes and the Excise Tax, results in the receipt by the Employee on an after-tax basis, of the greatest amount of benefits, notwithstanding that all or some portion of such benefits may be taxable under Section 4999 of the Code.

Any reduction in payments and/or benefits required by this Section 13 shall occur in the following order: (1) reduction of vesting acceleration of equity awards; (2) reduction of cash payments; and (3) reduction of other benefits paid or provided to the Employee. In the event that acceleration of vesting of equity awards is to be reduced, such acceleration of vesting shall be cancelled in the reverse order of the date of grant for the Employee’s equity awards. If two or more equity awards are granted on the same date, each award will be reduced on a pro-rata basis. Unless the Company and the Employee otherwise agree in writing, any determination required under this paragraph shall be made in writing by the Company’s independent public accountants (the “Accountants”) whose determination shall be conclusive and binding upon the Employee and the Company for all purposes. For purposes of making the calculations required by this paragraph, the Accountants may make reasonable assumptions and approximations concerning applicable taxes and may rely on reasonable, good faith interpretations concerning the application of Sections 280G and 4999 of the Code. The Company and the Employee shall furnish to the Accountants such information and documents as the Accountants may reasonably request in order to make a determination under this paragraph. The provisions of this Section 14 shall survive the termination of this Agreement and the Employee’s employment with the Company.

14. Arbitration. Except as set forth in this Section 14, the Company and the Employee agree to resolve any disputes by binding arbitration. The Company and the Employee understand that this agreement to arbitrate covers all disputes that the Employee may have against the Company or its related entities or employees, including those that relate to the Employee’s employment or termination of employment (for example claims of unlawful discrimination or harassment). The arbitration will be conducted by an impartial arbitrator experienced in employment law (selected from the JAMS panel of arbitrators) in accordance with JAMS’ then-current employment arbitration rules (except as otherwise provided in this agreement). The Company and the Employee waive the right to institute a court action, except for requests for injunctive relief pending arbitration, and understand that they are giving up their right to a jury trial. The arbitrator’s award and opinion shall be in writing and in the form typically rendered in labor and employment arbitrations. The COMPANY will pay any filing fee and the fees and costs of the arbitrator, unless the Employee initiates the claim, in which case the Employee only will be required to contribute an amount equal to the filing fee for a claim initiated in a court of general jurisdiction in the California. Each of the Company and the Employee shall be responsible for their own attorneys’ fees and costs; however, the arbitrator may award attorneys’ fees to the prevailing party, if permitted by applicable law. This arbitration agreement does not prohibit either the Company or the Employee from filing a claim with an administrative agency (e.g., the EEOC), nor does it apply to claims for workers’ compensation or unemployment benefits, or claims for benefits under an employee welfare or pension plan that specifies a different dispute resolution procedure. The arbitration shall take place in Santa Clara County, California, unless the parties agree otherwise.

15. Former Employers. The Employee is not subject to any employment, confidentiality, or other agreement or restriction that would prevent the Employee from fully satisfying the Employee’s duties under this Agreement or that would be violated if the Employee did so. Without the Company’s prior written approval, the Employee promises that the Employee will not:

(a) disclose proprietary information belonging to a former employer or other entity without its written permission;

(b) contact any former employer’s customers or employees to solicit their business or employment on behalf of the Company or its affiliates; or

(c) distribute announcements about or otherwise publicize my employment with the Company or its affiliates.

The Employee will indemnify and hold the Company harmless from any liabilities, including defense costs, it may incur because the Employee is alleged to have broken any of these promises or improperly revealed or used such proprietary information or to have threatened to do so, or if a former employer challenges the Employee’s entering into this Agreement or rendering services pursuant to it.

16. Department of Homeland Security Verification Requirement. The Employee agrees to timely file all documents required by the Department of Homeland Security to verify the Employee’s identity and the Employee’s lawful employment in the United States. Notwithstanding any other provision of this Agreement, if the Employee fails to meet any such requirements promptly after receiving a written request from the Company to do so, the Employee agrees that the Employee’s employment shall terminate immediately and that the Employee shall not be entitled to any compensation or benefits from the Company of any type.

17. Governing Law. To the extent not governed by U.S. federal law, this Agreement shall be governed by and construed in accordance with the laws of the State of California applicable to agreements made and to be performed entirely within such state, without regard to principles of conflicts of laws.

18. Entire Agreement. This Agreement and all existing Equity Grants represent the entire agreement and understanding between the parties as to the subject matter hereof and thereof and supersede all prior or contemporaneous agreements as to the subject matter hereof and thereof, whether written or oral including, but not limited to, that certain Offer Letter between the Company and the Employee, dated October 15, 2004, which is hereby terminated and superseded in its entirety. No modification or amendment to this Agreement will be effective unless in writing signed by the party to be charged. Any subsequent change or changes in the Employee’s duties, salary or compensation will not affect the validity or scope of this Agreement. The Employee understands and agrees that the Company may, in its sole discretion, amend or terminate any Company-sponsored employee benefit plans.

19. Notices. Notices and all other communications contemplated by this Agreement shall be in writing and shall be deemed to have been duly given when personally delivered or when mailed by U.S. registered or certified mail, return receipt requested and postage prepaid. In the case of the Employee, mailed notices shall be addressed to him at the home address that he most recently communicated to the Company in writing. In the case of the Company, mailed notices shall be addressed to its corporate headquarters, and all notices shall be directed to the attention of its CEO.

20. Waiver etc. No waiver, alteration, or modification, if any, of the provisions of this Agreement shall be binding unless in writing and signed by duly authorized representatives of the parties hereto. If either party should waive any breach of any provisions of this Agreement, such party shall not thereby be deemed to have waived any preceding or succeeding breach of the same or any other provision of this Agreement.

21. Severability. If any term of this Agreement is held by a court of competent jurisdiction to be invalid, void or unenforceable, then the remainder of the terms of this Agreement shall remain in full force and effect and shall in no way be affected, impaired or invalidated.

22. Counterparts. This Agreement may be executed in counterparts, which together will constitute one instrument.

[THE REMAINDER OF THIS PAGE INTENTIONALLY LEFT BLANK.]

The parties have executed this Agreement as of the date first above written.

MONOLITHIC POWER SYSTEMS, INC.
By:	/s/ Michael Hsing
Name:	Michael Hsing
Title:	President and CEO
“Employee”
By:	/s/ Saria Tseng
Name:	Saria Tseng

MONOLITHIC POWER SYSTEMS, INC.

AMENDMENT TO EMPLOYMENT AGREEMENT

This Amendment to the Employment Agreement (the “Amendment”) is made as of February 9, 2010, by and between Monolithic Power Systems, Inc. (the “Company”), and Saria Tseng (the “Executive”).

RECITALS

WHEREAS, the Company and the Executive entered into that certain Employment Agreement dated December 16, 2008 (the “Agreement”).

WHEREAS, the Company and the Executive desire to amend the Agreement to (i) comply with the requirements of Section 409A of the Internal Revenue Code of 1986, as amended, and (ii) to make certain other changes in light of Executive’s new position and greater responsibilities as a Section 16 Officer of the Company.

NOW, THEREFORE, the Company and the Executive agree that in consideration of the foregoing and the promises and covenants contained herein, the parties agree as follows:

AGREEMENT

1. Executive. All references in the Agreement to “Employee” shall be deemed to amended to refer instead to “Executive”.

2. Cause. Section 1(a) of the Agreement is hereby amended to read in its entirety as follows:

““Cause” means (i) the Executive’s failure to perform the duties or responsibilities of the Executive’s employment, in any material respect, as reasonably required or directed by the Board of Directors of the Company (the “Board”) or the Chief Executive Officer (the “CEO”), which failure is not cured within thirty (30) days following written notice to the Executive of the poor performance describing in reasonable detail the poor performance; (ii) the Executive personally engaging in illegal conduct that is detrimental to the Company; (iii) the Executive being convicted of or pleading nolo contendere to a felony or other crime involving moral turpitude; or (iv) the Executive committing a material act of dishonesty, fraud or misappropriation of property.”

3. Employment and Duties. Section 2 of the Agreement, entitled “Employment and Duties,” is hereby amended to read in its entirety as follows:

“The Executive shall remain Vice President and General Counsel of the Company as of December 16, 2008 (“Effective Date”). The Executive shall report to the Chief Executive Officer (CEO), and shall assume and discharge such responsibilities as are mutually agreed upon by the Executive and the CEO, and consistent with such office and position. The Executive shall perform faithfully the duties assigned to the Executive to the best of his or her ability.”

4. Compensation. Sections 3 of the Agreement, entitled “Compensation,” is hereby amended to read in its entirety as follows:

“(a) In consideration of the Executive’s services, the Executive shall be paid a base salary at the rate of $260,000.00 per year during the period of employment, as increased, if at all, pursuant to the following sentence (the “Base Salary”), to be paid in installments in accordance with the Company’s standard payroll practices. This Base Salary shall be reviewed for increases at least annually by the Compensation Committee on the same basis and at the same time as the Compensation Committee shall review the compensation of other executive officers of the Company including any review for the next fiscal year which has not yet occurred, but such increases are not guaranteed.

(b) Subject to approval by the Compensation Committee or Board, the Executive shall, from time to time, receive equity awards under the Company’s Equity Incentive Plan and such related grant agreements.

(c) The Executive shall participate in the Company bonus plan. The Executive’s annual target bonus will be payable on (i) achievement of personal and company specific performance objectives and (ii) the date established in writing by the Board, CEO or the Compensation Committee of the Board, subject to the Executive’s continued Company employment through such payment date, except as otherwise specifically provided in this Agreement.”

5. Benefits. Section 5 of the Agreement, entitled “Benefits” is hereby amended to read in its entirety as follows:

“The Executive, together with the Executive’s spouse and dependent children, if any, shall be permitted, to the extent eligible, to participate at the Company’s expense in any group medical, dental, life insurance and disability insurance plans, or similar benefit plans of the Company that are available to other executive officers in each case pursuant to the terms and conditions of each such plan or program to the extent that the Company determines that participation on such terms and conditions would not result in unintended tax consequences. The Executive shall also be entitled to twenty (20) days of paid time off (PTO) or as otherwise agreed.”

6. Termination without Cause and Voluntary Termination with Good Reason. Section 7 of the Agreement, entitled “Termination without Cause and Voluntary Termination with Good Reason,” is hereby amended to read in its entirety as follows:

“7. Termination without Cause and Voluntary Termination with Good Reason. Subject to Section 12 below, if (i) the Company terminates the Executive’s employment without Cause or the Executive resigns from the Company for Good Reason, then subject to Section 7(c), the Executive shall receive severance payments and partially-accelerated vesting of certain equity grants (together the “Severance Benefits”) pursuant to sub-sections 7(a) and (b) below.

(a) Severance Payments. After the date of such termination, the Company shall, for a period of six (6) months following the date of such termination, (i) continue to pay the Executive at a rate based on the Executive’s then-current Base Salary and target annual bonus, in installments in accordance with the Company’s standard payroll practices (as in effect immediately prior to such termination), and (ii) pay the Executive and the Executive’s dependents’ COBRA premiums under all Company-sponsored group health plans (other than the Company’s Flexible Spending Account) that such individuals are enrolled in at the time of such termination (unless the Company determines in its sole discretion that such payment of COBRA premiums could result in the imposition of any additional tax on the Executive, in which case

the Company will instead reimburse the Executive for the cost of the Executive’s and the Executive’s dependents’ COBRA premiums, with such reimbursements to be made within thirty (30) days of the date such premiums are made). In the event such termination occurs within one (1) year following a Change of Control, then such payments and benefits shall continue for a period of one (1) year after the date of such termination. Notwithstanding the foregoing, however, (A) payments and benefits under clauses (i) and (ii) shall terminate immediately upon the date the Executive commences to provide services to another entity for compensation, whether present or deferred, and the Executive shall provide the Company with written notice of the Executive’s acceptance of such a service provider position within three (3) days thereof and (B) benefits under subsection (ii) shall cease on the date that the Executive (or the Executive’s dependents, as applicable) ceases to be eligible for COBRA continuation coverage under the normal COBRA rules.

(b) Vesting Acceleration. Effective on such termination, the Executive shall receive accelerated vesting equivalent to six (6) months of service beyond the date of Executive’s termination with respect to the shares subject to any grant of restricted stock or stock options (each, an “Equity Grant”) granted to the Executive, regardless of whether granted prior to, coincident with, or after, the Effective Date; provided, however, that in the event such termination occurs within one (1) year following a Change of Control, then one hundred percent (100%) of the remaining shares subject to each such Equity Grant shall become vested in full and the period during which the Executive is permitted to exercise (if applicable) any such Equity Grant shall be extended until the earlier of (i) ten (10) years from the date of grant, or (ii) the expiration date of such Equity Grant (as of the date of grant).

(c) Section 409A.

(i) Notwithstanding anything to the contrary in this Agreement, no severance payable to the Executive, if any, pursuant to this Agreement, when considered together with any other severance payments or separation benefits that are considered deferred compensation under Section 409A of the Internal Revenue Code of 1986, as amended (the “Code”) and the final regulations and any guidance promulgated thereunder (“Section 409A”) (together, the “Deferred Compensation Separation Benefits”) will be payable until the Executive has a “separation from service” within the meaning of Section 409A.

(ii) Notwithstanding anything to the contrary in this Agreement, if the Executive is a “specified employee” within the meaning of Section 409A at the time of the Executive’s termination (other than due to death), then the Deferred Compensation Separation Benefits that are payable within the first six (6) months following the Executive’s separation from service, will become payable on the first payroll date that occurs on or after the date six (6) months and one (1) day following the date of the Executive’s separation from service. All subsequent Deferred Compensation Separation Benefits, if any, will be payable in accordance with the payment schedule applicable to each payment or benefit. Notwithstanding anything herein to the contrary, if the Executive dies following the Executive’s separation from service but prior to the six (6) month anniversary of the separation, then any payments delayed in accordance with this paragraph will be payable in a lump sum as soon as administratively practicable after the date of the Executive’s death and all other Deferred Compensation Separation Benefits will be payable in accordance with the payment schedule applicable to each payment or benefit. Each payment and benefit payable under this Agreement is intended to constitute separate payments for purposes of Section 1.409A-2(b)(2) of the Treasury Regulations.

(iii) Any amount paid under this Agreement that satisfies the requirements of the “short-term deferral” rule set forth in Section 1.409A-1(b)(4) of the Treasury Regulations will not constitute Deferred Compensation Separation Benefits for purposes of clause (i) above.

(iv) Any amount paid under this Agreement that qualifies as a payment made as a result of an involuntary separation from service pursuant to Section 1.409A-1(b)(9)(iii) of the Treasury Regulations that do not exceed the Section 409A Limit (as defined below) will not constitute Deferred Compensation Separation Benefits for purposes of clause (i) above.

(v) “Section 409A Limit” will mean the lesser of two (2) times: (A) the Executive’s annualized compensation based upon the annual rate of pay paid to the Executive during the Executive’s taxable year preceding the Executive’s taxable year of the Executive’s termination of employment as determined under, and with such adjustments as are set forth in, Treasury Regulation 1.409A-1(b)(9)(iii)(A)(1) and any Internal Revenue Service guidance issued with respect thereto, or (B) the maximum amount that may be taken into account under a qualified plan pursuant to Section 401(a)(17) of the Code for the year in which the Executive’s employment is terminated.

(vi) The foregoing provisions are intended to comply with the requirements of Section 409A so that none of the severance payments and benefits to be provided hereunder will be subject to the additional tax imposed under Section 409A, and any ambiguities herein will be interpreted to so comply. The Company and the Executive agree to work together in good faith to consider amendments to this Agreement and to take such reasonable actions which are necessary, appropriate or desirable to avoid imposition of any additional tax or income recognition prior to actual payment to the Executive under Section 409A.”

7. Tax Provisions. Section 13 of the Agreement, entitled “Tax Provisions,” is hereby amended to read in its entirety as follows:

“13. Tax Provisions. In the event that the benefits provided for in the Agreement, when aggregated with any other payments or benefits received by the Executive, would (i) constitute “parachute payments” within the meaning of Section 280G of the Code, and (ii) would be subject to the excise tax imposed by Section 4999 of the Code (the “Excise Tax”), then the Executive shall receive a payment from the Company sufficient to pay the Excise Tax, less applicable tax withholding. The payment of any additional excise tax and federal and state income, employment or other taxes arising from the payment made by the Company to the Executive pursuant to the previous sentence shall be the sole responsibility of the Executive. The Company shall pay any amount as soon as reasonably practicable, but in no event later than the end of the Executive’s taxable year next following the Executive’s taxable year in which the Executive remits the related taxes. Unless the Company and the Executive otherwise agree in writing, any determination required under this paragraph shall be made in writing by the Company’s independent public accountants (the “Accountants”) whose determination shall be conclusive and binding upon the Executive and the Company for all purposes. For purposes of making the calculations required by this paragraph, the Accountants may make reasonable assumptions and approximations concerning applicable taxes and may rely on reasonable, good faith interpretations concerning the application of Sections 280G and 4999 of the Code. The Company and the Executive shall furnish to the Accountants such information and documents as the Accountants may reasonably request in order to make a determination under this paragraph. The provisions of this Section 13 shall survive the termination of this Agreement and the Executive’s employment with the Company.”

8. Full Force and Effect. To the extent not expressly amended hereby, the Agreement shall remain in full force and effect.

9. Entire Agreement. This Amendment and the Agreement constitute the full and entire understanding and agreement between the parties with regard to the subjects hereof and thereof.

10. Successors and Assigns. This Amendment and the rights and obligations of the parties hereunder shall inure to the benefit of, and be binding upon, their respective successors, assigns, and legal representatives.

11. Counterparts. This Amendment may be executed in counterparts, all of which together shall constitute one instrument, and each of which may be executed by less than all of the parties to this Amendment.

12. Governing Law. This Amendment shall be governed in all respects by the internal laws of California, without regard to principles of conflicts of law.

13. Amendment. Any provision of this Amendment may be amended, waived or terminated by a written instrument signed by the Company and the Executive.

(Signature page follows)

IN WITNESS WHEREOF, the undersigned parties have caused this Amendment to be executed as of the date first set forth above.

SARIA TSENG	MONOLITHIC POWER SYSTEMS,
	INC.
/s/ Saria Tseng	/s/ Michael Hsing
Signature	Signature
Saria Tseng	Michael Hsing
Print Name	Print Name
	President and CEO
	Print Title

(Signature page to Amendment to Saria Tseng Employment Agreement)

EX-21.1

Exhibit 21.1

SUBSIDIARIES OF MONOLITHIC POWER SYSTEMS, INC.

MPS International Ltd. 

MPS International (Shanghai) Ltd. 

Chengdu Monolithic Power Systems Co., Ltd.

MPS International Korea Co., Ltd.

MPS International GK

MPS Japan K.K.

MPS Europe SARL

Hangzhou MPS Semiconductor Technology LTD.

MPS International (Taiwan) Ltd. 

Monolithic Power Systems (Singapore) Pte. Ltd. 

MPS Germany GmbH

MPS Tech Switzerland SARL

Monolithic Power Spain, S.L.

EX-23.1

EXHIBIT 23.1

CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We consent to the incorporation by reference in the following Registration Statements:

(1) Registration Statement (Form S-8 No. 333-199782) pertaining to the Monolithic Power Systems, Inc. 2014 Equity Incentive Plan,

(2) Registration Statement (Form S-8 No. 333-198856) pertaining to the Monolithic Power Systems, Inc. 2004 Equity Incentive Plan,

(3) Registration Statement (Form S-8 No. 333-187117) pertaining to the Monolithic Power Systems, Inc. 2004 Equity Incentive Plan and the Monolithic Power Systems, Inc. 2004 Employee Stock Purchase Plan,

(4) Registration Statement (Form S-8 No. 333-180047) pertaining to the Monolithic Power Systems, Inc. 2004 Equity Incentive Plan and the Monolithic Power Systems, Inc. 2004 Employee Stock Purchase Plan,

(5) Registration Statement (Form S-8 No. 333-172013) pertaining to the Monolithic Power Systems, Inc. 2004 Equity Incentive Plan and the Monolithic Power Systems, Inc. 2004 Employee Stock Purchase Plan,

(6) Registration Statement (Form S-8 No. 333-164673) pertaining to the Monolithic Power Systems, Inc. 2004 Equity Incentive Plan and the Monolithic Power Systems, Inc. 2004 Employee Stock Purchase Plan,

(7) Registration Statement (Form S-8 No. 333-157095) pertaining to the Monolithic Power Systems, Inc. 2004 Equity Incentive Plan and the Monolithic Power Systems, Inc. 2004 Employee Stock Purchase Plan,

(8) Registration Statement (Form S-8 No. 333-149027) pertaining to the Monolithic Power Systems, Inc. 2004 Equity Incentive Plan and the Monolithic Power Systems, Inc. 2004 Employee Stock Purchase Plan,

(9) Registration Statement (Form S-8 No. 333-140563) pertaining to the Monolithic Power Systems, Inc. 2004 Equity Incentive Plan and the Monolithic Power Systems, Inc. 2004 Employee Stock Purchase Plan,

(10) Registration Statement (Form S-8 No. 333-132411), as amended, pertaining to the Monolithic Power Systems, Inc. 2004 Equity Incentive Plan and the Monolithic Power Systems, Inc. 2004 Employee Stock Purchase Plan, and

(11) Registration Statement (Form S-8 No. 333-120886) pertaining to the Monolithic Power Systems, Inc. 2004 Equity Incentive Plan, the Monolithic Power Systems, Inc. 2004 Employee Stock Purchase Plan and the Monolithic Power Systems, Inc. 1998 Stock Plan;

of our reports dated February 28, 2020 with respect to the consolidated financial statements of Monolithic Power Systems, Inc., and the effectiveness of internal control over financial reporting of Monolithic Power Systems, Inc. included in this Annual Report (Form 10-K) for the year ended December 31, 2019.

/s/ Ernst & Young LLP

San Jose, California

February 28, 2020

EX-23.2

EXHIBIT 23.2

CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We consent to the incorporation by reference in Registration Statement Nos. 333-199782, 333-198856, 333-187117, 333-180047, 333-172013, 333-164673, 333-157095, 333-149027, 333-140563, 333-132411, and 333-120886 on Form S-8 of our report dated March 1, 2019, relating to the consolidated financial statements of Monolithic Power Systems, Inc. and subsidiaries (the “Company”), as of December 31, 2018 and for each of the two years in the period ended December 31, 2018, appearing in this Annual Report on Form 10-K for the year ended December 31, 2019.

/s/ Deloitte & Touche LLP

San Jose, California

February 28, 2020

EX-31.1

Exhibit 31.1

CERTIFICATION OF CHIEF EXECUTIVE OFFICER PURSUANT TO

SECURITIES EXCHANGE ACT RULES 13a-14(a) and 15d-14(a), AS ADOPTED PURSUANT TO

SECTION 302 OF THE SARBANES-OXLEY ACT OF 2002

I, Michael Hsing, certify that:

1. I have reviewed this Annual Report on Form 10-K of Monolithic Power Systems, Inc.;

2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3. Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4. The registrant’s other certifying officer(s) and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

(a) Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

(b) Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

(c) Evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

(d) Disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

5. The registrant’s other certifying officer(s) and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant’s auditors and the audit committee of the registrant’s board of directors (or persons performing the equivalent functions):

(a) All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize and report financial information; and

(b) Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal control over financial reporting.

Date: February 28, 2020

/s/ Michael Hsing

Michael Hsing

Chief Executive Officer

EX-31.2

Exhibit 31.2

CERTIFICATION OF CHIEF FINANCIAL OFFICER PURSUANT TO

SECURITIES EXCHANGE ACT RULES 13a-14(a) and 15d-14(a), AS ADOPTED PURSUANT TO

SECTION 302 OF THE SARBANES-OXLEY ACT OF 2002

I, T. Bernie Blegen, certify that:

1. I have reviewed this Annual Report on Form 10-K of Monolithic Power Systems, Inc.;

2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3. Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4. The registrant’s other certifying officer(s) and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

(a) Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

(b) Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

(c) Evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

(d) Disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

5. The registrant’s other certifying officer(s) and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant’s auditors and the audit committee of the registrant’s board of directors (or persons performing the equivalent functions):

(a) All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize and report financial information; and

(b) Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal control over financial reporting.

Date: February 28, 2020

/s/ T. Bernie Blegen

T. Bernie Blegen

Chief Financial Officer

EX-32.1

Exhibit 32.1

The following certification shall not be deemed “filed” for purposes of section 18 of the Securities Exchange Act of 1934 or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933 or the Securities Exchange Act of 1934, whether made before or after the date hereof and irrespective of any general incorporation language in any filings.

CERTIFICATION OF CHIEF EXECUTIVE OFFICER AND

CHIEF FINANCIAL OFFICER PURSUANT TO

18 U.S.C. SECTION 1350, AS ADOPTED PURSUANT TO

SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with the Annual Report on Form 10-K of Monolithic Power Systems, Inc., a Delaware corporation, for the year ended December 31, 2019 (the “Report”), as filed with the Securities and Exchange Commission, each of the undersigned officers of Monolithic Power Systems, Inc. certifies pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that:

(1) the accompanying Report fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934, as amended; and

(2) the information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of Monolithic Power Systems, Inc. for the periods presented therein.

Date: February 28, 2020

/s/ Michael Hsing

Michael Hsing

Chief Executive Officer

Date: February 28, 2020

/s/ T. Bernie Blegen

T. Bernie Blegen

Chief Financial Officer

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Note 5 - Balance Sheet Components - Other Current Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
RSU tax withholding proceeds receivable	$ 6,106	$ 39
Prepaid expense	7,991	3,425
Interest receivable	2,490	1,441
Assets for product returns	1,585	1,602
Prepaid wafer refund receivable	0	4,297
Other	1,433	1,127
Total	$ 19,605	$ 11,931

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Note 4 - Fair Value Measurements - Level 3 Investments (Details) - Auction Rate Securities [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Balance, auction rate securities	$ 3,241	$ 5,256
Change in unrealized gain (loss) included in other comprehensive income	147	(15)
Sale and settlement at par	(250)	(2,000)
Balance, auction rate securities	$ 3,138	$ 3,241

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Note 3 - Cash, Cash Equivalents, Investments and Restricted Cash - Investment Maturity Classification (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Due in less than 1 year	$ 147,532	$ 125,845
Due in 1 - 5 years	134,905	78,732
Due in greater than 5 years	3,138	3,241
Total	$ 285,575	$ 207,818

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Note 12 - Income Taxes - Components of Income Tax Provision (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Current:
Federal									$ 1,682	$ 11,023	$ 31,025
State									8	4	2
Foreign									3,105	2,992	1,967
Deferred:
Federal									(213)	(797)	(15,426)
Foreign									(301)	(8)	173
Income tax expense	$ 989	$ 2,761	$ 1,655	$ (1,123)	$ 5,046	$ 4,639	$ 2,908	$ 621	$ 4,281	$ 13,214	$ 17,741

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Note 8 - Stock-based Compensation - Stock-based Compensation Plan Expenses (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share based compensation expense	$ 78,699	$ 60,607	$ 52,617
Tax benefit related to stock-based compensation	2,754	4,383	5,054
Cost of Sales [Member]
Share based compensation expense	2,409	1,888	1,654
Research and Development Expense [Member]
Share based compensation expense	19,584	15,990	14,816
Selling, General and Administrative Expenses [Member]
Share based compensation expense	$ 56,706	$ 42,729	$ 36,147

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Note 9 - Dividends and Dividend Equivalents - Cash Dividends (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Dividend declared per share (in dollars per share)	$ 0.40	$ 1.60	$ 1.20	$ 0.80
Total amount		$ 69,196	$ 50,803	$ 33,145

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Note 13 - Commitments and Contingencies (Details Textual) $ in Millions	Dec. 31, 2019 USD ($)
Purchase Obligation, Total	$ 90.6

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Note 8 - Stock-based Compensation

12 Months Ended

Dec. 31, 2019

Notes to Financial Statements

Share-based Payment Arrangement [Text Block]

8.  STOCK-BASED COMPENSATION

2014 Equity Incentive Plan (as amended, the “2014 Plan”)

The Board of Directors adopted the 2014 Plan in  April 2013, and the stockholders approved it in  June 2013. In  October 2014, the Board of Directors approved certain amendments to the 2014 Plan. The 2014 Plan, as amended, became effective on  November 13, 2014 and provides for the issuance of up to 5.5 million shares. The 2014 Plan will expire on  November 13, 2024. As of  December 31, 2019, 1.6 million shares remained available for future issuance under the 2014 Plan. 

Stock-Based Compensation Expense

The Company recognized stock-based compensation expense as follows (in thousands):

	Year Ended December 31,
	2019		2018		2017
Cost of revenue	$	2,409	$	1,888	$	1,654
Research and development		19,584		15,990		14,816
Selling, general and administrative		56,706		42,729		36,147
Total stock-based compensation expense	$	78,699	$	60,607	$	52,617
Tax benefit related to stock-based compensation	$	2,754	$	4,383	$	5,054

RSUs

The Company’s RSUs include time-based RSUs, RSUs with performance conditions (“PSUs”), RSUs with market conditions (“MSUs”), and RSUs with both market and performance conditions (“MPSUs”). Vesting of awards with performance conditions or market conditions is subject to the achievement of pre-determined performance goals and the approval of such achievement by the Compensation Committee of the Board of Directors (the “Compensation Committee”). All awards include service conditions which require continued employment with the Company.

A summary of RSU activity is presented in the table below (in thousands, except per-share amounts):

	Time-Based RSUs					PSUs and MPSUs					MSUs					Total
	Number of Shares			Weighted-Average Grant Date Fair Value Per Share		Number of Shares			Weighted-Average Grant Date Fair Value Per Share		Number of Shares			Weighted-Average Grant Date Fair Value Per Share		Number of Shares			Weighted-Average Grant Date Fair Value Per Share
Outstanding at January 1, 2017		366		$	51.35		2,284		$	43.24		1,620		$	23.57		4,270		$	36.47
Granted		81		$	94.25		585	(1)	$	62.72		-		$	-		666		$	66.56
Vested		(175	)	$	48.35		(597	)	$	41.94		-		$	-		(772	)	$	43.39
Forfeited		(14	)	$	61.80		(6	)	$	49.82		-		$	-		(20	)	$	58.46
Outstanding at December 31, 2017		258		$	66.30		2,266		$	48.59		1,620		$	23.57		4,144		$	39.91
Granted		133		$	114.36		630	(1)	$	85.06		600		$	68.48		1,363		$	80.62
Vested		(136	)	$	60.23		(717	)	$	41.08		-		$	-		(853	)	$	44.13
Forfeited		(15	)	$	82.20		(5	)	$	63.16		(1	)	$	68.48		(21	)	$	76.92
Outstanding at December 31, 2018		240		$	95.38		2,174		$	61.61		2,219		$	35.69		4,633		$	50.94
Granted		52		$	141.32		512	(1)	$	99.88		-		$	-		564		$	103.68
Vested		(103	)	$	81.53		(656	)	$	53.72		(324	)	$	23.57		(1,083	)	$	47.34
Forfeited		(9	)	$	117.31		(43	)	$	42.72		(9	)	$	68.48		(61	)	$	57.01
Outstanding at December 31, 2019		180		$	115.45		1,987		$	74.50		1,886		$	37.63		4,053		$	59.16

(1) Amount reflects the number of awards that  may ultimately be earned based on management’s probability assessment of the achievement of performance conditions at each reporting period.

The intrinsic value related to vested RSUs was $138.3 million, $90.0 million and $74.0 million for the years ended December 31, 2019, 2018 and 2017, respectively. As of December 31, 2019, the total intrinsic value of all outstanding RSUs was $679.5 million, based on the closing stock price of $178.02. As of December 31, 2019, unamortized compensation expense related to all outstanding RSUs was $100.1 million with a weighted-average remaining recognition period of approximately three years. 

Cash proceeds from vested PSUs with a purchase price totaled $16.6 million and $10.6 million for the years ended  December 31, 2019 and 2018, respectively. There were no proceeds for the year ended December 31, 2017.

Time-Based RSUs

For the years ended December 31, 2019, 2018 and 2017, the Compensation Committee granted 52,000, 133,000, and 81,000 RSUs, respectively, with service conditions to non-executive employees and non-employee directors. The RSUs generally vest over four years for employees and one year for directors, subject to continued service with the Company.

PSUs and MPSUs

2019 PSUs:

In  February 2019, the Compensation Committee granted 151,000 PSUs to the executive officers, which represent a target number of shares to be earned based on the Company’s average two-year (2019 and 2020) revenue growth rate compared against the analog industry’s average two-year revenue growth rate as published by the Semiconductor Industry Association (“2019 Executive PSUs”). The maximum number of shares that an executive officer can earn is 300% of the target number of the 2019 Executive PSUs. 50% of the 2019 Executive PSUs will vest in the first quarter of 2021 if the pre-determined performance goals are met during the performance period. The remaining 2019 Executive PSUs will vest over the following two years on a quarterly basis. Assuming the achievement of the highest level of performance goals, the total stock-based compensation cost for the 2019 Executive PSUs is $46.6 million.

The 2019 Executive PSUs contain a purchase price feature, which requires the employees to pay the Company $30 per share upon vesting of the shares. Shares that do not vest will not be subject to the purchase price payment. The Company determined the grant date fair value of the 2019 Executive PSUs using the Black-Scholes model with the following assumptions: stock price of $130.67, expected term of 2.6 years, expected volatility of 29.0% and risk-free interest rate of 2.5%.

In  October 2018, the Compensation Committee granted 53,000 PSUs to certain non-executive employees, which represent a target number of shares to be earned based on the Company’s 2020 revenue goals for certain regions or product line divisions, or based on the Company’s average two-year (2019 and 2020) revenue growth rate compared against the analog industry’s average two-year revenue growth rate as published by the Semiconductor Industry Association (“2019 Non-Executive PSUs”). The maximum number of shares that an employee can earn is either 200% or 300% of the target number of the 2019 Non-Executive PSUs, depending on the job classification of the employee. 50% of the 2019 Non-Executive PSUs will vest in the first quarter of 2021 if the pre-determined performance goals are met during the performance period. The remaining 2019 Non-Executive PSUs will vest over the following two years on an annual or quarterly basis. Assuming the achievement of the highest level of performance goals, the total stock-based compensation cost for the 2019 Non-Executive PSUs is $10.9 million.

The 2019 Non-Executive PSUs contain a purchase price feature, which requires the employees to pay the Company $30 per share upon vesting of the shares. Shares that do not vest will not be subject to the purchase price payment. The Company determined the grant date fair value of the 2019 Non-Executive PSUs using the Black-Scholes model with the following assumptions: stock price of $108.43, expected term of 2.9 years, expected volatility of 28.7% and risk-free interest rate of 2.9%. 

2018 PSUs:

In  February 2018, the Compensation Committee granted 188,000 PSUs to the executive officers, which represent a target number of shares to be earned based on the Company’s average two-year (2018 and 2019) revenue growth rate compared against the analog industry’s average two-year revenue growth rate as published by the Semiconductor Industry Association (“2018 Executive PSUs”). The maximum number of shares that an executive officer can earn is 300% of the target number of the 2018 Executive PSUs. 50% of the 2018 Executive PSUs will vest in the first quarter of 2020 if the pre-determined performance goals are met during the performance period. The remaining 2018 Executive PSUs will vest over the following two years on a quarterly basis. Assuming the achievement of the highest level of performance goals, the total stock-based compensation cost for the 2018 Executive PSUs is $46.1 million.

In  February 2018, the Compensation Committee granted 44,000 PSUs to certain non-executive employees, which represent a target number of shares to be earned based on the Company’s 2019 revenue goals for certain regions or product line divisions, or based on the Company’s average two-year (2018 and 2019) revenue growth rate compared against the analog industry’s average two-year revenue growth rate as published by the Semiconductor Industry Association (“2018 Non-Executive PSUs”). The maximum number of shares that an employee can earn is either 200% or 300% of the target number of the 2018 Non-Executive PSUs, depending on the job classification of the employee. 50% of the 2018 Non-Executive PSUs will vest in the first quarter of 2020 if the pre-determined performance goals are met during the performance period. The remaining 2018 Non-Executive PSUs will vest over the following two years on an annual or quarterly basis. Assuming the achievement of the highest level of performance goals, the total stock-based compensation cost for the 2018 Non-Executive PSUs, excluding cancelled shares for the terminated employees, is $8.8 million.

The 2018 Executive PSUs and the 2018 Non-Executive PSUs contain a purchase price feature, which requires the employees to pay the Company $30 per share upon vesting of the shares. Shares that do not vest will not be subject to the purchase price payment. The Company determined the grant date fair value of the 2018 Executive PSUs and the 2018 Non-Executive PSUs using the Black-Scholes model with the following assumptions: stock price of $110.00, expected term of 2.6 years, expected volatility of 27.5% and risk-free interest rate of 2.3%. 

2017 PSUs:

In February 2017, the Compensation Committee granted 200,000 PSUs to the executive officers, which represented a target number of shares that would be earned based on the Company’s average two-year (2017 and 2018) revenue growth rate compared against the analog industry’s average two-year revenue growth rate as published by the Semiconductor Industry Association (“2017 Executive PSUs”). The maximum number of shares that an executive officer could earn was 300% of the target number of the 2017 Executive PSUs. In  February 2019, the Compensation Committee approved the revenue achievement for the 2017 Executive PSUs and a total of 521,000 shares were awarded to the executive officers. 50% of the 2017 Executive PSUs vested in the first quarter of 2019. The remaining 2017 Executive PSUs vest over the following two years on a quarterly basis. Based on the actual achievement of the performance goals, the total stock-based compensation cost for the 2017 Executive PSUs is $31.5 million.

In February 2017, the Compensation Committee granted 48,000 PSUs to certain non-executive employees, which represented a target number of shares that would be earned based on the Company’s 2018 revenue goals for certain regions or product line divisions, or based on the Company’s average two-year (2017 and 2018) revenue growth rate compared against the analog industry’s average two-year revenue growth rate as published by the Semiconductor Industry Association (“2017 Non-Executive PSUs”). The maximum number of shares that an employee could earn was either 200% or 300% of the target number of the 2017 Non-Executive PSUs, depending on the job classification of the employee. In  February 2019, the Compensation Committee approved the revenue achievement for the 2017 Non-Executive PSUs and a total of 101,000 shares were awarded to the employees. 50% of the 2017 Non-Executive PSUs vested in the first quarter of 2019. The remaining 2017 Non-Executive PSUs vest over the following two years on an annual or quarterly basis. Based on the actual achievement of the performance goals, the total stock-based compensation cost for the 2017 Non-Executive PSUs, excluding cancelled shares for the terminated employees, is $6.1 million.

The 2017 Executive PSUs and the 2017 Non-Executive PSUs contain a purchase price feature, which requires the employees to pay the Company $30 per share upon vesting of the shares. Shares that do not vest will not be subject to the purchase price payment. The Company determined the grant date fair value of the 2017 Executive PSUs and the 2017 Non-Executive PSUs using the Black-Scholes model with the following assumptions: stock price of $89.37, expected term of 2.6 years, expected volatility of 28.6% and risk-free interest rate of 1.3%. 

2015 MPSUs:

In December 2015, the Compensation Committee granted 86,000 MPSUs to the executive officers and 41,000 MPSUs to certain non-executive employees, which represented a target number of shares that would be earned upon achievement of both market conditions and performance conditions (“2015 MPSUs”). The maximum number of shares that an employee could earn was 500% of the target number of the 2015 MPSUs. The 2015 MPSUs consisted of four separate tranches with various performance periods all ended on  December 31, 2019. The first tranche contained market conditions only, which required the achievement of five stock price targets ranging from $71.36 to $95.57 with a performance period from  January 1, 2016 to  December 31, 2019. 

The second, third and fourth tranches contained both market and performance conditions. The five stock price targets for the second tranche ranged from $89.56 to $106.81 with a performance period from  January 1, 2017 to  December 31, 2019. The five stock price targets for the third tranche ranged from $120.80 to $135.48 with a performance period from  January 1, 2018 to  December 31, 2019. The five stock price targets for the fourth tranche ranged from $126.08 to $136.79 with a performance period from  January 1, 2019 to  December 31, 2019.

In addition, each of the second, third and fourth tranches required the achievement of one of following six operating metrics:

1.	Successful implementation of full digital solutions for certain power products.
2.	Successful implementation, and adoption by a key customer, of an integrated, software-based field-oriented control with sensors to motor drivers.
3.	Successful implementation of certain advanced power analog processes.
4.	Successful design wins and achievement of a specific level of revenue with a global networking customer.
5.	Achievement of a specific level of revenue with a global electronics manufacturer.
6.	Achievement of a specific level of market share with certain core power products.

The following table summarizes the achievement of the market and performance conditions:

Tranche	Market Conditions	Performance Conditions
One	All stock price targets were achieved as of September 30, 2017.	Not required.
Two	All stock price targets were achieved as of December 31, 2017.	Operating metric #1 was achieved as of December 31, 2018.
Three	All stock price targets were achieved as of September 30, 2018.	Operating metric #2 was achieved as of December 31, 2018.
Four	All stock price targets were achieved as of March 31, 2019.	Operating metric #3 was achieved as of September 30, 2019.

A total of 0.6 million shares were awarded to the employees. The 2015 MPSUs will vest on  January 1, 2020, with post-vesting sales restrictions on the vested shares for up to an additional two years.

The Company determined the grant date fair value of the 2015 MPSUs using a Monte Carlo simulation model with the following weighted-average assumptions: stock price of $61.35, expected volatility of 33.2%, risk-free interest rate of 1.3%, and an illiquidity discount of 7.8% to account for the post-vesting sales restrictions. Based on the actual achievement of all of the market and performance goals, the total stock-based compensation cost for the 2015 MPSUs, excluding cancelled shares for the terminated employees, is $24.6 million ($8.3 million for the first tranche, $4.5 million for the second tranche, $5.2 million for the third tranche, and $6.6 million for the fourth tranche). 

MSUs

2018 MSUs:

In  October 2018, the Compensation Committee granted 60,000 MSUs to the executive officers and 60,000 MSUs to certain non-executive employees, which represented a target number of shares that would be earned upon achievement of stock price targets (“2018 MSUs”). The maximum number of shares that an employee could earn was 500% of the target number of the 2018 MSUs if the Company achieved five stock price targets ranging from $140 to $172 during a performance period from October 26, 2018 to December 31, 2023. As of December 31, 2019, all stock price targets have been achieved and the employees were awarded a total of 0.6 million shares. The 2018 MSUs will vest on  January 1, 2024, with post-vesting sales restrictions on the vested shares for up to an additional two years. The total stock-based compensation cost for the 2018 MSUs, excluding cancelled shares for the terminated employees, is $40.4 million.

The Company determined the grant date fair value of the 2018 MSUs using a Monte Carlo simulation model with the following assumptions: stock price of $108.43, expected volatility of 31.6%, a risk-free interest rate of 3.0%, and an illiquidity discount of 8.7% to account for the post-vesting sales restrictions. 

2013 MSUs:

In December 2013, the Compensation Committee granted 276,000 MSUs to the executive officers and 84,000 MSUs to certain non-executive employees, which represented a target number of shares that would be earned upon achievement of stock price targets (“2013 MSUs”). The maximum number of shares that an employee could earn was 500% of the target number of the 2013 MSUs if the Company achieved five price targets ranging from $40 to $56 during a performance period from January 1, 2014 to December 31, 2018. As of December 31, 2015, all stock price targets have been achieved and the employees were awarded a total of 1.8 million shares. The 2013 MSUs vest quarterly from January 1, 2019 to December 31, 2023. The total stock-based compensation cost for the 2013 MSUs, excluding cancelled shares for the terminated employees, is $38.2 million.

The Company determined the grant date fair value of the 2013 MSUs using a Monte Carlo simulation model with the following assumptions: stock price of $31.73, expected volatility of 38.7% and a risk-free interest rate of 1.6%. There was no illiquidity discount because the awards do not contain any post-vesting sales restrictions.

ESPP

Under the ESPP, eligible employees may purchase common stock through payroll deductions. Participants may not purchase more than 2,000 shares in a six-month offering period, or purchase shares having a value greater than $25,000 in any calendar year as measured at the beginning of the offering period in accordance with the Internal Revenue Code and applicable Treasury Regulations. The ESPP provides for an annual increase by an amount equal to the least of one million shares, 2% of the outstanding shares of common stock on the first day of the year, or a number of shares as determined by the Board of Directors. As of December 31, 2019, 4.5 million shares were available for future issuance. The ESPP will expire in November 2024.

For the years ended December 31, 2019, 2018 and 2017, 28,000, 33,000 and 40,000 shares, respectively, were issued. The intrinsic value of the shares issued was $0.7 million, $1.1 million and $1.0 million for the years ended December 31, 2019, 2018 and 2017, respectively. The unamortized expense was $0.1 million as of December 31, 2019, which will be recognized through the first quarter of 2020. The Black-Scholes model was used to value the employee stock purchase rights with the following weighted-average assumptions: 

	Year Ended December 31,
	2019			2018			2017
Expected term (in years)		0.5			0.5			0.5
Expected volatility		37.0	%		29.5	%		23.5	%
Risk-free interest rate		2.2	%		2.0	%		0.9	%
Dividend yield		1.1	%		1.0	%		0.9	%

Cash proceeds from the shares issued under the ESPP were $3.3 million, $3.0 million and $2.7 million for the years ended December 31, 2019, 2018 and 2017, respectively.

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Note 4 - Fair Value Measurements

12 Months Ended

Dec. 31, 2019

Notes to Financial Statements

Fair Value Disclosures [Text Block]

4. FAIR VALUE MEASUREMENTS

The following table details the fair value measurement of the financial assets (in thousands):

	December 31, 2019
	Total		Level 1		Level 2		Level 3
Money market funds	$	28,100	$	28,100	$	-	$	-
Corporate debt securities		260,950		-		260,950		-
Commercial paper		1,994		-		1,994		-
U.S. treasuries and government agency bonds		19,493		-		19,493		-
Auction-rate securities backed by student-loan notes		3,138		-		-		3,138
Mutual funds and money market funds under deferred compensation plan		21,975		21,975		-		-
Total	$	335,650	$	50,075	$	282,437	$	3,138

	December 31, 2018
	Total		Level 1		Level 2		Level 3
Money market funds	$	41,135	$	41,135	$	-	$	-
Corporate debt securities		170,909		-		170,909		-
U.S. treasuries and government agency bonds		32,068		-		32,068		-
Certificates of deposit		1,600		-		1,600		-
Auction-rate securities backed by student-loan notes		3,241		-		-		3,241
Mutual funds and money market funds under deferred compensation plan		18,867		18,867		-		-
Total	$	267,820	$	60,002	$	204,577	$	3,241

_______________

● Level 1—includes instruments with quoted prices in active markets for identical assets.

● Level 2—includes instruments for which the valuations are based upon quoted market prices in active markets involving similar assets or inputs other than quoted prices that are observable for the assets. The market inputs used to value these instruments generally consist of market yields, recently executed transactions, broker/dealer quotes or alternative pricing sources with reasonable levels of price transparency. Pricing sources  may include industry standard data providers, security master files from large financial institutions, and other third-party sources used to determine a daily market value.

● Level 3—includes instruments for which the valuations are based on inputs that are unobservable and significant to the overall fair value measurement.

The Company’s level 3 assets consist of government-backed student loan auction-rate securities. The following table provides a rollforward of the fair value of the auction-rate securities (in thousands): 

Balance at January 1, 2018	$	5,256
Change in unrealized loss included in other comprehensive income		(15	)
Sale and settlement at par		(2,000	)
Balance at December 31, 2018		3,241
Change in unrealized gain included in other comprehensive income		147
Sale and settlement at par		(250	)
Balance at December 31, 2019	$	3,138

The Company determined the fair value of the auction-rate securities using a discounted cash flow model with the following assumptions:

	December 31,
	2019			2018
Time-to-liquidity (in years)	2	-	3	2	-	3
Discount rate	4.0%	-	8.3%	4.9%	-	10.1%

The fair value measurement involves the analysis of valuation techniques and evaluation of unobservable inputs commonly used by market participants to price similar instruments. Outputs from the valuation process are assessed against various market sources when they are available, including marketplace quotes, recent trades of similar illiquid securities and independent pricing services. The valuation of the auction-rate securities is subject to significant management judgment regarding projected future cash flows, which will depend on many factors, including the quality of the underlying collateral, estimated time to liquidity including potential to be called or restructured, underlying final maturity, insurance guaranty and market conditions, among others. Changes in any of the unobservable inputs used in the fair value measurement of auction-rate securities in isolation would result in a lower or higher fair value measurement. For example, an increase in the time-to-liquidity assumption or estimated discount rate would result in a lower fair value measurement.

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Note 1 - Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2019

Notes Tables

Schedule of Deferred Compensation Plan [Table Text Block]

	December 31,
	2019		2018
Deferred compensation plan asset components:
Cash surrender value of corporate-owned life insurance policies	$	16,883	$	13,103
Fair value of mutual funds and money market funds		21,975		18,867
Total	$	38,858	$	31,970
Deferred compensation plan assets reported in:
Other long-term assets	$	38,858	$	31,970
Deferred compensation plan liabilities reported in:
Accrued compensation and related benefits (short-term)	$	425	$	447
Other long-term liabilities		39,665		32,283
Total	$	40,090	$	32,730

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Note 6 - Real Estate Transaction (Tables)

12 Months Ended

Dec. 31, 2019

Notes Tables

Asset Acquisition, Allocation of Consideration [Table Text Block]

Building	$	30,078
Land		22,254
In-place leases		981
Total	$	53,313

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Note 10 - Interest and Other Income, Net (Tables)

12 Months Ended

Dec. 31, 2019

Notes Tables

Schedule of Other Nonoperating Income (Expense) [Table Text Block]

	Year Ended December 31,
	2019			2018			2017
Interest income	$	7,305		$	6,321		$	5,353
Amortization of premium on available-for-sale securities		(729	)		(1,353	)		(1,976	)
Gain (loss) on deferred compensation plan investments		3,806			(1,022	)		2,531
Foreign currency exchange gain (loss)		(310	)		953			(550	)
Other		486			95			162
Total	$	10,558		$	4,994		$	5,520

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Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenue	$ 627,921	$ 582,382	$ 470,929
Cost of revenue	281,596	259,714	212,646
Gross profit	346,325	322,668	258,283
Operating expenses:
Research and development	107,757	93,455	82,359
Selling, general and administrative	133,542	113,803	97,257
Litigation expense	2,464	1,922	1,243
Total operating expenses	243,763	209,180	180,859
Income from operations	102,562	113,488	77,424
Interest and other income, net	10,558	4,994	5,520
Income before income taxes	113,120	118,482	82,944
Income tax expense	4,281	13,214	17,741
Net income	$ 108,839	$ 105,268	$ 65,203
Net income per share
Basic (in dollars per share)	$ 2.52	$ 2.49	$ 1.58
Diluted (in dollars per share)	$ 2.38	$ 2.36	$ 1.50
Weighted-average shares outstanding:
Basic (in shares)	43,165	42,247	41,350
Diluted (in shares)	45,763	44,602	43,578

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Consolidated Statements of Stockholders' Equity (Parentheticals) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Retained Earnings [Member]
Dividends and dividend equivalents declared per share (in dollars per share)	$ 1.60	$ 1.20	$ 0.80
Dividends and dividend equivalents declared per share (in dollars per share)	$ 1.60	$ 1.20	$ 0.80

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Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2019

Accounting Policies [Abstract]

Consolidation, Policy [Policy Text Block]

Basis of Presentation

The consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. Intercompany accounts and transactions have been eliminated in consolidation.

Use of Estimates, Policy [Policy Text Block]

Use of Estimates

The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America (“GAAP”) requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements, and reported amounts of revenue and expenses during the reporting period. Significant estimates and assumptions used in these consolidated financial statements primarily include those related to revenue recognition, inventory valuation, valuation of share-based awards, contingencies and income tax valuation allowances. Actual results could differ from those estimates. 

Concentration Risk, Credit Risk, Policy [Policy Text Block]

Certain Significant Risks and Uncertainties

Financial instruments which potentially subject the Company to concentrations of credit risk consist primarily of cash and cash equivalents, short-term and long-term investments and accounts receivable. The Company’s cash consists of checking and savings accounts. The Company’s cash equivalents include short-term, highly liquid investments purchased with remaining maturities at the date of purchase of three months or less. The Company’s short-term investments may consist of corporate debt securities, certificates of deposit, commercial paper and government agency bonds and treasuries, and the long-term investments consist of government-backed student loan auction-rate securities. The Company generally does not require its customers to provide collateral or other security to support accounts receivable. To manage credit risk, management performs ongoing credit evaluations of its customers’ financial condition, monitors payment performance, and, in some cases, requires standby letters of credit. The Company also requires payment in advance for certain customers prior to shipments of goods. 

The Company participates in the dynamic high technology industry and believes that changes in any of the following areas could have a material adverse effect on its future financial position, results of operations or cash flows: advances and trends in new technologies and industry standards; competitive pressures in the form of new products or price reductions on current products; changes in product mix; changes in the overall demand for products offered by the Company; changes in third-party manufacturers; changes in key suppliers; changes in certain strategic relationships or customer relationships; litigation or claims against the Company based on intellectual property, patent, product, regulatory or other factors; fluctuations in foreign currency exchange rates; risk associated with changes in government policies and regulations on trade restrictions and corporate taxes; availability of necessary components or sub-assemblies; availability of foundry capacity; ability to integrate acquired companies; and the Company’s ability to attract and retain employees necessary to support its growth.

Foreign Currency Transactions and Translations Policy [Policy Text Block]

Foreign Currency  

In general, the functional currency of the Company’s international subsidiaries is the local currency. The primary subsidiaries are located in China, Taiwan and Europe, which utilize the Renminbi, the New Taiwan Dollar and the Euro as their currencies, respectively. Accordingly, assets and liabilities of the foreign subsidiaries are translated using exchange rates in effect at the end of the period. Revenue and costs are translated using average exchange rates for the period. The resulting translation adjustments are presented as a separate component of accumulated other comprehensive loss in stockholders’ equity on the Consolidated Balance Sheets. In addition, the Company incurs foreign currency exchange gain or loss related to certain intercompany transactions between the U.S. and its foreign subsidiaries that are denominated in a currency other than the functional currency. In connection with the settlement and remeasurement of the balances, the Company recorded foreign currency exchange gain (loss) of $(0.3) million, $1.0 million and $(0.6) million for the years ended December 31, 2019, 2018 and 2017, respectively, which were reported in interest and other income, net, on the Consolidated Statements of Operations.

Cash and Cash Equivalents, Policy [Policy Text Block]

Cash, Cash Equivalents and Investments 

The Company classifies all highly liquid investments with stated maturities of three months or less from date of purchase as cash equivalents. The Company may classify investments with maturities beyond one year as short-term based on the nature of the investments and their availability for use in current operations.

Cash equivalents are stated at cost, which approximates fair market value. The Company’s short-term and long-term debt investments are classified as available-for-sale securities and are stated at their fair market value, with unrealized gains and losses recorded in accumulated other comprehensive loss. Premiums and discounts on debt investments are generally amortized or accreted over the life of the related available-for-sale securities. Interest income is recognized when earned. The cost of investments sold is determined on a specific identification method.

The Company’s available-for-sale investments are subject to periodic impairment reviews. When a decline in the fair value of a debt security below its amortized cost is considered other-than-temporary, the Company records an impairment charge in interest and other income, net.

Fair Value of Financial Instruments, Policy [Policy Text Block]

Fair Value of Financial Instruments

Fair value is defined as the price that would be received from selling an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. When determining the fair value, the Company considers the principal or most advantageous market in which the Company would transact, as well as assumptions that market participants would use when pricing the assets or liabilities. Fair value is estimated by applying the following hierarchy, which prioritizes the inputs used to measure fair value into three levels and bases the categorization within the hierarchy upon the lowest level of input that is available and significant to the fair value measurement:

● Level 1 - Observable inputs that reflect quoted prices (unadjusted) for identical assets or liabilities in active markets.

● Level 2 - Inputs that are based upon quoted prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are not active, and model-based valuation techniques for which all significant inputs are observable in the market or can be derived from observable market data.

● Level 3 - Significant unobservable inputs to the valuation methodology and typically reflect management’s estimates of assumptions that market participants would use in pricing the asset or liability.  

Inventory, Policy [Policy Text Block]

Inventories

Inventories are stated at the lower of standard cost (which approximates actual cost determined on a first-in first-out basis) and estimated net realizable value. The Company writes down excess and obsolete inventory based on its age and forecasted demand, which includes estimates taking into consideration the Company’s outlook on market and economic conditions, technology changes, new product introductions and changes in strategic direction. Actual demand may differ from forecasted demand, and such differences may have a material effect on recorded inventory values. When the Company records a write-down on inventory, it establishes a new, lower cost basis for that inventory, and subsequent changes in facts and circumstances will not result in the restoration or increase in that newly established cost basis.

Property, Plant and Equipment, Policy [Policy Text Block]

Property and Equipment

Property and equipment are stated at cost. Depreciation commences when an asset is placed in service and available for its intended use. Depreciation is computed using the straight-line method over the estimated useful lives of the assets. Buildings and building improvements have estimated useful lives of 20 to 40 years. Leasehold improvements are amortized over the shorter of the estimated useful lives or the lease period. Production equipment and software have estimated useful lives of three to eight years. Transportation equipment has estimated useful lives of 5 to 20 years. Furniture and fixtures have estimated useful lives of three to five years. Land is not depreciated.

Impairment or Disposal of Long-Lived Assets, Policy [Policy Text Block]

Impairment of Long-Lived Assets

The Company evaluates its long-lived assets other than goodwill for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. An impairment loss would be recognized when the sum of the undiscounted future net cash flows expected to result from the use of the asset and its eventual disposition is less than its carrying amount. Such impairment loss would be measured as the difference between the carrying amount of the asset and its fair value based on the present value of estimated future cash flows. The Company did not record material impairments in any of the periods presented.

Goodwill and Intangible Assets, Goodwill, Policy [Policy Text Block]

Goodwill

Goodwill represents the excess of the fair value of purchase consideration over the fair value of net tangible and identified intangible assets as of the date of acquisition. Goodwill is not amortized.

The Company tests goodwill for impairment at least annually in the fourth quarter of the year, or whenever events or changes in circumstances indicate that goodwill may be impaired. The Company has elected to first assess the qualitative factors to determine whether it is more likely than not that the fair value of the reporting unit is less than its carrying amount. If the Company determines that it is more likely than not that its fair value is less than the carrying amount, then a quantitative goodwill impairment test is performed to measure the impairment loss. No impairment of goodwill has been identified in any of the periods presented.  

Deferred Compensation Plan, Policy [Policy Text Block]

Deferred Compensation Plan 

The Company has a non-qualified, unfunded deferred compensation plan, which provides certain key employees, including executive officers, with the ability to defer the receipt of compensation in order to accumulate funds for retirement on a tax deferred basis. The Company does not make contributions to the plan or guarantee returns on the investments. The Company is responsible for the plan’s administrative expenses. Participants’ deferrals and investment gains and losses remain as the Company’s liabilities and the underlying assets are subject to claims of general creditors.

The liabilities for compensation deferred under the plan are recorded at fair value in each reporting period. Changes in the fair value of the liabilities are included in operating expense on the Consolidated Statements of Operations. The Company manages the risk of changes in the fair value of the liabilities by electing to match the liabilities with investments in corporate-owned life insurance policies, mutual funds and money market funds that offset a substantial portion of the exposure. The investments are recorded at the cash surrender value of the corporate-owned life insurance policies, and at the fair value of the mutual funds and money market funds, which are classified as trading securities. Changes in the cash surrender value of the corporate-owned life insurance policies and the fair value of mutual fund and money market fund investments are included in interest and other income, net on the Consolidated Statements of Operations. The following table summarizes the deferred compensation plan balances on the Consolidated Balance Sheets (in thousands):

	December 31,
	2019		2018
Deferred compensation plan asset components:
Cash surrender value of corporate-owned life insurance policies	$	16,883	$	13,103
Fair value of mutual funds and money market funds		21,975		18,867
Total	$	38,858	$	31,970
Deferred compensation plan assets reported in:
Other long-term assets	$	38,858	$	31,970
Deferred compensation plan liabilities reported in:
Accrued compensation and related benefits (short-term)	$	425	$	447
Other long-term liabilities		39,665		32,283
Total	$	40,090	$	32,730

Revenue from Contract with Customer [Policy Text Block]

Revenue Recognition

The Company recognizes revenue when it transfers control of promised goods or services to its customers in an amount that reflects the consideration to which it expects to be entitled to in exchange for those goods or services. See Note 2 for further discussion.

Research and Development Expense, Policy [Policy Text Block]

Research and Development

Costs incurred in research and development are expensed as incurred.

Standard Product Warranty, Policy [Policy Text Block]

Warranty Reserve

The Company generally provides one to two-year warranties against defects in materials and workmanship and will either repair the products, provide replacements at no charge to customers or issue a refund. As they are considered assurance-type warranties, the Company does not account for them as separate performance obligations. Warranty reserve requirements are generally based on a specific assessment of the products sold with warranties when a customer asserts a claim for warranty or a product defect. See Note 13 for the changes in warranty reserves for the periods presented.

Lessee, Leases [Policy Text Block]

Leases

The Company determines if an arrangement is a lease at inception. Lease terms may include options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. Operating lease right-of-use (“ROU”) assets represent the Company’s right to use an underlying asset for the lease term and operating lease liabilities represent the Company’s obligation to make lease payments arising from the lease. Operating lease ROU assets and liabilities are recognized at the commencement date based on the present value of remaining lease payments over the lease term. ROU assets also include any initial direct costs incurred and prepaid lease payments, less lease incentives received. Because the implicit rate in each lease is not readily determinable, the Company uses its estimated incremental borrowing rate to determine the present value of the remaining lease payment. The Company recognizes operating lease costs on a straight-line basis over the lease term.

The Company does not record short-term leases with a term of 12 months or less at the commencement date on the Consolidated Balance Sheets. For lease arrangements that contain lease and non-lease components, the Company accounts for them as single lease components.

For lease arrangements where the Company is the lessor, the Company recognizes lease income from operating leases on a straight-line basis over the lease term.

Share-based Payment Arrangement [Policy Text Block]

Stock-Based Compensation

The Company measures the cost of employee services received in exchange for an award of equity instruments based on the grant-date fair value of the award. The fair value of RSUs with service conditions or performance conditions is based on the grant date stock price. The fair value of shares issued under the ESPP and RSUs with a purchase price feature is estimated using the Black-Scholes model. The fair value of RSUs with market conditions, as well as RSUs containing both market and performance conditions, is estimated using a Monte Carlo simulation model. 

Compensation expense related to awards with service conditions is recorded on a straight-line basis over the requisite service period. Compensation expense related to awards subject to market or performance conditions is recognized over the requisite service period for each separately vesting tranche. For awards with only market conditions, compensation expense is not reversed if the market conditions are not satisfied. For awards with performance conditions, as well as awards containing both market and performance conditions, the Company recognizes compensation expense when the performance goals are achieved, or when it becomes probable that the performance goals will be achieved. Management performs the probability assessment on a quarterly basis by reviewing external factors, such as macroeconomic conditions and the analog industry revenue forecasts, and internal factors, such as the Company’s business and operational objectives and revenue forecasts. Changes in the probability assessment of achievement of the performance conditions are accounted for in the period of change by recording a cumulative catch-up adjustment as if the new estimate had been applied since the service inception date. Any previously recognized compensation expense is reversed if the performance conditions are not expected to be satisfied as a result of management’s assessment.

The Company accounts for forfeitures of equity awards when they occur.

Income Tax, Policy [Policy Text Block]

Accounting for Income Taxes 

The Company recognizes federal, state and foreign current tax liabilities or assets based on its estimate of taxes payable or refundable in the current fiscal year by tax jurisdiction. The Company also recognizes federal, state and foreign deferred tax assets or liabilities for its estimate of future tax effects attributable to temporary differences and carryforwards. The Company records a valuation allowance to reduce any deferred tax assets by the amount of any tax benefits that, based on available evidence and judgment, are not expected to be realized.

The Company’s calculation of current and deferred tax assets and liabilities is based on certain estimates and judgments and involves dealing with uncertainties in the application of complex tax laws. The Company’s estimates of current and deferred tax assets and liabilities may change based, in part, on added certainty, finality or uncertainty to an anticipated outcome, changes in accounting or tax laws in the U.S. or foreign jurisdictions where the Company operates, or changes in other facts or circumstances. In addition, the Company recognizes liabilities for potential U.S. and foreign income tax for uncertain income tax positions taken on its tax returns if it has less than a 50% likelihood of being sustained. If the Company determines that payment of these amounts is unnecessary or if the recorded tax liability is less than its current assessment, the Company may be required to recognize an income tax benefit or additional income tax expense in its financial statements in the period such determination is made. The Company has calculated its uncertain tax positions which were attributable to certain estimates and judgments.

Litigation and Contingencies, Policy [Policy Text Block]

Litigation and Contingencies

The Company is a party to actions and proceedings in the ordinary course of business, including potential litigation regarding its stockholders and its intellectual property, challenges to the enforceability or validity of its intellectual property, claims that the Company’s products infringe on the intellectual property rights of others, and employment matters. The pending proceedings involve complex questions of fact and law and will require the expenditure of significant funds and the diversion of other resources to prosecute and defend. In addition, from time to time, the Company becomes aware that it is subject to other contingent liabilities. When this occurs, the Company will evaluate the appropriate accounting for the potential contingent liabilities to determine whether a contingent liability should be recorded. In making this determination, management may, depending on the nature of the matter, consult with internal and external legal counsel and technical experts. Based on the facts and circumstances in each matter, the Company uses its judgment to determine whether it is probable that a contingent loss has occurred and whether the amount of such loss can be estimated. If the Company determines a loss is probable and estimable, the Company records a contingent loss. In determining the amount of a contingent loss, the Company takes into account advice received from experts for each specific matter regarding the status of legal proceedings, settlement negotiations, prior case history and other factors. Should the judgments and estimates made by management need to be adjusted as additional information becomes available, the Company may need to record additional contingent losses. Alternatively, if the judgments and estimates made by management are adjusted, for example, if a particular contingent loss does not occur, the contingent loss recorded would be reversed.

Litigation expense recorded on the Consolidated Statements of Operations includes primarily patent infringement litigation and other business matters. The Company records litigation costs in the period in which they are incurred. Proceeds resulting from settlement of litigation or favorable judgments are recorded as a reduction against litigation expense.

Earnings Per Share, Policy [Policy Text Block]

Net Income per Share

Basic net income per share is computed by dividing net income by the weighted-average number of common shares outstanding for the period. Diluted net income per share reflects the potential dilution that would occur if outstanding securities or other contracts to issue common stock were exercised or converted into common shares, and calculated using the treasury stock method. Contingently issuable shares, including equity awards with performance conditions or market conditions, are considered outstanding common shares and included in the basic net income per share as of the date that all necessary conditions to earn the awards have been satisfied. Prior to the end of the contingency period, the number of contingently issuable shares included in the diluted net income per share is based on the number of shares, if any, that would be issuable under the terms of the arrangement at the end of the reporting period.

The Company’s RSUs contain forfeitable rights to receive cash dividend equivalents, which are accumulated and paid to the employees when the underlying RSUs vest. Dividend equivalents accumulated on the underlying RSUs are forfeited if the employees do not fulfill the requisite service requirement and, as a result, the awards do not vest. Accordingly, these awards are not treated as participating securities in the net income per share calculation. 

Comprehensive Income, Policy [Policy Text Block]

Comprehensive Income 

Comprehensive income represents the change in the Company’s net assets during the period from non-owner sources. Accumulated other comprehensive loss presented on the Consolidated Balance Sheets primarily consists of unrealized gains or losses related to available-for-sale investments and foreign currency translation adjustments.

New Accounting Pronouncements, Policy [Policy Text Block]

Recently Adopted Accounting Pronouncement

In  February 2016, the FASB issued Accounting Standards Update (“ASU”) No. 2016-02, Leases (Topic 842), which requires entities to recognize ROU assets and lease liabilities on the balance sheets for leases with terms greater than 12 months. In addition, the standard applies to leases embedded in service or other arrangements. The Company adopted the standard on  January 1, 2019 using the modified retrospective transition method and did not restate comparative periods, as permitted by the standard. In addition, the Company elected the transition practical expedients to not reassess whether its outstanding contracts as of December 31, 2018 contained or were leases, classification of its existing leases and lease terms.

Upon adoption, the Company recognized ROU assets and lease liabilities of its outstanding operating leases on the Consolidated Balance Sheets, primarily related to real estate. The adoption did not have a material impact on the Consolidated Statements of Operations or the Consolidated Statements of Cash Flows. See Note 7 for further discussion.

Recent Accounting Pronouncements Not Yet Adopted as of December 31, 2019

In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes, which eliminates certain exceptions related to the approach for intra-period tax allocation, the methodology for calculating income taxes in an interim period and the recognition of deferred tax liabilities for outside basis differences. The standard also clarifies and simplifies other aspects of the accounting for income taxes. The standard will be effective for annual reporting periods beginning after December 15, 2020. Early adoption is permitted. The standard will generally be applied prospectively, with certain exceptions. The Company is evaluating the impact of the adoption on its consolidated financial statements.

In  August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework — Changes to the Disclosure Requirements for Fair Value Measurement, which changes certain disclosure requirements, including those related to Level 3 fair value measurements. The standard will be effective for annual reporting periods beginning after  December 15, 2019. The Company does not expect the adoption of this standard to have a material impact on its disclosures.

In  January 2017, the FASB issued ASU No. 2017-04, Intangibles – Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment, which simplifies the accounting for goodwill impairment. The guidance removes step two of the goodwill impairment test, which requires a hypothetical purchase price allocation to measure the amount of a goodwill impairment. A goodwill impairment will now be the amount by which a reporting unit’s carrying value exceeds its fair value, not to exceed the carrying amount of goodwill. Entities will continue to have the option to perform a qualitative assessment to determine if a quantitative impairment test is necessary. The standard will be applied prospectively, and will be effective for annual reporting periods beginning after  December 15, 2019. The Company will continue to perform the qualitative assessment on its goodwill impairment test and does not expect the adoption of this standard to have a material impact.

In  June 2016, the FASB issued ASU No. 2016-13, Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, which introduces a model based on expected losses to estimate credit losses for financial assets held at amortized cost. In addition, for available-for-sale debt securities, the standard eliminates the concept of other-than-temporary impairment and entities will be required to recognize an allowance for credit losses rather than reductions in the amortized cost of the securities. The standard will be effective for annual reporting periods beginning after  December 15, 2019. Entities will apply the standard by recording a cumulative-effect adjustment to retained earnings. The effect of the standard on the Company’s available-for-sale debt securities will largely depend on the composition of the investment portfolio, the financial condition of the issuers, the credit quality and expected collectability of the securities, and economic conditions. The Company does not expect the standard to have a material impact on its consolidated financial statements at the time of adoption.

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Note 16 - Segment and Geographic Information

12 Months Ended

Dec. 31, 2019

Notes to Financial Statements

Segment Reporting Disclosure [Text Block]

16.  SEGMENT AND GEOGRAPHIC INFORMATION 

The Company operates in one reportable segment that includes the design, development, marketing and sale of high-performance analog solutions for the computing and storage, automotive, industrial, communications and consumer markets. The Company’s chief operating decision maker is its Chief Executive Officer, who reviews financial information presented on a consolidated basis for purposes of allocating resources and evaluating financial performance. The Company derives a majority of its revenue from sales to customers located outside North America, with geographic revenue based on the customers’ ship-to locations.  

The following is a summary of revenue by geographic regions (in thousands):

	Year Ended December 31,
Country or Region	2019		2018		2017
China	$	382,740	$	334,726	$	257,787
Taiwan		73,801		75,307		83,357
Europe		49,467		49,484		38,140
Korea		43,900		41,238		34,155
Southeast Asia		32,031		36,495		25,755
Japan		27,812		26,853		20,187
United States		17,836		17,621		11,113
Other		334		658		435
Total	$	627,921	$	582,382	$	470,929

The following is a summary of revenue by major product families (in thousands):

	Year Ended December 31,
Product Family	2019		2018		2017
DC to DC	$	589,651	$	537,512	$	431,861
Lighting Control		38,270		44,870		39,068
Total	$	627,921	$	582,382	$	470,929

The following is a summary of long-lived assets by geographic regions (in thousands): 

	December 31,
Country	2019		2018		2017
China	$	113,888	$	93,096	$	89,472
United States		94,671		39,054		37,539
Taiwan		17,652		16,972		17,238
Other		2,104		879		387
Total	$	228,315	$	150,001	$	144,636

In 2019, the Company revised this disclosure presentation to exclude certain non-current items primarily related to goodwill and deferred compensation assets in accordance with ASC 280, Segment Reporting.  Prior-year amounts have been corrected.  These changes did not impact the Consolidated Balance Sheets.

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Note 12 - Income Taxes

12 Months Ended

Dec. 31, 2019

Notes to Financial Statements

Income Tax Disclosure [Text Block]

12.  INCOME TAXES

The components of income before income taxes are as follows (in thousands):

	Year Ended December 31,
	2019			2018			2017
United States	$	(4,134	)	$	(13,151	)	$	(19,115	)
Foreign		117,254			131,633			102,059
Income before income taxes	$	113,120		$	118,482		$	82,944

The components of the income tax expense are as follows (in thousands):

	Year Ended December 31,
	2019			2018			2017
Current:
Federal	$	1,682		$	11,023		$	31,025
State		8			4			2
Foreign		3,105			2,992			1,967
Deferred:
Federal		(213	)		(797	)		(15,426	)
Foreign		(301	)		(8	)		173
Income tax expense	$	4,281		$	13,214		$	17,741

The effective tax rate differs from the applicable U.S. statutory federal income tax rate as follows:

	Year Ended December 31,
	2019			2018			2017
U.S. statutory federal tax rate		21.0	%		21.0	%		35.0	%
Foreign income at lower rates		(20.7	)		(22.0	)		(41.2	)
Impact of the 2017 Tax Act:
Remeasurement of deferred taxes		-			-			11.8
One-time deemed repatriation transition tax		-			0.6			50.5
Global intangible low-taxed income (“GILTI”)		11.0			14.4			-
Changes in valuation allowance		2.1			-			(36.2	)
Stock-based compensation		(1.5	)		(1.1	)		2.2
Tax credits		(6.2	)		(1.9	)		(2.1	)
Other adjustments		(1.9	)		0.2			1.4
Effective tax rate		3.8	%		11.2	%		21.4	%

The components of net deferred tax assets consist of the following (in thousands):

	December 31,
	2019			2018
Deferred tax assets:
Tax credits	$	18,080		$	11,833
Stock-based compensation		6,237			10,040
Deferred compensation		7,110			6,829
Net operating losses		615			1,133
Other expenses not currently deductible		2,323			1,852
Deferred tax assets, gross		34,365			31,687
Valuation allowance		(15,411	)		(13,041	)
Deferred tax assets, net of valuation allowance		18,954			18,646
Deferred tax liabilities:
Depreciation and amortization		(1,259	)		(711	)
Undistributed foreign earnings		(77	)		(1,105	)
Other expenses currently deductible		(425	)		-
Deferred tax liabilities		(1,761	)		(1,816	)
Net deferred tax assets	$	17,193		$	16,830

Deemed Repatriation Transition Tax:

As permitted by the 2017 Tax Act, the Company has elected to pay the one-time, deemed repatriation transition tax liability of $24.6 million in installments on an interest-free basis over eight years through 2025. For the years ended December 31, 2019 and 2018, the Company paid $1.3 million and $2.6 million of the transition tax, respectively. As of December 31, 2019 and 2018, $2.0 million and $1.3 million of the transition tax were recorded in current accrued liabilities, and $18.7 million and $20.7 million were recorded in long-term income tax liabilities, respectively.

GILTI:

The 2017 Tax Act subjects a U.S. parent shareholder to taxation of its GILTI, effective January 1, 2018. The GILTI inclusions impact companies that have foreign earnings generated without a large aggregate foreign fixed asset base and whose earnings are being taxed at a low tax rate. For the years ended December 31, 2019 and 2018, the Company included $58.6 million and $81.1 million, respectively, related to the GILTI provisions as additional Subpart F income, which was accounted for as a period cost.

Valuation Allowance:

The Company periodically evaluates its deferred tax assets, including a determination of whether a valuation allowance is necessary, based upon its ability to utilize the assets using a more likely than not analysis. The realizability of the Company’s net deferred tax assets is dependent on its ability to generate sufficient future taxable income during periods prior to the expiration of tax attributes to fully utilize these assets. As of December 31, 2019 and 2018, the Company has evaluated and concluded that no valuation allowance is required, except for a continued full valuation allowance on the deferred tax assets in California.

Undistributed Earnings of Subsidiaries:

The Company has analyzed its global working capital and cash requirements, and has determined that it plans to repatriate cash from its Bermuda subsidiary on an ongoing basis to fund its future U.S.-based expenditures and dividends.  For the year ended December 31, 2019, the Company repatriated $75 million from its Bermuda subsidiary. As of December 31, 2019, the Company maintained an insignificant deferred tax liability related to California state taxes upon future repatriations.

For all other foreign subsidiaries, the Company expects to indefinitely reinvest undistributed earnings to fund their operations and research and development. As of December 31, 2019, the undistributed earnings were approximately $32.9 million. An actual repatriation of the undistributed earnings could be subject to additional foreign withholding taxes and U.S. state taxes. The Company expects to be able to take a 100% dividend received deduction to offset any U.S. federal income tax liability on the undistributed earnings. Determination of the unrecognized state and withholding deferred tax liability is not practicable at this time due to the complexities associated with the hypothetical calculation.

Other Income Tax Provision Matters

As of December 31, 2019, the Company did not have federal net operating loss carryforwards. As of December 31, 2019, the state net operating loss carryforwards for income tax purposes were $12.6 million, which will expire beginning in 2028.

As of December 31, 2019, the Company had no R&D tax credit carryforwards for federal income tax purposes, and $24.1 million for state income tax purposes, which can be carried forward indefinitely.

In the event of a change in ownership, as defined under federal and state tax laws, the Company's net operating loss and tax credit carryforwards could be subject to annual limitations. The annual limitations could result in the expiration of the net operating loss and tax credit carryforwards prior to utilization.

At December 31, 2019, the Company had $25.4 million of unrecognized tax benefits, $17.3 million of which would affect its effective tax rate if recognized after considering the valuation allowance. At December 31, 2018, the Company had $20.5 million of unrecognized tax benefits, $12.8 million of which would affect its effective tax rate if recognized after considering the valuation allowance.

A reconciliation of the gross unrecognized tax benefits is as follows (in thousands): 

Balance as of January 1, 2017	$	14,431
Increase for tax position of prior year		169
Increase for tax position of current year		2,360
Decrease due to lapse of statute of limitation		(688	)
Balance as of December 31, 2017		16,272
Increase for tax position of prior year		1,474
Increase for tax position of current year		2,957
Decrease due to lapse of statute of limitation		(212	)
Balance as of December 31, 2018		20,491
Increase for tax position of prior year		1,589
Increase for tax position of current year		4,663
Decrease due to settlement with tax authorities		(560	)
Decrease due to lapse of statute of limitation		(776	)
Balance as of December 31, 2019	$	25,407

The Company recognizes interest and penalties, if any, related to uncertain tax positions in its income tax provision. As of December 31, 2019 and 2018, the Company has $1.6 million and $0.9 million, respectively, of accrued interest related to uncertain tax positions, which were recorded in long-term income tax liabilities in the Consolidated Balance Sheets.

Uncertain tax positions relate to the allocation of income and deductions among the Company’s global entities and to the determination of the research and development tax credit. Various events, some of which cannot be predicted, such as clarification of tax law by administrative or judicial means, may occur and would require the Company to increase or decrease its reserves and effective income tax rate over the next twelve months. However, it is not possible to determine either the magnitude or the range of increases or decreases at this time.

The Company currently has reduced tax rates in its subsidiaries in Chengdu and Hangzhou, China through 2020 and 2021, respectively, for performing research and development activities.

In  July 2015, the U.S. Tax Court issued an opinion in Altera Corp. v. Commissioner, invalidating the Treasury regulations that require participants in qualified intercompany cost-sharing arrangements to share stock-based compensation costs. A final decision was issued by the Tax Court in  December 2015, and the IRS appealed the decision in  June 2016. In  June 2019, the Ninth Circuit Court of Appeals upheld the cost-sharing regulations. In  July 2019, Altera filed a petition for rehearing en banc in the Ninth Circuit Court of Appeals. In November 2019, the Ninth Circuit Court of Appeals declined to rehear the case. As of  December 31, 2019, it has not been determined if this ruling will be appealed. Due to the uncertainty surrounding the status of the current regulations, the Company has not recorded any adjustments as of  December 31, 2019. The Company will continue to monitor and evaluate the impact of any new developments on its financial statements. 

Income Tax Examination

The Company is subject to examination of its income tax returns by the IRS and other tax authorities. In general, the tax years for 2007 and forward are open for examination for U.S. federal and state income tax purposes. The Company is currently not under any significant tax examinations in any jurisdictions.

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Note 12 - Income Taxes (Tables)

12 Months Ended

Dec. 31, 2019

Notes Tables

Reconciliation of Operating Profit (Loss) from Segments to Consolidated [Table Text Block]

	Year Ended December 31,
	2019			2018			2017
United States	$	(4,134	)	$	(13,151	)	$	(19,115	)
Foreign		117,254			131,633			102,059
Income before income taxes	$	113,120		$	118,482		$	82,944

Schedule of Components of Income Tax Expense (Benefit) [Table Text Block]

	Year Ended December 31,
	2019			2018			2017
Current:
Federal	$	1,682		$	11,023		$	31,025
State		8			4			2
Foreign		3,105			2,992			1,967
Deferred:
Federal		(213	)		(797	)		(15,426	)
Foreign		(301	)		(8	)		173
Income tax expense	$	4,281		$	13,214		$	17,741

Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]

	Year Ended December 31,
	2019			2018			2017
U.S. statutory federal tax rate		21.0	%		21.0	%		35.0	%
Foreign income at lower rates		(20.7	)		(22.0	)		(41.2	)
Impact of the 2017 Tax Act:
Remeasurement of deferred taxes		-			-			11.8
One-time deemed repatriation transition tax		-			0.6			50.5
Global intangible low-taxed income (“GILTI”)		11.0			14.4			-
Changes in valuation allowance		2.1			-			(36.2	)
Stock-based compensation		(1.5	)		(1.1	)		2.2
Tax credits		(6.2	)		(1.9	)		(2.1	)
Other adjustments		(1.9	)		0.2			1.4
Effective tax rate		3.8	%		11.2	%		21.4	%

Schedule of Deferred Tax Assets and Liabilities [Table Text Block]

	December 31,
	2019			2018
Deferred tax assets:
Tax credits	$	18,080		$	11,833
Stock-based compensation		6,237			10,040
Deferred compensation		7,110			6,829
Net operating losses		615			1,133
Other expenses not currently deductible		2,323			1,852
Deferred tax assets, gross		34,365			31,687
Valuation allowance		(15,411	)		(13,041	)
Deferred tax assets, net of valuation allowance		18,954			18,646
Deferred tax liabilities:
Depreciation and amortization		(1,259	)		(711	)
Undistributed foreign earnings		(77	)		(1,105	)
Other expenses currently deductible		(425	)		-
Deferred tax liabilities		(1,761	)		(1,816	)
Net deferred tax assets	$	17,193		$	16,830

Schedule of Unrecognized Tax Benefits Roll Forward [Table Text Block]

Balance as of January 1, 2017	$	14,431
Increase for tax position of prior year		169
Increase for tax position of current year		2,360
Decrease due to lapse of statute of limitation		(688	)
Balance as of December 31, 2017		16,272
Increase for tax position of prior year		1,474
Increase for tax position of current year		2,957
Decrease due to lapse of statute of limitation		(212	)
Balance as of December 31, 2018		20,491
Increase for tax position of prior year		1,589
Increase for tax position of current year		4,663
Decrease due to settlement with tax authorities		(560	)
Decrease due to lapse of statute of limitation		(776	)
Balance as of December 31, 2019	$	25,407

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Note 17 - Accumulated Other Comprehensive Loss (Tables)

12 Months Ended

Dec. 31, 2019

Notes Tables

Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block]

	Unrealized Gains (Losses) on Available-for-Sale Securities			Foreign Currency Translation Adjustments			Total
Balance as of January 1, 2018	$	(1,364	)	$	3,177		$	1,813
Other comprehensive loss before reclassifications		(549	)		(7,082	)		(7,631	)
Amounts reclassified from accumulated other comprehensive income (loss)		66			-			66
Tax effect		209			-			209
Net current period other comprehensive loss		(274	)		(7,082	)		(7,356	)
Balance as of December 31, 2018		(1,638	)		(3,905	)		(5,543	)
Other comprehensive income (loss) before reclassifications		1,977			(1,706	)		271
Amounts reclassified from accumulated other comprehensive loss		(1	)		-			(1	)
Tax effect		(203	)		-			(203	)
Net current period other comprehensive income (loss)		1,773			(1,706	)		67
Balance as of December 31, 2019	$	135		$	(5,611	)	$	(5,476	)

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Note 2 - Revenue Recognition (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Lapse Period for Consignment	60 days
Accounts Receivable, after Allowance for Credit Loss, Current, Total	$ 52,704	$ 55,214
Accounts Receivable, Allowance for Credit Loss, Writeoff	0	0
Contract with Customer, Liability, Current	$ 3,412	2,520
Revenue, Performance Obligation, Performance Period Following Prepayment	14 days
Minimum [Member]
Contract with Customer, Payment Term	30 days
Maximum [Member]
Contract with Customer, Payment Term	60 days
Certain Customers in China [Member]
Contract with Customer, Payment Term Required Prior to Shipping Products	14 days
Contract with Customer, Liability, Revenue Recognized	$ 2,500
Certain Customers in China [Member] | Accrued Liabilities, Current [Member]
Contract with Customer, Liability, Current	$ 3,400	$ 2,500
Customer Concentration Risk [Member] | Revenue Benchmark [Member] | Distributor Sales [Member]
Concentration Risk, Percentage	83.00%	87.00%	88.00%
Product [Member]
Percentage of Revenue	99.00%	98.00%	98.00%

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Note 7 - Leases - Leases Cost (Details) - USD ($) $ in Thousands		12 Months Ended
	Jan. 01, 2019	Dec. 31, 2019
Operating lease costs		$ 1,509
Short-term and other lease costs		465
Total lease costs		1,974
Operating cash flows from operating leases		1,364
ROU assets obtained in exchange for new operating lease liabilities (1)	$ 2,300	$ 3,667	[1]
Weighted-average remaining lease term (in years) (Year)		2 years 1 month 6 days
Weighted-average discount rate		3.70%

[1] The amount includes $2.3 million for operating leases existing on January 1, 2019.

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Note 5 - Balance Sheet Components - Other Long-term Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred compensation plan liabilities	$ 39,665	$ 32,283
Dividend equivalents	6,265	6,145
Other	30	97
Total	47,063	38,525
Other Long-term Liabilities [Member]
Operating lease liabilities	$ 1,103	$ 0

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Note 16 - Segment and Geographic Information - Long Lived Assets by Geographic Region (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Long lived assets by region	$ 228,315	$ 150,001	$ 144,636
CHINA
Long lived assets by region	113,888	93,096	89,472
UNITED STATES
Long lived assets by region	94,671	39,054	37,539
TAIWAN, PROVINCE OF CHINA
Long lived assets by region	17,652	16,972	17,238
Other Region [Member]
Long lived assets by region	$ 2,104	$ 879	$ 387

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Consolidated Statements of Cash Flows $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Cash flows from operating activities:
Net income	$ 108,839	$ 105,268	$ 65,203
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	14,867	12,311	16,101
(Gain) loss on disposal and sale of property and equipment, net	(259)	22	(3)
Amortization of premium on available-for-sale securities	729	1,353	1,976
(Gain) loss on deferred compensation plan investments	(3,806)	255	(2,531)
Deferred taxes, net	(577)	(843)	(15,238)
Stock-based compensation expense	78,699	60,607	52,617
Changes in operating assets and liabilities:
Accounts receivable	2,512	(18,079)	(3,785)
Inventories	8,865	(37,060)	(27,795)
Other assets	(10,204)	(1,075)	1,603
Accounts payable	3,048	871	3,077
Accrued compensation and related benefits	7,496	3,806	2,397
Accrued liabilities	7,449	7,092	10,852
Income tax liabilities	(1,355)	6,923	29,347
Net cash provided by operating activities	216,303	141,451	133,821
Cash flows from investing activities:
Purchases of property and equipment	(95,806)	(22,526)	(65,770)
Acquisition of in-place leases	(981)	0	0
Purchases of short-term investments	(212,562)	(99,199)	(140,531)
Proceeds from maturities and sales of short-term investments	135,801	109,131	77,502
Proceeds from sales of long-term investments	250	2,000	0
Proceeds from sales of property and equipment	9,268	0	0
Contributions to deferred compensation plan, net	(3,082)	(4,146)	(5,261)
Net cash used in investing activities	(167,112)	(14,740)	(134,060)
Cash flows from financing activities:
Property and equipment purchased on extended payment terms	(683)	(749)	(250)
Proceeds from common stock issued under the employee equity incentive plan	16,650	10,637	150
Proceeds from common stock issued under the employee stock purchase plan	3,277	3,028	2,701
Dividends and dividend equivalents paid	(67,294)	(47,475)	(33,926)
Net cash used in financing activities	(48,050)	(34,559)	(31,325)
Effect of change in exchange rates	(883)	(2,208)	1,625
Net increase (decrease) in cash, cash equivalents and restricted cash	258	89,944	(29,939)
Cash, cash equivalents and restricted cash, beginning of period	172,818	82,874	112,813
Cash, cash equivalents and restricted cash, end of period	173,076	172,818	82,874
Supplemental disclosures for cash flow information:
Cash paid for taxes	10,700	7,134	3,619
Non-cash investing and financing activities:
Liability accrued for property and equipment purchases	7,803	1,737	3,061
Liability accrued for dividends and dividend equivalents	$ 21,955	$ 16,319	$ 10,686

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Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Net income	$ 108,839	$ 105,268	$ 65,203
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments	(1,706)	(7,082)	6,369
Change in unrealized gain (loss) on available-for-sale securities, net of tax of $(203), $209 and $0, respectively	1,773	(274)	(341)
Other comprehensive income (loss), net of tax	67	(7,356)	6,028
Comprehensive income	$ 108,906	$ 97,912	$ 71,231

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Document And Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2019	Feb. 19, 2020	Jun. 28, 2019
Document Information [Line Items]
Entity Central Index Key	0001280452
Entity Registrant Name	MONOLITHIC POWER SYSTEMS INC
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Document Fiscal Period Focus	FY
Document Fiscal Year Focus	2019
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2019
Document Transition Report	false
Entity File Number	000-51026
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	77-0466789
Entity Address, Address Line One	5808 Lake Washington Blvd. NE
Entity Address, City or Town	Kirkland
Entity Address, State or Province	WA
Entity Address, Postal Zip Code	98033
City Area Code	425
Local Phone Number	296-9956
Title of 12(b) Security	Common Stock, par value $0.001 per share
Trading Symbol	MPWR
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Public Float			$ 4,300,000,000
Entity Common Stock, Shares Outstanding		44,602,000

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Note 15 - Significant Customers

12 Months Ended

Dec. 31, 2019

Notes to Financial Statements

Concentration Risk Disclosure [Text Block]

15.  SIGNIFICANT CUSTOMERS

The Company sells its products primarily through third-party distributors and value-added resellers, and directly to OEMs, ODMs and EMS providers. The following table summarizes those customers with sales equal to 10% or more of the Company's total revenue, or with accounts receivable balances equal to 10% or more of the Company’s total accounts receivable: 

	Revenue									Accounts Receivable
	Year Ended December 31,									December 31,
Customer	2019			2018			2017			2019			2018
Company A (distributor)		23	%		22	%		17	%		24	%		25	%
Company B (distributor)		*			10	%		*			11	%		16	%
Company C (distributor)		*			*			10	%		*			*
Company A (value-added reseller)		*			*			*			13	%		*

* Represents less than 10%.

The Company’s agreements with these third-party distributors and value-added reseller were made in the ordinary course of business and  may be terminated with or without cause by these customers with advance notice. Although the Company  may experience a short-term disruption in the distribution of its products and a short-term decline in revenue if its agreement with any of these customers was terminated, the Company believes that such termination would not have a material adverse effect on its financial statements because it would be able to engage alternative distributors, resellers and other distribution channels to deliver its products to end customers within a short period following the termination of the agreement with the customer.  

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Note 11 - Net Income Per Share

12 Months Ended

Dec. 31, 2019

Notes to Financial Statements

Earnings Per Share [Text Block]

11.   NET INCOME PER SHARE

The following table sets forth the computation of basic and diluted net income per share (in thousands, except per share amounts):

	Year Ended December 31,
	2019		2018		2017
Numerator:
Net income	$	108,839	$	105,268	$	65,203
Denominator:
Weighted-average outstanding shares - basic		43,165		42,247		41,350
Effect of dilutive securities		2,598		2,355		2,228
Weighted-average outstanding shares - diluted		45,763		44,602		43,578
Net income per share:
Basic	$	2.52	$	2.49	$	1.58
Diluted	$	2.38	$	2.36	$	1.50

Anti-dilutive common stock equivalents were not material in any of the periods presented.

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Note 19 - Quarterly Financial Data (Unaudited)

12 Months Ended

Dec. 31, 2019

Notes to Financial Statements

Quarterly Financial Information [Text Block]

19. QUARTERLY FINANCIAL DATA (UNAUDITED)

	Three Months Ended
	December 31, 2019		September 30, 2019		June 30, 2019		March 31, 2019
	(in thousands, except per share amounts)
Revenue	$	166,738	$	168,813	$	151,007	$	141,363
Cost of revenue		74,802		75,655		67,782		63,357
Gross profit		91,936		93,158		83,225		78,006
Operating expenses:
Research and development		27,011		27,742		27,545		25,458
Selling, general and administrative		33,240		34,692		35,058		30,553
Litigation expense		991		692		503		278
Total operating expenses		61,242		63,126		63,106		56,289
Income from operations		30,694		30,032		20,119		21,717
Interest and other income, net		2,731		2,257		2,229		3,341
Income before income taxes		33,425		32,289		22,348		25,058
Income tax expense (benefit)		989		2,761		1,655		(1,123	)
Net income	$	32,436	$	29,528	$	20,693	$	26,181
Net income per share:
Basic	$	0.75	$	0.68	$	0.48	$	0.61
Diluted	$	0.70	$	0.64	$	0.45	$	0.58
Weighted-average shares outstanding:
Basic		43,496		43,308		43,109		42,749
Diluted		46,503		45,833		45,483		45,232

	Three Months Ended
	December 31, 2018			September 30, 2018		June 30, 2018		March 31, 2018
	(in thousands, except per share amounts)
Revenue	$	153,497		$	159,975	$	139,761	$	129,150
Cost of revenue		68,904			70,957		62,197		57,655
Gross profit		84,593			89,018		77,564		71,495
Operating expenses:
Research and development		22,735			25,630		23,481		21,609
Selling, general and administrative		28,372			29,552		28,561		27,318
Litigation expense		409			343		640		531
Total operating expenses		51,516			55,525		52,682		49,458
Income from operations		33,077			33,493		24,882		22,037
Interest and other income (expense), net		(393	)		2,714		2,232		440
Income before income taxes		32,684			36,207		27,114		22,477
Income tax expense		5,046			4,639		2,908		621
Net income	$	27,638		$	31,568	$	24,206	$	21,856
Net income per share:
Basic	$	0.65		$	0.75	$	0.57	$	0.52
Diluted	$	0.61		$	0.71	$	0.55	$	0.49
Weighted-average shares outstanding:
Basic		42,467			42,362		42,237		41,922
Diluted		45,058			44,669		44,400		44,282

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Note 3 - Cash, Cash Equivalents, Investments and Restricted Cash (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 200	$ 1,600
Other-than-temporary Impairment Loss, Debt Securities, Available-for-sale, Total	$ 0
Auction Rate Securities Maturities	27 years
Redemption, Auction Rate Securities to Date	$ 40,000
Percentage of Auction Rate Securities Redeemed at Par Value	92.00%
Auction Rate Securities [Member]
Redemption Auction Rate Securities	$ 300	2,000	$ 0
Other than Temporary Impairment Losses, Investments, Total	$ 200	$ 300

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Note 13 - Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2019

Notes Tables

Schedule of Product Warranty Liability [Table Text Block]

	Year Ended December 31,
	2019			2018			2017
Balance at beginning of period	$	4,564		$	2,416		$	1,030
Warranty provision for product sales		891			6,586			1,912
Settlements made		(2,768	)		(1,402	)		(40	)
Unused warranty provision		(1,548	)		(3,036	)		(486	)
Balance at end of period	$	1,139		$	4,564		$	2,416

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Note 19 - Quarterly Financial Data (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2019

Notes Tables

Quarterly Financial Information [Table Text Block]

	Three Months Ended
	December 31, 2019		September 30, 2019		June 30, 2019		March 31, 2019
	(in thousands, except per share amounts)
Revenue	$	166,738	$	168,813	$	151,007	$	141,363
Cost of revenue		74,802		75,655		67,782		63,357
Gross profit		91,936		93,158		83,225		78,006
Operating expenses:
Research and development		27,011		27,742		27,545		25,458
Selling, general and administrative		33,240		34,692		35,058		30,553
Litigation expense		991		692		503		278
Total operating expenses		61,242		63,126		63,106		56,289
Income from operations		30,694		30,032		20,119		21,717
Interest and other income, net		2,731		2,257		2,229		3,341
Income before income taxes		33,425		32,289		22,348		25,058
Income tax expense (benefit)		989		2,761		1,655		(1,123	)
Net income	$	32,436	$	29,528	$	20,693	$	26,181
Net income per share:
Basic	$	0.75	$	0.68	$	0.48	$	0.61
Diluted	$	0.70	$	0.64	$	0.45	$	0.58
Weighted-average shares outstanding:
Basic		43,496		43,308		43,109		42,749
Diluted		46,503		45,833		45,483		45,232

	Three Months Ended
	December 31, 2018			September 30, 2018		June 30, 2018		March 31, 2018
	(in thousands, except per share amounts)
Revenue	$	153,497		$	159,975	$	139,761	$	129,150
Cost of revenue		68,904			70,957		62,197		57,655
Gross profit		84,593			89,018		77,564		71,495
Operating expenses:
Research and development		22,735			25,630		23,481		21,609
Selling, general and administrative		28,372			29,552		28,561		27,318
Litigation expense		409			343		640		531
Total operating expenses		51,516			55,525		52,682		49,458
Income from operations		33,077			33,493		24,882		22,037
Interest and other income (expense), net		(393	)		2,714		2,232		440
Income before income taxes		32,684			36,207		27,114		22,477
Income tax expense		5,046			4,639		2,908		621
Net income	$	27,638		$	31,568	$	24,206	$	21,856
Net income per share:
Basic	$	0.65		$	0.75	$	0.57	$	0.52
Diluted	$	0.61		$	0.71	$	0.55	$	0.49
Weighted-average shares outstanding:
Basic		42,467			42,362		42,237		41,922
Diluted		45,058			44,669		44,400		44,282

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Note 19 - Quarterly Financial Data (Unaudited) - Summary of Quarterly Financial Data (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenue	$ 166,738	$ 168,813	$ 151,007	$ 141,363	$ 153,497	$ 159,975	$ 139,761	$ 129,150	$ 627,921	$ 582,382	$ 470,929
Cost of revenue	74,802	75,655	67,782	63,357	68,904	70,957	62,197	57,655	281,596	259,714	212,646
Gross profit	91,936	93,158	83,225	78,006	84,593	89,018	77,564	71,495	346,325	322,668	258,283
Research and development	27,011	27,742	27,545	25,458	22,735	25,630	23,481	21,609	107,757	93,455	82,359
Selling, general and administrative	33,240	34,692	35,058	30,553	28,372	29,552	28,561	27,318	133,542	113,803	97,257
Litigation expense	991	692	503	278	409	343	640	531
Total operating expenses	61,242	63,126	63,106	56,289	51,516	55,525	52,682	49,458	243,763	209,180	180,859
Income from operations	30,694	30,032	20,119	21,717	33,077	33,493	24,882	22,037	102,562	113,488	77,424
Interest and other income (expense), net	2,731	2,257	2,229	3,341	(393)	2,714	2,232	440	10,558	4,994	5,520
Income before income taxes	33,425	32,289	22,348	25,058	32,684	36,207	27,114	22,477	113,120	118,482	82,944
Income tax expense (benefit)	989	2,761	1,655	(1,123)	5,046	4,639	2,908	621	4,281	13,214	17,741
Net income	$ 32,436	$ 29,528	$ 20,693	$ 26,181	$ 27,638	$ 31,568	$ 24,206	$ 21,856	$ 108,839	$ 105,268	$ 65,203
Earnings per share, basic (in dollars per share)	$ 0.75	$ 0.68	$ 0.48	$ 0.61	$ 0.65	$ 0.75	$ 0.57	$ 0.52	$ 2.52	$ 2.49	$ 1.58
Earnings per share, diluted (in dollars per share)	$ 0.70	$ 0.64	$ 0.45	$ 0.58	$ 0.61	$ 0.71	$ 0.55	$ 0.49	$ 2.38	$ 2.36	$ 1.50
Weighted-average shares outstanding, basic (in shares)	43,496	43,308	43,109	42,749	42,467	42,362	42,237	41,922
Diluted (in shares)	46,503	45,833	45,483	45,232	45,058	44,669	44,400	44,282	45,763	44,602	43,578

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Note 7 - Leases (Details Textual) - USD ($) $ in Thousands		12 Months Ended
	Jan. 01, 2019	Dec. 31, 2019		Dec. 31, 2018	Dec. 31, 2017
Operating Lease, Right-of-Use Asset		$ 2,863		$ 0
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	$ 2,300	3,667	[1]
Operating Leases, Rent Expense, Net, Total				$ 1,800	$ 1,500
Operating Lease, Lease Income, Lease Payments		1,800
Other Assets [Member]
Operating Lease, Right-of-Use Asset		2,900
Other Liabilities [Member]
Operating Lease, Liability, Total		$ 2,400
Maximum [Member]
Lessee, Operating Lease, Remaining Lease Term		4 years
Lessee, Operating Lease, Renewal Term		5 years
Lessor, Remaining Lease Term		5 years
Lessor, Operating Lease, Renewal Term		5 years
Minimum [Member]
Lessor, Remaining Lease Term		1 year

[1] The amount includes $2.3 million for operating leases existing on January 1, 2019.

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Note 5 - Balance Sheet Components - Accrued Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Dividends and dividend equivalents	$ 21,747	$ 15,044
Stock rotation and sales returns	5,530	5,363
Customer prepayments	3,412	2,520
Income tax payable	2,435	7,018
Commissions	1,425	1,369
Warranty	1,139	4,564
Other	7,848	3,084
Total	44,790	38,962
Accrued Liabilities, Current [Member]
Operating lease liabilities	$ 1,254	$ 0

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Note 16 - Segment and Geographic Information - Revenue by Product Family (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenue	$ 166,738	$ 168,813	$ 151,007	$ 141,363	$ 153,497	$ 159,975	$ 139,761	$ 129,150	$ 627,921	$ 582,382	$ 470,929
DC To DC Products [Member]
Revenue									589,651	537,512	431,861
Lighting Control Products [Member]
Revenue									$ 38,270	$ 44,870	$ 39,068

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Note 4 - Fair Value Measurements - Financial Assets and Liabilities, Fair Value (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Total Fair Value	$ 313,675	$ 248,953
Assets, fair value	335,650	267,820
Fair Value, Inputs, Level 1 [Member]
Assets, fair value	50,075	60,002
Fair Value, Inputs, Level 2 [Member]
Assets, fair value	282,437	204,577
Fair Value, Inputs, Level 3 [Member]
Assets, fair value	3,138	3,241
Money Market Funds [Member]
Total Fair Value	28,100	41,135
Money Market Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Total Fair Value	28,100	41,135
Money Market Funds [Member] | Fair Value, Inputs, Level 2 [Member]
Total Fair Value	0	0
Money Market Funds [Member] | Fair Value, Inputs, Level 3 [Member]
Total Fair Value	0	0
Corporate Debt Securities [Member]
Total Fair Value	260,950	170,909
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Total Fair Value	0	0
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Total Fair Value	260,950	170,909
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Total Fair Value	0	0
Commercial Paper [Member]
Total Fair Value	1,994
Commercial Paper [Member] | Fair Value, Inputs, Level 1 [Member]
Total Fair Value	0
Commercial Paper [Member] | Fair Value, Inputs, Level 2 [Member]
Total Fair Value	1,994
Commercial Paper [Member] | Fair Value, Inputs, Level 3 [Member]
Total Fair Value	0
US Government Agencies Short-term Debt Securities [Member]
Total Fair Value	19,493	32,068
US Government Agencies Short-term Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Total Fair Value	0	0
US Government Agencies Short-term Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Total Fair Value	19,493	32,068
US Government Agencies Short-term Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Total Fair Value	0	0
Certificates of Deposit [Member]
Total Fair Value		1,600
Certificates of Deposit [Member] | Fair Value, Inputs, Level 1 [Member]
Total Fair Value		0
Certificates of Deposit [Member] | Fair Value, Inputs, Level 2 [Member]
Total Fair Value		1,600
Certificates of Deposit [Member] | Fair Value, Inputs, Level 3 [Member]
Total Fair Value		0
Auction Rate Securities [Member]
Total Fair Value	3,138	3,241
Auction Rate Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Total Fair Value	0	0
Auction Rate Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Total Fair Value	0	0
Auction Rate Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Total Fair Value	3,138	3,241
Mutual Fund [Member]
Total Fair Value	21,975	18,867
Mutual Fund [Member] | Fair Value, Inputs, Level 1 [Member]
Total Fair Value	21,975	18,867
Mutual Fund [Member] | Fair Value, Inputs, Level 2 [Member]
Total Fair Value	0	0
Mutual Fund [Member] | Fair Value, Inputs, Level 3 [Member]
Total Fair Value	$ 0	$ 0

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Note 3 - Cash, Cash Equivalents, Investments and Restricted Cash - Cash Equivalents, Short-term and Long-term Investments (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Cash	$ 144,860	$ 131,569
Money market funds	28,100	41,135
Commercial paper	1,994	0
U.S. treasuries and government agency bonds	19,493	32,068
Certificates of deposit	0	1,600
Total	458,535	380,522
Cash and cash equivalents	172,960	172,704
Short-term investments	282,437	204,577
Long-term investments	3,138	3,241
Corporate Debt Securities [Member]
Available-for-sale securities	260,950	170,909
Auction Rate Securities [Member]
Available-for-sale securities	$ 3,138	$ 3,241

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Note 5 - Balance Sheet Components - Inventories (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Raw materials	$ 22,872	$ 43,017
Work in process	42,681	38,674
Finished goods	61,947	54,693
Total	$ 127,500	$ 136,384

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Note 12 - Income Taxes - Income Tax Rate Reconciliation (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
U.S. statutory federal tax rate	21.00%	21.00%	35.00%
Foreign income at lower rates	(20.70%)	(22.00%)	(41.20%)
Remeasurement of deferred taxes			11.80%
One-time deemed repatriation transition tax		0.60%	50.50%
Global intangible low-taxed income (“GILTI”)	11.00%	14.40%
Changes in valuation allowance	2.10%		(36.20%)
Stock-based compensation	(1.50%)	(1.10%)	2.20%
Tax credits	(6.20%)	(1.90%)	(2.10%)
Other adjustments	(1.90%)	0.20%	1.40%
Effective tax rate	3.80%	11.20%	21.40%

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Note 8 - Stock-based Compensation - RSU Summary (Details) - $ / shares		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Beginning balance (in shares)		4,633,000	4,144,000	4,270,000
Weighted-Average Grant Date Fair Value Per Share, beginning balance (in dollars per share)		$ 50.94	$ 39.91	$ 36.47
Granted (in shares)		564,000	1,363,000	666,000
Weighted-Average Grant Date Fair Value Per Share, granted (in dollars per share)		$ 103.68	$ 80.62	$ 66.56
Vested (in shares)		(1,083,000)	(853,000)	(772,000)
Weighted-Average Grant Date Fair Value Per Share, vested (in dollars per share)		$ 47.34	$ 44.13	$ 43.39
Forfeited (in shares)		(61,000)	(21,000)	(20,000)
Weighted-Average Grant Date Fair Value Per Share, forfeited (in dollars per share)		$ 57.01	$ 76.92	$ 58.46
Ending balance (in shares)		4,053,000	4,633,000	4,144,000
Weighted-Average Grant Date Fair Value Per Share, ending balance (in dollars per share)		$ 59.16	$ 50.94	$ 39.91
Time-Based RSUs [Member]
Beginning balance (in shares)		240,000	258,000	366,000
Weighted-Average Grant Date Fair Value Per Share, beginning balance (in dollars per share)		$ 95.38	$ 66.30	$ 51.35
Granted (in shares)		52,000	133,000	81,000
Weighted-Average Grant Date Fair Value Per Share, granted (in dollars per share)		$ 141.32	$ 114.36	$ 94.25
Vested (in shares)		(103,000)	(136,000)	(175,000)
Weighted-Average Grant Date Fair Value Per Share, vested (in dollars per share)		$ 81.53	$ 60.23	$ 48.35
Forfeited (in shares)		(9,000)	(15,000)	(14,000)
Weighted-Average Grant Date Fair Value Per Share, forfeited (in dollars per share)		$ 117.31	$ 82.20	$ 61.80
Ending balance (in shares)		180,000	240,000	258,000
Weighted-Average Grant Date Fair Value Per Share, ending balance (in dollars per share)		$ 115.45	$ 95.38	$ 66.30
PSUs and MPSUs [Member]
Beginning balance (in shares)		2,174,000	2,266,000	2,284,000
Weighted-Average Grant Date Fair Value Per Share, beginning balance (in dollars per share)		$ 61.61	$ 48.59	$ 43.24
Granted (in shares)	[1]	512,000	630,000	585,000
Weighted-Average Grant Date Fair Value Per Share, granted (in dollars per share)		$ 99.88	$ 85.06	$ 62.72
Vested (in shares)		(656,000)	(717,000)	(597,000)
Weighted-Average Grant Date Fair Value Per Share, vested (in dollars per share)		$ 53.72	$ 41.08	$ 41.94
Forfeited (in shares)		(43,000)	(5,000)	(6,000)
Weighted-Average Grant Date Fair Value Per Share, forfeited (in dollars per share)		$ 42.72	$ 63.16	$ 49.82
Ending balance (in shares)		1,987,000	2,174,000	2,266,000
Weighted-Average Grant Date Fair Value Per Share, ending balance (in dollars per share)		$ 74.50	$ 61.61	$ 48.59
MSUs [Member]
Beginning balance (in shares)		2,219,000	1,620,000	1,620,000
Weighted-Average Grant Date Fair Value Per Share, beginning balance (in dollars per share)		$ 35.69	$ 23.57	$ 23.57
Granted (in shares)		0	600,000	0
Weighted-Average Grant Date Fair Value Per Share, granted (in dollars per share)		$ 0	$ 68.48	$ 0
Vested (in shares)		(324,000)	0	0
Weighted-Average Grant Date Fair Value Per Share, vested (in dollars per share)		$ 23.57	$ 0	$ 0
Forfeited (in shares)		(9,000)	(1,000)	0
Weighted-Average Grant Date Fair Value Per Share, forfeited (in dollars per share)		$ 68.48	$ 68.48	$ 0
Ending balance (in shares)		1,886,000	2,219,000	1,620,000
Weighted-Average Grant Date Fair Value Per Share, ending balance (in dollars per share)		$ 37.63	$ 35.69	$ 23.57

[1] Amount reflects the number of awards that may ultimately be earned based on management's probability assessment of the achievement of performance conditions at each reporting period.

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Note 10 - Interest and Other Income, Net (Details Textual) $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($)
Other Nonoperating Income (Expense) [Member] | Land [Member]
Gain (Loss) on Disposition of Property Plant Equipment, Excluding Oil and Gas Property and Timber Property	$ 0.7

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Note 13 - Commitments and Contingencies - Changes in Warranty Reserve (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Balance	$ 4,564	$ 2,416	$ 1,030
Warranty provision for product sales	891	6,586	1,912
Settlements made	(2,768)	(1,402)	(40)
Unused warranty provision	(1,548)	(3,036)	(486)
Balance	$ 1,139	$ 4,564	$ 2,416

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Note 7 - Leases

12 Months Ended

Dec. 31, 2019

Notes to Financial Statements

Leases Disclosure [Text Block]

7. LEASES

 Lessee

The Company has operating leases primarily for administrative and sales and marketing offices, manufacturing operations and research and development facilities, employee housing units and certain equipment. These leases have remaining lease terms from less than a year to four years. Some of these leases include options to renew the lease term for up to five years or on a month-to-month basis. The Company does not have finance lease arrangements.

As of  December 31, 2019, operating lease ROU assets totaled $2.9 million and operating lease liabilities totaled $2.4 million. The following tables summarize certain information related to the leases (in thousands, except percentages):

	Year Ended
	December 31, 2019
Lease costs:
Operating lease costs	$	1,509
Short-term and other lease costs		465
Total lease costs	$	1,974

	Year Ended
	December 31, 2019
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$	1,364
ROU assets obtained in exchange for new operating lease liabilities (1)	$	3,667

	December 31, 2019
Weighted-average remaining lease term (in years)		2.1
Weighted-average discount rate		3.7	%

(1) The amount includes $2.3 million for operating leases existing on  January 1, 2019.

As of  December 31, 2019, the maturities of the lease liabilities were as follows (in thousands):

2020	$	1,328
2021		734
2022		390
2023		22
Total remaining lease payments		2,474
Less: imputed interest		(117	)
Total lease liabilities	$	2,357
Reported as:
Current liabilities	$	1,254
Long-term liabilities	$	1,103

The Company has elected the transition option under Topic 842 and continued to apply the prior accounting standard for leases, including the disclosure requirements, in the comparative periods. As of December 31, 2018, future minimum rental payments under the non-cancelable operating leases were as follows (in thousands):

2019	$	1,511
2020		872
2021		273
2022		195
2023		26
Total	$	2,877

Rent expense for the years ended December 31, 2018 and 2017 was $1.8 million and $1.5 million, respectively.

Lessor

The Company owns certain office buildings and leases a portion of these properties to third parties under arrangements that are classified as operating leases. These leases have remaining lease terms from one year to five years. Some of these leases include options to renew the lease term for up to five years.

For the year ended  December 31, 2019, income related to lease payments was $1.8 million. As of  December 31, 2019, future income related to lease payments was as follows (in thousands):

2020	$	1,523
2021		1,378
2022		1,138
2023		604
2024		552
Thereafter		45
Total	$	5,240

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Note 3 - Cash, Cash Equivalents, Investments and Restricted Cash

12 Months Ended

Dec. 31, 2019

Notes to Financial Statements

Cash, Cash Equivalents, Investments, and Restricted Cash Disclosure [Text Block]

3.  CASH, CASH EQUIVALENTS, INVESTMENTS AND RESTRICTED CASH

The following is a summary of the Company’s cash, cash equivalents and investments (in thousands): 

	December 31,
	2019		2018
Cash, cash equivalents and investments:
Cash	$	144,860	$	131,569
Money market funds		28,100		41,135
Corporate debt securities		260,950		170,909
Commercial paper		1,994		-
U.S. treasuries and government agency bonds		19,493		32,068
Certificates of deposit		-		1,600
Auction-rate securities backed by student-loan notes		3,138		3,241
Total	$	458,535	$	380,522

	December 31,
	2019		2018
Reported as:
Cash and cash equivalents	$	172,960	$	172,704
Short-term investments		282,437		204,577
Long-term investments		3,138		3,241
Total	$	458,535	$	380,522

The contractual maturities of the Company’s short-term and long-term available-for-sale investments are as follows (in thousands):

	December 31,
	2019		2018
Due in less than 1 year	$	147,532	$	125,845
Due in 1 - 5 years		134,905		78,732
Due in greater than 5 years		3,138		3,241
Total	$	285,575	$	207,818

The following tables summarize the unrealized gain and loss positions related to the Company’s available-for sale investments (in thousands): 

	December 31, 2019
	Amortized Cost		Unrealized Gains		Unrealized Losses			Total Fair Value		Fair Value of Investments in Unrealized Loss Position
Money market funds	$	28,100	$	-	$	-		$	28,100	$	-
Corporate debt securities		260,645		383		(78	)		260,950		93,262
Commercial paper		1,994		-		-			1,994		-
U.S. treasuries and government agency bonds		19,487		7		(1	)		19,493		993
Auction-rate securities backed by student-loan notes		3,320		-		(182	)		3,138		3,138
Total	$	313,546	$	390	$	(261	)	$	313,675	$	97,393

	December 31, 2018
	Amortized Cost		Unrealized Gains		Unrealized Losses			Total Fair Value		Fair Value of Investments in Unrealized Loss Position
Money market funds	$	41,135	$	-	$	-		$	41,135	$	-
Corporate debt securities		172,288		7		(1,386	)		170,909		166,204
U.S. treasuries and government agency bonds		32,207		2		(141	)		32,068		28,507
Certificates of deposit		1,600		-		-			1,600		-
Auction-rate securities backed by student-loan notes		3,570		-		(329	)		3,241		3,241
Total	$	250,800	$	9	$	(1,856	)	$	248,953	$	197,952

As of  December 31, 2019 and 2018, unrealized losses that had been in a continuous loss position for 12 months or longer were $0.2 million and $1.6 million, respectively. The Company typically invests in highly rated securities, with the primary objective of minimizing the potential risk of principal loss. The Company’s investment policy generally requires securities to be investment grade and limits the amount of credit exposure to any one issuer. When evaluating a debt security for other-than-temporary impairment, management reviewed factors such as the Company’s intent to sell, or whether it will more likely than not be required to sell, the security before recovery of its amortized cost basis, the extent to which the fair value of the security is less than its cost, the financial condition of the issuer and the credit quality of the investment. As of  December 31, 2019 and 2018, the Company did not consider any of its available-for-sale investments to be other-than-temporarily impaired.

The Company redeemed $0.3 million and $2.0 million of its auction-rate securities at face value for the years ended December 31, 2019 and 2018, respectively. There were no sales of auction-rate securities for the year ended December 31, 2017. The underlying maturities of the remaining auction-rate securities are up to 27 years. As of December 31, 2019 and 2018, the impairment of $0.2 million and $0.3 million, respectively, was determined to be temporary because management possessed both the intent and ability to hold these securities for a period of time sufficient to allow for any anticipated recovery in fair value. In addition, management believed that it was more likely than not that the Company would not have to sell these securities before recovery of its amortized cost basis. All scheduled interest payments have been received on time pursuant to the terms and conditions of the securities. To date, the Company has redeemed $40.0 million, or 92% of the original portfolio in these auction-rate securities, at par without any realized losses.

Restricted Cash

The following table provides a reconciliation of cash, cash equivalents and restricted cash reported on the Consolidated Balance Sheets to the amounts reported on the Consolidated Statements of Cash Flows (in thousands): 

	December 31,
	2019		2018
Cash and cash equivalents	$	172,960	$	172,704
Restricted cash included in other long-term assets		116		114
Total cash, cash equivalents and restricted cash reported on the Consolidated Statements of Cash Flows	$	173,076	$	172,818

As of  December 31, 2019 and 2018, restricted cash included a security deposit that is set aside in a bank account and cannot be withdrawn by the Company under the terms of a lease agreement. The restriction will end upon the expiration of the lease.   

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Note 11 - Net Income Per Share (Tables)

12 Months Ended

Dec. 31, 2019

Notes Tables

Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]

	Year Ended December 31,
	2019		2018		2017
Numerator:
Net income	$	108,839	$	105,268	$	65,203
Denominator:
Weighted-average outstanding shares - basic		43,165		42,247		41,350
Effect of dilutive securities		2,598		2,355		2,228
Weighted-average outstanding shares - diluted		45,763		44,602		43,578
Net income per share:
Basic	$	2.52	$	2.49	$	1.58
Diluted	$	2.38	$	2.36	$	1.50

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Note 3 - Cash, Cash Equivalents, Investments and Restricted Cash (Tables)

12 Months Ended

Dec. 31, 2019

Notes Tables

Fair Value, by Balance Sheet Grouping [Table Text Block]

	December 31,
	2019		2018
Cash, cash equivalents and investments:
Cash	$	144,860	$	131,569
Money market funds		28,100		41,135
Corporate debt securities		260,950		170,909
Commercial paper		1,994		-
U.S. treasuries and government agency bonds		19,493		32,068
Certificates of deposit		-		1,600
Auction-rate securities backed by student-loan notes		3,138		3,241
Total	$	458,535	$	380,522

	December 31,
	2019		2018
Reported as:
Cash and cash equivalents	$	172,960	$	172,704
Short-term investments		282,437		204,577
Long-term investments		3,138		3,241
Total	$	458,535	$	380,522

Investments Classified by Contractual Maturity Date [Table Text Block]

	December 31,
	2019		2018
Due in less than 1 year	$	147,532	$	125,845
Due in 1 - 5 years		134,905		78,732
Due in greater than 5 years		3,138		3,241
Total	$	285,575	$	207,818

Unrealized Gain (Loss) on Investments [Table Text Block]

	December 31, 2019
	Amortized Cost		Unrealized Gains		Unrealized Losses			Total Fair Value		Fair Value of Investments in Unrealized Loss Position
Money market funds	$	28,100	$	-	$	-		$	28,100	$	-
Corporate debt securities		260,645		383		(78	)		260,950		93,262
Commercial paper		1,994		-		-			1,994		-
U.S. treasuries and government agency bonds		19,487		7		(1	)		19,493		993
Auction-rate securities backed by student-loan notes		3,320		-		(182	)		3,138		3,138
Total	$	313,546	$	390	$	(261	)	$	313,675	$	97,393

	December 31, 2018
	Amortized Cost		Unrealized Gains		Unrealized Losses			Total Fair Value		Fair Value of Investments in Unrealized Loss Position
Money market funds	$	41,135	$	-	$	-		$	41,135	$	-
Corporate debt securities		172,288		7		(1,386	)		170,909		166,204
U.S. treasuries and government agency bonds		32,207		2		(141	)		32,068		28,507
Certificates of deposit		1,600		-		-			1,600		-
Auction-rate securities backed by student-loan notes		3,570		-		(329	)		3,241		3,241
Total	$	250,800	$	9	$	(1,856	)	$	248,953	$	197,952

Restrictions on Cash and Cash Equivalents [Table Text Block]

	December 31,
	2019		2018
Cash and cash equivalents	$	172,960	$	172,704
Restricted cash included in other long-term assets		116		114
Total cash, cash equivalents and restricted cash reported on the Consolidated Statements of Cash Flows	$	173,076	$	172,818

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Note 7 - Leases (Tables)

12 Months Ended

Dec. 31, 2019

Notes Tables

Lease, Cost [Table Text Block]

	Year Ended
	December 31, 2019
Lease costs:
Operating lease costs	$	1,509
Short-term and other lease costs		465
Total lease costs	$	1,974

	Year Ended
	December 31, 2019
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$	1,364
ROU assets obtained in exchange for new operating lease liabilities (1)	$	3,667

	December 31, 2019
Weighted-average remaining lease term (in years)		2.1
Weighted-average discount rate		3.7	%

Lessee, Operating Lease, Liability, Maturity [Table Text Block]

2020	$	1,328
2021		734
2022		390
2023		22
Total remaining lease payments		2,474
Less: imputed interest		(117	)
Total lease liabilities	$	2,357
Reported as:
Current liabilities	$	1,254
Long-term liabilities	$	1,103

Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block]

2019	$	1,511
2020		872
2021		273
2022		195
2023		26
Total	$	2,877

Lessor, Operating Lease, Payments to be Received, Maturity [Table Text Block]

2020	$	1,523
2021		1,378
2022		1,138
2023		604
2024		552
Thereafter		45
Total	$	5,240

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Note 17 - Accumulated Other Comprehensive Loss

12 Months Ended

Dec. 31, 2019

Notes to Financial Statements

Comprehensive Income (Loss) Note [Text Block]

17. ACCUMULATED OTHER COMPREHENSIVE LOSS

The following table summarizes the changes in accumulated other comprehensive loss (in thousands):

	Unrealized Gains (Losses) on Available-for-Sale Securities			Foreign Currency Translation Adjustments			Total
Balance as of January 1, 2018	$	(1,364	)	$	3,177		$	1,813
Other comprehensive loss before reclassifications		(549	)		(7,082	)		(7,631	)
Amounts reclassified from accumulated other comprehensive income (loss)		66			-			66
Tax effect		209			-			209
Net current period other comprehensive loss		(274	)		(7,082	)		(7,356	)
Balance as of December 31, 2018		(1,638	)		(3,905	)		(5,543	)
Other comprehensive income (loss) before reclassifications		1,977			(1,706	)		271
Amounts reclassified from accumulated other comprehensive loss		(1	)		-			(1	)
Tax effect		(203	)		-			(203	)
Net current period other comprehensive income (loss)		1,773			(1,706	)		67
Balance as of December 31, 2019	$	135		$	(5,611	)	$	(5,476	)

The amounts reclassified from accumulated other comprehensive income (loss) were recorded in interest and other income, net, in the Consolidated Statements of Operations.  For the year ended December 31, 2019, the Company did not elect to reclassify the income tax effects of the 2017 Tax Act from accumulated other comprehensive loss to retained earnings as the amounts were not material.  

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Note 13 - Commitments and Contingencies

12 Months Ended

Dec. 31, 2019

Notes to Financial Statements

Commitments and Contingencies Disclosure [Text Block]

13.  COMMITMENTS AND CONTINGENCIES

Warranty and Indemnification Provisions

The changes in warranty reserves are as follows (in thousands):

	Year Ended December 31,
	2019			2018			2017
Balance at beginning of period	$	4,564		$	2,416		$	1,030
Warranty provision for product sales		891			6,586			1,912
Settlements made		(2,768	)		(1,402	)		(40	)
Unused warranty provision		(1,548	)		(3,036	)		(486	)
Balance at end of period	$	1,139		$	4,564		$	2,416

The Company provides indemnification agreements to certain direct or indirect customers. The Company agrees to reimburse these parties for any damages, costs and expenses incurred by them as a result of legal actions taken against them by third parties for infringing upon their intellectual property rights as a result of using the Company’s products and technologies. These indemnification provisions are varied in their scope and are subject to certain terms, conditions, limitations and exclusions. In addition, the Company has entered into indemnification agreements with its directors and officers.

It is not possible to predict the maximum potential amount of future payments under these agreements due to the limited history of indemnification claims and the unique facts and circumstances involved in each particular agreement. There were no indemnification liabilities incurred in any of the periods presented. However, there can be no assurances that the Company will not incur any financial liabilities in the future as a result of these obligations.

Purchase Commitments

The Company has outstanding purchase commitments with its suppliers and other parties that require the future purchases of goods or services, which primarily consist of wafer and other inventory purchases, assembly and other manufacturing services, construction or purchases of property and equipment, and license arrangements. As of  December 31, 2019, the Company’s outstanding purchase obligations totaled approximately $90.6 million.

Litigation

The Company is a party to actions and proceedings in the ordinary course of business, including potential litigation initiated by its stockholders, challenges to the enforceability or validity of its intellectual property, claims that the Company’s products infringe on the intellectual property rights of others, and employment matters. These proceedings often involve complex questions of fact and law and  may require the expenditure of significant funds and the diversion of other resources to prosecute and defend. The Company defends itself vigorously against any such claims. As of  December 31, 2019, there were no material pending legal proceedings to which the Company was a party.

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Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Common Stock Including Additional Paid in Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Total
Balance (in shares) at Dec. 31, 2016	40,793
Balance at Dec. 31, 2016	$ 315,969	$ 119,362	$ (4,215)	$ 431,116
Net income	0	65,203	0	65,203
Other comprehensive income (loss)	0	0	6,028	6,028
Dividends and dividend equivalents declared	$ 0	(35,816)	0	(35,816)
Common stock issued under the employee equity incentive plan (in shares)	781
Common stock issued under the employee equity incentive plan	$ 150	0	0	150
Common stock issued under the employee stock purchase plan (in shares)	40
Common stock issued under the employee stock purchase plan	$ 2,701	0	0	2,701
Stock-based compensation expense	52,625	0	0	52,625
Cumulative effect of a change in accounting principles at Dec. 31, 2017	$ 5,141	(5,141)	0	0
Balance (in shares) at Dec. 31, 2017	41,614
Balance at Dec. 31, 2017	$ 376,586	143,608	1,813	522,007
Net income	0	105,268	0	105,268
Other comprehensive income (loss)	0	0	(7,356)	(7,356)
Dividends and dividend equivalents declared	$ 0	(54,527)	0	(54,527)
Common stock issued under the employee equity incentive plan (in shares)	858
Common stock issued under the employee equity incentive plan	$ 10,637	0	0	10,637
Common stock issued under the employee stock purchase plan (in shares)	33
Common stock issued under the employee stock purchase plan	$ 3,028	0	0	3,028
Stock-based compensation expense	60,657	0	0	60,657
Cumulative effect of a change in accounting principles at Dec. 31, 2018	$ 0	379	0	$ 379
Balance (in shares) at Dec. 31, 2018	42,505			42,505
Balance at Dec. 31, 2018	$ 450,908	194,728	(5,543)	$ 640,093
Net income	0	108,839	0	108,839
Other comprehensive income (loss)	0	0	67	67
Dividends and dividend equivalents declared	$ 0	(74,117)	0	(74,117)
Common stock issued under the employee equity incentive plan (in shares)	1,083
Common stock issued under the employee equity incentive plan	$ 16,650	0	0	16,650
Common stock issued under the employee stock purchase plan (in shares)	28
Common stock issued under the employee stock purchase plan	$ 3,277	0	0	3,277
Stock-based compensation expense	$ 78,682	0	0	$ 78,682
Balance (in shares) at Dec. 31, 2019	43,616			43,616
Balance at Dec. 31, 2019	$ 549,517	$ 229,450	$ (5,476)	$ 773,491

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Consolidated Balance Sheets (Parentheticals) - $ / shares shares in Thousands	Dec. 31, 2019	Dec. 31, 2018
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	150,000	150,000
Common stock, shares issued (in shares)	43,616	42,505
Common stock, shares outstanding (in shares)	43,616	42,505

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Note 7 - Leases - Maturities of Lease Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
2020	$ 1,328
2021	734
2022	390
2023	22
Total remaining lease payments	2,474
Less: imputed interest	(117)
Accrued Liabilities and Other Long-term Liabilities [Member]
Total lease liabilities	2,357
Accrued Liabilities, Current [Member]
Current liabilities	1,254	$ 0
Other Long-term Liabilities [Member]
Long-term liabilities	$ 1,103	$ 0

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Note 17 - Accumulated Other Comprehensive Loss - Changes in Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Balance	$ 640,093	$ 522,007
Balance	773,491	640,093
AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Parent [Member]
Balance	(1,638)	(1,364)
Other comprehensive income (loss) before reclassifications	1,977	(549)
Amounts reclassified from accumulated other comprehensive income (loss)	(1)	66
Tax effect	(203)	209
Net current period other comprehensive income (loss)	1,773	(274)
Balance	135	(1,638)
Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
Balance	(3,905)	3,177
Other comprehensive income (loss) before reclassifications	(1,706)	(7,082)
Amounts reclassified from accumulated other comprehensive income (loss)	0	0
Tax effect	0	0
Net current period other comprehensive income (loss)	(1,706)	(7,082)
Balance	(5,611)	(3,905)
AOCI Attributable to Parent [Member]
Balance	(5,543)	1,813
Other comprehensive income (loss) before reclassifications	271	(7,631)
Amounts reclassified from accumulated other comprehensive income (loss)	(1)	66
Tax effect	(203)	209
Net current period other comprehensive income (loss)	67	(7,356)
Balance	$ (5,476)	$ (5,543)

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Note 6 - Real Estate Transaction (Details Textual) $ in Millions	1 Months Ended
	Mar. 31, 2019 USD ($)
Payments to Acquire Real Estate, Total	$ 52.9
Real Estate, Capitalized Transaction Costs	$ 0.4
Leases, Acquired-in-Place [Member]
Finite-Lived Intangible Asset, Useful Life	3 years 6 months
Building [Member]
Property, Plant and Equipment, Useful Life	40 years

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Note 5 - Balance Sheet Components - Property and Equipment, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Property and equipment	$ 347,246	$ 259,548
Less: accumulated depreciation and amortization	(118,931)	(109,547)
Property and equipment, net	228,315	150,001
Production Equipment and Software [Member]
Property and equipment	134,420	120,645
Building and Building Improvements [Member]
Property and equipment	149,443	100,135
Land [Member]
Property and equipment	35,040	16,724
Transportation Equipment [Member]
Property and equipment	16,510	12,948
Leasehold Improvements [Member]
Property and equipment	7,173	4,755
Furniture and Fixtures [Member]
Property and equipment	$ 4,660	$ 4,341

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Note 16 - Segment and Geographic Information (Details Textual)	12 Months Ended
	Dec. 31, 2019
Number of Reportable Segments	1

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Note 16 - Segment and Geographic Information (Tables)

12 Months Ended

Dec. 31, 2019

Notes Tables

Schedule of Revenue from External Customers Attributed to Foreign Countries by Geographic Area [Table Text Block]

	Year Ended December 31,
Country or Region	2019		2018		2017
China	$	382,740	$	334,726	$	257,787
Taiwan		73,801		75,307		83,357
Europe		49,467		49,484		38,140
Korea		43,900		41,238		34,155
Southeast Asia		32,031		36,495		25,755
Japan		27,812		26,853		20,187
United States		17,836		17,621		11,113
Other		334		658		435
Total	$	627,921	$	582,382	$	470,929

Revenue from External Customers by Products and Services [Table Text Block]

	Year Ended December 31,
Product Family	2019		2018		2017
DC to DC	$	589,651	$	537,512	$	431,861
Lighting Control		38,270		44,870		39,068
Total	$	627,921	$	582,382	$	470,929

Schedule of Disclosure on Geographic Areas, Long-Lived Assets in Individual Foreign Countries by Country [Table Text Block]

	December 31,
Country	2019		2018		2017
China	$	113,888	$	93,096	$	89,472
United States		94,671		39,054		37,539
Taiwan		17,652		16,972		17,238
Other		2,104		879		387
Total	$	228,315	$	150,001	$	144,636

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Note 1 - Summary of Significant Accounting Policies - Summary of Deferred Compensation Plan (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred compensation plan assets	$ 38,858	$ 31,970
Deferred compensation plan liabilities	40,090	32,730
Other Long-term Assets [Member]
Deferred compensation plan assets	38,858	31,970
Accrued Compensation and Related Benefits [Member]
Deferred compensation plan liabilities	425	447
Other Long-term Liabilities [Member]
Deferred compensation plan liabilities	39,665	32,283
Cash Surrender Value [Member]
Deferred compensation plan assets	16,883	13,103
Mutual Funds and Money Market Funds, Fair Value [Member]
Deferred compensation plan assets	$ 21,975	$ 18,867

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Note 12 - Income Taxes - Components of Income Before Income Tax (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
United States									$ (4,134)	$ (13,151)	$ (19,115)
Foreign									117,254	131,633	102,059
Income before income taxes	$ 33,425	$ 32,289	$ 22,348	$ 25,058	$ 32,684	$ 36,207	$ 27,114	$ 22,477	$ 113,120	$ 118,482	$ 82,944

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Note 8 - Stock-based Compensation (Details Textual) $ / shares in Units, $ in Thousands	1 Months Ended						12 Months Ended
	Feb. 28, 2019 USD ($) $ / shares shares	Oct. 31, 2018 USD ($) $ / shares shares	Feb. 28, 2018 USD ($) $ / shares shares	Feb. 28, 2017 USD ($) $ / shares shares	Dec. 31, 2015 $ / shares shares	Dec. 31, 2013 USD ($) $ / shares shares	Dec. 31, 2019 USD ($) $ / shares shares	Dec. 31, 2018 USD ($) shares	Dec. 31, 2017 USD ($) shares	Dec. 31, 2015 USD ($) $ / shares shares	Nov. 13, 2014 shares
Proceeds, Issuance of Shares, Share-based Payment Arrangement, Excluding Option Exercised | $							$ 16,650	$ 10,637	$ 150
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period							564,000	1,363,000	666,000
Proceeds from Stock Plans | $							$ 3,277	$ 3,028	$ 2,701
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Aggregate Intrinsic Value, Vested | $							138,300	90,000	74,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Aggregate Intrinsic Value, Outstanding | $							$ 679,500
Share Price | $ / shares							$ 178.02
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total | $							$ 100,100
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition							3 years
Proceeds, Issuance of Shares, Share-based Payment Arrangement, Excluding Option Exercised | $							$ 16,600	$ 10,600	$ 0
Time-Based RSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period							52,000	133,000	81,000
Time-Based RSUs [Member] | Employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period							4 years
Time-Based RSUs [Member] | Director [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period							1 year
PSU 2019 [Member]
Share Price | $ / shares	$ 130.67	$ 108.43
Share-based Compensation Arrangement by Share-based Payment Award, Price Per Share Payable Upon Vesting of Equity Instruments Other than Options | $ / shares	$ 30
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term	2 years 7 months 6 days	2 years 10 months 24 days
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate	29.00%	28.70%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate	2.50%	2.90%
PSU 2019 [Member] | Executive Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	151,000
Share-based Compensation Arrangement by Share-based Payment Award, Vesting, Measurement Period of Relative Revenue Growth Rate to Industry Average	2 years
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Maximum Percentage Allowed	300.00%
Maximum Stock Compensation Costs | $	$ 46,600
PSU 2019 [Member] | Executive Officer [Member] | Vesting First Quarter of 2021 if Performance Conditions are Met [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage	50.00%
PSU 2019 [Member] | Executive Officer [Member] | Vesting Over Two Years Following First Quarter of 2021 on Quarterly Basis [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage	50.00%
PSU 2019 [Member] | Non-Executive Employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period		53,000
Share-based Compensation Arrangement by Share-based Payment Award, Vesting, Measurement Period of Relative Revenue Growth Rate to Industry Average		2 years
Maximum Stock Compensation Costs | $		$ 10,900
Share-based Compensation Arrangement by Share-based Payment Award, Price Per Share Payable Upon Vesting of Equity Instruments Other than Options | $ / shares		$ 30
PSU 2019 [Member] | Non-Executive Employees [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Minimum Percentage Allowed		200.00%
PSU 2019 [Member] | Non-Executive Employees [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Maximum Percentage Allowed		300.00%
PSU 2019 [Member] | Non-Executive Employees [Member] | Vesting First Quarter of 2021 if Performance Conditions are Met [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage		50.00%
PSU 2019 [Member] | Non-Executive Employees [Member] | Vesting Over Two Years Following First Quarter of 2021 on an Annual or Quarterly Basis [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage		50.00%
PSU 2018 [Member]
Share Price | $ / shares			$ 110.00
Share-based Compensation Arrangement by Share-based Payment Award, Price Per Share Payable Upon Vesting of Equity Instruments Other than Options | $ / shares			$ 30
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term			2 years 7 months 6 days
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate			27.50%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate			2.30%
PSU 2018 [Member] | Executive Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period			188,000
Share-based Compensation Arrangement by Share-based Payment Award, Vesting, Measurement Period of Relative Revenue Growth Rate to Industry Average			2 years
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Maximum Percentage Allowed			300.00%
Maximum Stock Compensation Costs | $			$ 46,100
PSU 2018 [Member] | Executive Officer [Member] | Vesting First Quarter of 2020 if Performance Conditions are Met [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage			50.00%
PSU 2018 [Member] | Executive Officer [Member] | Vesting Over Two Years Following First Quarter of 2020 on Quarterly or Annual Basis [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage			50.00%
PSU 2018 [Member] | Non-Executive Employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period			44,000
Share-based Compensation Arrangement by Share-based Payment Award, Vesting, Measurement Period of Relative Revenue Growth Rate to Industry Average			2 years
Maximum Stock Compensation Costs | $			$ 8,800
PSU 2018 [Member] | Non-Executive Employees [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Minimum Percentage Allowed			200.00%
PSU 2018 [Member] | Non-Executive Employees [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Maximum Percentage Allowed			300.00%
PSU 2018 [Member] | Non-Executive Employees [Member] | Vesting First Quarter of 2020 if Performance Conditions are Met [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage			50.00%
PSU 2018 [Member] | Non-Executive Employees [Member] | Vesting Over Two Years Following First Quarter of 2020 on an Annual or Quarterly Basis [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage			50.00%
2017 PSU's [Member]
Share Price | $ / shares				$ 89.37
Share-based Compensation Arrangement by Share-based Payment Award, Price Per Share Payable Upon Vesting of Equity Instruments Other than Options | $ / shares				$ 30
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term				2 years 7 months 6 days
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate				28.60%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate				1.30%
2017 PSU's [Member] | Executive Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period				200,000
Share-based Compensation Arrangement by Share-based Payment Award, Vesting, Measurement Period of Relative Revenue Growth Rate to Industry Average				2 years
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Maximum Percentage Allowed				300.00%
Maximum Stock Compensation Costs | $				$ 31,500
Total PSU Earned	521,000
2017 PSU's [Member] | Executive Officer [Member] | Vested First Quarter of 2019 [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage				50.00%
2017 PSU's [Member] | Executive Officer [Member] | Vesting Over Two Years Following First Quarter of 2019 on Quarterly Basis [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage				50.00%
2017 PSU's [Member] | Non-Executive Employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period				48,000
Share-based Compensation Arrangement by Share-based Payment Award, Vesting, Measurement Period of Relative Revenue Growth Rate to Industry Average				2 years
Maximum Stock Compensation Costs | $				$ 6,100
Total PSU Earned	101,000
2017 PSU's [Member] | Non-Executive Employees [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Minimum Percentage Allowed				200.00%
2017 PSU's [Member] | Non-Executive Employees [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Maximum Percentage Allowed				300.00%
2017 PSU's [Member] | Non-Executive Employees [Member] | Vested First Quarter of 2019 [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage				50.00%
2017 PSU's [Member] | Non-Executive Employees [Member] | Vesting Over Two Years Following First Quarter of 2019 on an Annual or Quarterly Basis [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage				50.00%
2015 MPSUs [Member]
Share Price | $ / shares					$ 61.35					$ 61.35
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Maximum Percentage Allowed					500.00%
Maximum Stock Compensation Costs | $										$ 24,600
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate										33.20%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate										1.30%
Number of MPSU Tranches					4
Total MSUs Earned							600,000
Share-based Compensation Arrangement by Share-based Payment Award, Post-Award Vesting Period, Restriction Period on Sales					2 years
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Discount for Postvesting Restrictions										7.80%
2015 MPSUs [Member] | Share-based Payment Arrangement, Tranche One [Member]
Maximum Stock Compensation Costs | $										$ 8,300
Share-based Compensation Arrangement by Share-based Payment Award, Number of Price Targets					5
2015 MPSUs [Member] | Share-based Payment Arrangement, Tranche One [Member] | Minimum [Member]
Market Awards Price Targets | $ / shares					$ 71.36
2015 MPSUs [Member] | Share-based Payment Arrangement, Tranche One [Member] | Maximum [Member]
Market Awards Price Targets | $ / shares					$ 95.57
2015 MPSUs [Member] | Second, Third, and Fourth Tranches [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Price Targets					5
Total number of performance conditions					6
2015 MPSUs [Member] | Share-based Payment Arrangement, Tranche Two [Member]
Maximum Stock Compensation Costs | $										4,500
2015 MPSUs [Member] | Share-based Payment Arrangement, Tranche Two [Member] | Minimum [Member]
Market Awards Price Targets | $ / shares					$ 89.56
2015 MPSUs [Member] | Share-based Payment Arrangement, Tranche Two [Member] | Maximum [Member]
Market Awards Price Targets | $ / shares					106.81
2015 MPSUs [Member] | Share-based Payment Arrangement, Tranche Three [Member]
Maximum Stock Compensation Costs | $										5,200
2015 MPSUs [Member] | Share-based Payment Arrangement, Tranche Three [Member] | Minimum [Member]
Market Awards Price Targets | $ / shares					120.80
2015 MPSUs [Member] | Share-based Payment Arrangement, Tranche Three [Member] | Maximum [Member]
Market Awards Price Targets | $ / shares					135.48
2015 MPSUs [Member] | Share-based Compensation Award, Tranche Four [Member]
Maximum Stock Compensation Costs | $										$ 6,600
2015 MPSUs [Member] | Share-based Compensation Award, Tranche Four [Member] | Minimum [Member]
Market Awards Price Targets | $ / shares					126.08
2015 MPSUs [Member] | Share-based Compensation Award, Tranche Four [Member] | Maximum [Member]
Market Awards Price Targets | $ / shares					$ 136.79
2015 MPSUs [Member] | Executive Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period					86,000
2015 MPSUs [Member] | Non-Executive Employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period					41,000
MSUs 2018 [Member]
Share Price | $ / shares		$ 108.43
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Maximum Percentage Allowed		500.00%
Maximum Stock Compensation Costs | $		$ 40,400
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate		31.60%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate		3.00%
Share-based Compensation Arrangement by Share-based Payment Award, Number of Price Targets		5
Total MSUs Earned							600,000
Share-based Compensation Arrangement by Share-based Payment Award, Post-Award Vesting Period, Restriction Period on Sales		2 years
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Discount for Postvesting Restrictions		8.70%
MSUs 2018 [Member] | Minimum [Member]
Market Awards Price Targets | $ / shares		$ 140
MSUs 2018 [Member] | Maximum [Member]
Market Awards Price Targets | $ / shares		$ 172
MSUs 2018 [Member] | Executive Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period		60,000
MSUs 2018 [Member] | Non-Executive Employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period		60,000
2013 MSU's [Member]
Share Price | $ / shares						$ 31.73
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Maximum Percentage Allowed						500.00%
Maximum Stock Compensation Costs | $						$ 38,200
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate						38.70%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate						1.60%
Share-based Compensation Arrangement by Share-based Payment Award, Number of Price Targets						5
Total MSUs Earned										1,800,000
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Discount for Postvesting Restrictions						0.00%
2013 MSU's [Member] | Minimum [Member]
Market Awards Price Targets | $ / shares						$ 40
2013 MSU's [Member] | Maximum [Member]
Market Awards Price Targets | $ / shares						$ 56
2013 MSU's [Member] | Executive Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period						276,000
2013 MSU's [Member] | Non-Executive Employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period						84,000
The2014 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized											5,500,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant							1,600,000
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant							4,500,000
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total | $							$ 100
Share-based Compensation Arrangement by Share-based Payment Award, Maximum Number of Shares Per Employee							2,000
Share-based Compensation Arrangement by Share-based Payment Award, Maximum Number of Shares per Employee Value							25,000
Share-based Compensation Arrangement by Share-based Payment Award, Automatic Increase Shares							1,000,000
Share-basedCompensation Arrangement by Share-based Payment Award, Other Than Options, Percent Increases in Period							2.00%
Stock Issued During Period, Shares, Employee Stock Purchase Plans							28,000	33,000	40,000
Employee Stock Purchase Plan Shares Issued, Intrinsic Value | $							$ 700	$ 1,100	$ 1,000
Proceeds from Stock Plans | $							$ 3,300	$ 3,000	$ 2,700

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Note 9 - Dividends and Dividend Equivalents (Details Textual) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Dividends Payable, Current	$ 17.4	$ 12.8
Accrued Dividend Equivalents	$ 10.6	$ 8.4

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Note 12 - Income Taxes - Unrecognized Tax Benefits Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Balance	$ 20,491	$ 16,272	$ 14,431
Increase for tax position of prior year	1,589	1,474	169
Increase for tax position of current year	4,663	2,957	2,360
Decrease due to lapse of statute of limitation	(776)	(212)	(688)
Decrease due to settlement with tax authorities	(560)
Balance	$ 25,407	$ 20,491	$ 16,272

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Note 15 - Significant Customers - Customers Concentration Summary (Details) - Customer Concentration Risk [Member]	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Distributor A [Member] | Revenue Benchmark [Member]
Concentration risk	23.00%	22.00%	17.00%
Distributor A [Member] | Accounts Receivable [Member]
Concentration risk	24.00%	25.00%
Distributor B [Member] | Revenue Benchmark [Member]
Concentration risk		10.00%
Distributor B [Member] | Accounts Receivable [Member]
Concentration risk	11.00%	16.00%
Distributor C [Member] | Revenue Benchmark [Member]
Concentration risk			10.00%
Value Added Reseller A [Member] | Accounts Receivable [Member]
Concentration risk	13.00%

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Note 11 - Net Income Per Share - Net Income Per Share Basic and Diluted (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Numerator:
Net income	$ 32,436	$ 29,528	$ 20,693	$ 26,181	$ 27,638	$ 31,568	$ 24,206	$ 21,856	$ 108,839	$ 105,268	$ 65,203
Denominator:
Weighted-average outstanding shares - basic (in shares)									43,165	42,247	41,350
Effect of dilutive securities (in shares)									2,598	2,355	2,228
Weighted-average outstanding shares - diluted (in shares)	46,503	45,833	45,483	45,232	45,058	44,669	44,400	44,282	45,763	44,602	43,578
Net income per share:
Earnings per share, basic (in dollars per share)	$ 0.75	$ 0.68	$ 0.48	$ 0.61	$ 0.65	$ 0.75	$ 0.57	$ 0.52	$ 2.52	$ 2.49	$ 1.58
Earnings per share, diluted (in dollars per share)	$ 0.70	$ 0.64	$ 0.45	$ 0.58	$ 0.61	$ 0.71	$ 0.55	$ 0.49	$ 2.38	$ 2.36	$ 1.50

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Note 4 - Fair Value Measurements - Discounted Cash Flow Assumptions (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Minimum [Member]
Time-to-liquidity (Year)	2 years	2 years
Discount rate	4.00%	4.90%
Maximum [Member]
Time-to-liquidity (Year)	3 years	3 years
Discount rate	8.30%	10.10%

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Note 3 - Cash, Cash Equivalents, Investments and Restricted Cash - Unrealized Gains and Losses on Investments (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Amortized Cost	$ 313,546	$ 250,800
Unrealized Gains	390	9
Unrealized Losses	(261)	(1,856)
Total Fair Value	313,675	248,953
Fair Value of Investments in Unrealized Loss Position	97,393	197,952
Money Market Funds [Member]
Amortized Cost	28,100	41,135
Unrealized Gains	0	0
Unrealized Losses	0	0
Total Fair Value	28,100	41,135
Fair Value of Investments in Unrealized Loss Position	0	0
Corporate Debt Securities [Member]
Amortized Cost	260,645	172,288
Unrealized Gains	383	7
Unrealized Losses	(78)	(1,386)
Total Fair Value	260,950	170,909
Fair Value of Investments in Unrealized Loss Position	93,262	166,204
Commercial Paper [Member]
Amortized Cost	1,994
Unrealized Gains	0
Unrealized Losses	0
Total Fair Value	1,994
Fair Value of Investments in Unrealized Loss Position	0
US Government Agencies Short-term Debt Securities [Member]
Amortized Cost	19,487	32,207
Unrealized Gains	7	2
Unrealized Losses	(1)	(141)
Total Fair Value	19,493	32,068
Fair Value of Investments in Unrealized Loss Position	993	28,507
Certificates of Deposit [Member]
Amortized Cost		1,600
Unrealized Gains		0
Unrealized Losses		0
Total Fair Value		1,600
Fair Value of Investments in Unrealized Loss Position		0
Auction Rate Securities [Member]
Amortized Cost	3,320	3,570
Unrealized Gains	0	0
Unrealized Losses	(182)	(329)
Total Fair Value	3,138	3,241
Fair Value of Investments in Unrealized Loss Position	$ 3,138	$ 3,241

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Note 5 - Balance Sheet Components (Tables)

12 Months Ended

Dec. 31, 2019

Notes Tables

Schedule of Inventory, Current [Table Text Block]

	December 31,
	2019		2018
Raw materials	$	22,872	$	43,017
Work in process		42,681		38,674
Finished goods		61,947		54,693
Total	$	127,500	$	136,384

Schedule of Other Current Assets [Table Text Block]

	December 31,
	2019		2018
RSU tax withholding proceeds receivable	$	6,106	$	39
Prepaid expense		7,991		3,425
Interest receivable		2,490		1,441
Assets for product returns		1,585		1,602
Prepaid wafer refund receivable		-		4,297
Other		1,433		1,127
Total	$	19,605	$	11,931

Property, Plant and Equipment [Table Text Block]

	December 31,
	2019			2018
Production equipment and software	$	134,420		$	120,645
Buildings and improvements		149,443			100,135
Land		35,040			16,724
Transportation equipment		16,510			12,948
Leasehold improvements		7,173			4,755
Furniture and fixtures		4,660			4,341
Property and equipment		347,246			259,548
Less: accumulated depreciation and amortization		(118,931	)		(109,547	)
Property and equipment, net	$	228,315		$	150,001

Schedule of Other Assets, Noncurrent [Table Text Block]

	December 31,
	2019		2018
Deferred compensation plan assets	$	38,858	$	31,970
Operating lease ROU assets		2,863		-
Prepaid expense		2,687		2,713
Other		1,544		1,296
Total	$	45,952	$	35,979

Schedule of Accrued Liabilities [Table Text Block]

	December 31,
	2019		2018
Dividends and dividend equivalents	$	21,747	$	15,044
Stock rotation and sales returns		5,530		5,363
Customer prepayments		3,412		2,520
Income tax payable		2,435		7,018
Commissions		1,425		1,369
Operating lease liabilities		1,254		-
Warranty		1,139		4,564
Other		7,848		3,084
Total	$	44,790	$	38,962

Other Noncurrent Liabilities [Table Text Block]

	December 31,
	2019		2018
Deferred compensation plan liabilities	$	39,665	$	32,283
Dividend equivalents		6,265		6,145
Operating lease liabilities		1,103		-
Other		30		97
Total	$	47,063	$	38,525

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Note 9 - Dividends and Dividend Equivalents (Tables)

12 Months Ended

Dec. 31, 2019

Notes Tables

Dividends Declared [Table Text Block]

	Year Ended December 31,
	2019		2018		2017
Dividend declared per share	$	1.60	$	1.20	$	0.80
Total amount	$	69,196	$	50,803	$	33,145

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Note 9 - Dividends and Dividend Equivalents

12 Months Ended

Dec. 31, 2019

Notes to Financial Statements

Dividends And Dividend Equivalents [Text Block]

9. DIVIDENDS AND DIVIDEND EQUIVALENTS

Cash Dividend Program

The Company has a dividend program approved by the Board of Directors, pursuant to which the Company intends to pay quarterly cash dividends on its common stock. Based on the Company’s historical practice, stockholders of record as of the last business day of the quarter are entitled to receive the quarterly cash dividends when and if declared by the Board of Directors, which are payable to the stockholders in the following month. The Board of Directors declared the following cash dividends (in thousands, except per-share amounts):   

	Year Ended December 31,
	2019		2018		2017
Dividend declared per share	$	1.60	$	1.20	$	0.80
Total amount	$	69,196	$	50,803	$	33,145

As of  December 31, 2019 and 2018, accrued dividends totaled $17.4 million and $12.8 million, respectively.

The declaration of any future cash dividends is at the discretion of the Board of Directors and will depend on, among other things, the Company’s financial condition, results of operations, capital requirements, business conditions, and other factors that the Board of Directors  may deem relevant, as well as a determination that cash dividends are in the best interests of the stockholders.

The Company anticipates that cash used for future dividend payments will come from its domestic cash, cash generated from ongoing U.S. operations, and cash repatriated from its Bermuda subsidiary. Earnings from other foreign subsidiaries will continue to be indefinitely reinvested.

Cash Dividend Equivalent Rights

The Company's RSUs contain rights to receive cash dividend equivalents, which entitle employees who hold RSUs to the same dividend value per share as holders of common stock. The dividend equivalents are accumulated and paid to the employees when the underlying RSUs vest. Dividend equivalents accumulated on the underlying RSUs are forfeited if the employees do not fulfill the requisite service requirement and, as a result, the awards do not vest. As of  December 31, 2019 and 2018, accrued dividend equivalents totaled $10.6 million and $8.4 million, respectively.   

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Note 5 - Balance Sheet Components

12 Months Ended

Dec. 31, 2019

Notes to Financial Statements

Supplemental Balance Sheet Disclosures [Text Block]

5. BALANCE SHEET COMPONENTS

Inventories 

Inventories consist of the following (in thousands):

	December 31,
	2019		2018
Raw materials	$	22,872	$	43,017
Work in process		42,681		38,674
Finished goods		61,947		54,693
Total	$	127,500	$	136,384

Other Current Assets

Other current assets consist of the following (in thousands):

	December 31,
	2019		2018
RSU tax withholding proceeds receivable	$	6,106	$	39
Prepaid expense		7,991		3,425
Interest receivable		2,490		1,441
Assets for product returns		1,585		1,602
Prepaid wafer refund receivable		-		4,297
Other		1,433		1,127
Total	$	19,605	$	11,931

Property and Equipment, Net

Property and equipment, net, consist of the following (in thousands):

	December 31,
	2019			2018
Production equipment and software	$	134,420		$	120,645
Buildings and improvements		149,443			100,135
Land		35,040			16,724
Transportation equipment		16,510			12,948
Leasehold improvements		7,173			4,755
Furniture and fixtures		4,660			4,341
Property and equipment		347,246			259,548
Less: accumulated depreciation and amortization		(118,931	)		(109,547	)
Property and equipment, net	$	228,315		$	150,001

Depreciation and amortization expense on property and equipment was $14.5 million, $11.4 million and $14.0 million for the years ended December 31, 2019, 2018 and 2017, respectively.

Other Long-Term Assets

Other long-term assets consist of the following (in thousands):

	December 31,
	2019		2018
Deferred compensation plan assets	$	38,858	$	31,970
Operating lease ROU assets		2,863		-
Prepaid expense		2,687		2,713
Other		1,544		1,296
Total	$	45,952	$	35,979

Accrued Liabilities

Accrued liabilities consist of the following (in thousands):

	December 31,
	2019		2018
Dividends and dividend equivalents	$	21,747	$	15,044
Stock rotation and sales returns		5,530		5,363
Customer prepayments		3,412		2,520
Income tax payable		2,435		7,018
Commissions		1,425		1,369
Operating lease liabilities		1,254		-
Warranty		1,139		4,564
Other		7,848		3,084
Total	$	44,790	$	38,962

Other Long-Term Liabilities

Other long-term liabilities consist of the following (in thousands):

	December 31,
	2019		2018
Deferred compensation plan liabilities	$	39,665	$	32,283
Dividend equivalents		6,265		6,145
Operating lease liabilities		1,103		-
Other		30		97
Total	$	47,063	$	38,525

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Note 1 - Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2019

Notes to Financial Statements

Significant Accounting Policies [Text Block]

1.  SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

Business

Monolithic Power Systems, Inc. (the “Company”) was incorporated in the State of California on August 22, 1997. On November 17, 2004, the Company was reincorporated in the State of Delaware. MPS designs, develops and markets integrated power semiconductor solutions and power delivery architectures. MPS’s mission is to provide innovative power solutions in the computing and storage, automotive, industrial, communications and consumer markets.

Basis of Presentation

The consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. Intercompany accounts and transactions have been eliminated in consolidation.

Use of Estimates

The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America (“GAAP”) requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements, and reported amounts of revenue and expenses during the reporting period. Significant estimates and assumptions used in these consolidated financial statements primarily include those related to revenue recognition, inventory valuation, valuation of share-based awards, contingencies and income tax valuation allowances. Actual results could differ from those estimates. 

Certain Significant Risks and Uncertainties

Financial instruments which potentially subject the Company to concentrations of credit risk consist primarily of cash and cash equivalents, short-term and long-term investments and accounts receivable. The Company’s cash consists of checking and savings accounts. The Company’s cash equivalents include short-term, highly liquid investments purchased with remaining maturities at the date of purchase of three months or less. The Company’s short-term investments may consist of corporate debt securities, certificates of deposit, commercial paper and government agency bonds and treasuries, and the long-term investments consist of government-backed student loan auction-rate securities. The Company generally does not require its customers to provide collateral or other security to support accounts receivable. To manage credit risk, management performs ongoing credit evaluations of its customers’ financial condition, monitors payment performance, and, in some cases, requires standby letters of credit. The Company also requires payment in advance for certain customers prior to shipments of goods. 

The Company participates in the dynamic high technology industry and believes that changes in any of the following areas could have a material adverse effect on its future financial position, results of operations or cash flows: advances and trends in new technologies and industry standards; competitive pressures in the form of new products or price reductions on current products; changes in product mix; changes in the overall demand for products offered by the Company; changes in third-party manufacturers; changes in key suppliers; changes in certain strategic relationships or customer relationships; litigation or claims against the Company based on intellectual property, patent, product, regulatory or other factors; fluctuations in foreign currency exchange rates; risk associated with changes in government policies and regulations on trade restrictions and corporate taxes; availability of necessary components or sub-assemblies; availability of foundry capacity; ability to integrate acquired companies; and the Company’s ability to attract and retain employees necessary to support its growth.

Foreign Currency  

In general, the functional currency of the Company’s international subsidiaries is the local currency. The primary subsidiaries are located in China, Taiwan and Europe, which utilize the Renminbi, the New Taiwan Dollar and the Euro as their currencies, respectively. Accordingly, assets and liabilities of the foreign subsidiaries are translated using exchange rates in effect at the end of the period. Revenue and costs are translated using average exchange rates for the period. The resulting translation adjustments are presented as a separate component of accumulated other comprehensive loss in stockholders’ equity on the Consolidated Balance Sheets. In addition, the Company incurs foreign currency exchange gain or loss related to certain intercompany transactions between the U.S. and its foreign subsidiaries that are denominated in a currency other than the functional currency. In connection with the settlement and remeasurement of the balances, the Company recorded foreign currency exchange gain (loss) of $(0.3) million, $1.0 million and $(0.6) million for the years ended December 31, 2019, 2018 and 2017, respectively, which were reported in interest and other income, net, on the Consolidated Statements of Operations.

Cash, Cash Equivalents and Investments 

The Company classifies all highly liquid investments with stated maturities of three months or less from date of purchase as cash equivalents. The Company may classify investments with maturities beyond one year as short-term based on the nature of the investments and their availability for use in current operations.

Cash equivalents are stated at cost, which approximates fair market value. The Company’s short-term and long-term debt investments are classified as available-for-sale securities and are stated at their fair market value, with unrealized gains and losses recorded in accumulated other comprehensive loss. Premiums and discounts on debt investments are generally amortized or accreted over the life of the related available-for-sale securities. Interest income is recognized when earned. The cost of investments sold is determined on a specific identification method.

The Company’s available-for-sale investments are subject to periodic impairment reviews. When a decline in the fair value of a debt security below its amortized cost is considered other-than-temporary, the Company records an impairment charge in interest and other income, net.

Fair Value of Financial Instruments

Fair value is defined as the price that would be received from selling an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. When determining the fair value, the Company considers the principal or most advantageous market in which the Company would transact, as well as assumptions that market participants would use when pricing the assets or liabilities. Fair value is estimated by applying the following hierarchy, which prioritizes the inputs used to measure fair value into three levels and bases the categorization within the hierarchy upon the lowest level of input that is available and significant to the fair value measurement:

● Level 1 - Observable inputs that reflect quoted prices (unadjusted) for identical assets or liabilities in active markets.

● Level 2 - Inputs that are based upon quoted prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are not active, and model-based valuation techniques for which all significant inputs are observable in the market or can be derived from observable market data.

● Level 3 - Significant unobservable inputs to the valuation methodology and typically reflect management’s estimates of assumptions that market participants would use in pricing the asset or liability.  

Inventories

Inventories are stated at the lower of standard cost (which approximates actual cost determined on a first-in first-out basis) and estimated net realizable value. The Company writes down excess and obsolete inventory based on its age and forecasted demand, which includes estimates taking into consideration the Company’s outlook on market and economic conditions, technology changes, new product introductions and changes in strategic direction. Actual demand may differ from forecasted demand, and such differences may have a material effect on recorded inventory values. When the Company records a write-down on inventory, it establishes a new, lower cost basis for that inventory, and subsequent changes in facts and circumstances will not result in the restoration or increase in that newly established cost basis.

Property and Equipment

Property and equipment are stated at cost. Depreciation commences when an asset is placed in service and available for its intended use. Depreciation is computed using the straight-line method over the estimated useful lives of the assets. Buildings and building improvements have estimated useful lives of 20 to 40 years. Leasehold improvements are amortized over the shorter of the estimated useful lives or the lease period. Production equipment and software have estimated useful lives of three to eight years. Transportation equipment has estimated useful lives of 5 to 20 years. Furniture and fixtures have estimated useful lives of three to five years. Land is not depreciated.

Impairment of Long-Lived Assets

The Company evaluates its long-lived assets other than goodwill for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. An impairment loss would be recognized when the sum of the undiscounted future net cash flows expected to result from the use of the asset and its eventual disposition is less than its carrying amount. Such impairment loss would be measured as the difference between the carrying amount of the asset and its fair value based on the present value of estimated future cash flows. The Company did not record material impairments in any of the periods presented.

Goodwill

Goodwill represents the excess of the fair value of purchase consideration over the fair value of net tangible and identified intangible assets as of the date of acquisition. Goodwill is not amortized.

The Company tests goodwill for impairment at least annually in the fourth quarter of the year, or whenever events or changes in circumstances indicate that goodwill may be impaired. The Company has elected to first assess the qualitative factors to determine whether it is more likely than not that the fair value of the reporting unit is less than its carrying amount. If the Company determines that it is more likely than not that its fair value is less than the carrying amount, then a quantitative goodwill impairment test is performed to measure the impairment loss. No impairment of goodwill has been identified in any of the periods presented.  

Deferred Compensation Plan 

The Company has a non-qualified, unfunded deferred compensation plan, which provides certain key employees, including executive officers, with the ability to defer the receipt of compensation in order to accumulate funds for retirement on a tax deferred basis. The Company does not make contributions to the plan or guarantee returns on the investments. The Company is responsible for the plan’s administrative expenses. Participants’ deferrals and investment gains and losses remain as the Company’s liabilities and the underlying assets are subject to claims of general creditors.

The liabilities for compensation deferred under the plan are recorded at fair value in each reporting period. Changes in the fair value of the liabilities are included in operating expense on the Consolidated Statements of Operations. The Company manages the risk of changes in the fair value of the liabilities by electing to match the liabilities with investments in corporate-owned life insurance policies, mutual funds and money market funds that offset a substantial portion of the exposure. The investments are recorded at the cash surrender value of the corporate-owned life insurance policies, and at the fair value of the mutual funds and money market funds, which are classified as trading securities. Changes in the cash surrender value of the corporate-owned life insurance policies and the fair value of mutual fund and money market fund investments are included in interest and other income, net on the Consolidated Statements of Operations. The following table summarizes the deferred compensation plan balances on the Consolidated Balance Sheets (in thousands):

	December 31,
	2019		2018
Deferred compensation plan asset components:
Cash surrender value of corporate-owned life insurance policies	$	16,883	$	13,103
Fair value of mutual funds and money market funds		21,975		18,867
Total	$	38,858	$	31,970
Deferred compensation plan assets reported in:
Other long-term assets	$	38,858	$	31,970
Deferred compensation plan liabilities reported in:
Accrued compensation and related benefits (short-term)	$	425	$	447
Other long-term liabilities		39,665		32,283
Total	$	40,090	$	32,730

Revenue Recognition

The Company recognizes revenue when it transfers control of promised goods or services to its customers in an amount that reflects the consideration to which it expects to be entitled to in exchange for those goods or services. See Note 2 for further discussion.

Research and Development

Costs incurred in research and development are expensed as incurred.

Warranty Reserve

The Company generally provides one to two-year warranties against defects in materials and workmanship and will either repair the products, provide replacements at no charge to customers or issue a refund. As they are considered assurance-type warranties, the Company does not account for them as separate performance obligations. Warranty reserve requirements are generally based on a specific assessment of the products sold with warranties when a customer asserts a claim for warranty or a product defect. See Note 13 for the changes in warranty reserves for the periods presented.

Leases

The Company determines if an arrangement is a lease at inception. Lease terms may include options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. Operating lease right-of-use (“ROU”) assets represent the Company’s right to use an underlying asset for the lease term and operating lease liabilities represent the Company’s obligation to make lease payments arising from the lease. Operating lease ROU assets and liabilities are recognized at the commencement date based on the present value of remaining lease payments over the lease term. ROU assets also include any initial direct costs incurred and prepaid lease payments, less lease incentives received. Because the implicit rate in each lease is not readily determinable, the Company uses its estimated incremental borrowing rate to determine the present value of the remaining lease payment. The Company recognizes operating lease costs on a straight-line basis over the lease term.

The Company does not record short-term leases with a term of 12 months or less at the commencement date on the Consolidated Balance Sheets. For lease arrangements that contain lease and non-lease components, the Company accounts for them as single lease components.

For lease arrangements where the Company is the lessor, the Company recognizes lease income from operating leases on a straight-line basis over the lease term.

Stock-Based Compensation

The Company measures the cost of employee services received in exchange for an award of equity instruments based on the grant-date fair value of the award. The fair value of RSUs with service conditions or performance conditions is based on the grant date stock price. The fair value of shares issued under the ESPP and RSUs with a purchase price feature is estimated using the Black-Scholes model. The fair value of RSUs with market conditions, as well as RSUs containing both market and performance conditions, is estimated using a Monte Carlo simulation model. 

Compensation expense related to awards with service conditions is recorded on a straight-line basis over the requisite service period. Compensation expense related to awards subject to market or performance conditions is recognized over the requisite service period for each separately vesting tranche. For awards with only market conditions, compensation expense is not reversed if the market conditions are not satisfied. For awards with performance conditions, as well as awards containing both market and performance conditions, the Company recognizes compensation expense when the performance goals are achieved, or when it becomes probable that the performance goals will be achieved. Management performs the probability assessment on a quarterly basis by reviewing external factors, such as macroeconomic conditions and the analog industry revenue forecasts, and internal factors, such as the Company’s business and operational objectives and revenue forecasts. Changes in the probability assessment of achievement of the performance conditions are accounted for in the period of change by recording a cumulative catch-up adjustment as if the new estimate had been applied since the service inception date. Any previously recognized compensation expense is reversed if the performance conditions are not expected to be satisfied as a result of management’s assessment.

The Company accounts for forfeitures of equity awards when they occur.

Accounting for Income Taxes 

The Company recognizes federal, state and foreign current tax liabilities or assets based on its estimate of taxes payable or refundable in the current fiscal year by tax jurisdiction. The Company also recognizes federal, state and foreign deferred tax assets or liabilities for its estimate of future tax effects attributable to temporary differences and carryforwards. The Company records a valuation allowance to reduce any deferred tax assets by the amount of any tax benefits that, based on available evidence and judgment, are not expected to be realized.

The Company’s calculation of current and deferred tax assets and liabilities is based on certain estimates and judgments and involves dealing with uncertainties in the application of complex tax laws. The Company’s estimates of current and deferred tax assets and liabilities may change based, in part, on added certainty, finality or uncertainty to an anticipated outcome, changes in accounting or tax laws in the U.S. or foreign jurisdictions where the Company operates, or changes in other facts or circumstances. In addition, the Company recognizes liabilities for potential U.S. and foreign income tax for uncertain income tax positions taken on its tax returns if it has less than a 50% likelihood of being sustained. If the Company determines that payment of these amounts is unnecessary or if the recorded tax liability is less than its current assessment, the Company may be required to recognize an income tax benefit or additional income tax expense in its financial statements in the period such determination is made. The Company has calculated its uncertain tax positions which were attributable to certain estimates and judgments.

Litigation and Contingencies

The Company is a party to actions and proceedings in the ordinary course of business, including potential litigation regarding its stockholders and its intellectual property, challenges to the enforceability or validity of its intellectual property, claims that the Company’s products infringe on the intellectual property rights of others, and employment matters. The pending proceedings involve complex questions of fact and law and will require the expenditure of significant funds and the diversion of other resources to prosecute and defend. In addition, from time to time, the Company becomes aware that it is subject to other contingent liabilities. When this occurs, the Company will evaluate the appropriate accounting for the potential contingent liabilities to determine whether a contingent liability should be recorded. In making this determination, management may, depending on the nature of the matter, consult with internal and external legal counsel and technical experts. Based on the facts and circumstances in each matter, the Company uses its judgment to determine whether it is probable that a contingent loss has occurred and whether the amount of such loss can be estimated. If the Company determines a loss is probable and estimable, the Company records a contingent loss. In determining the amount of a contingent loss, the Company takes into account advice received from experts for each specific matter regarding the status of legal proceedings, settlement negotiations, prior case history and other factors. Should the judgments and estimates made by management need to be adjusted as additional information becomes available, the Company may need to record additional contingent losses. Alternatively, if the judgments and estimates made by management are adjusted, for example, if a particular contingent loss does not occur, the contingent loss recorded would be reversed.

Litigation expense recorded on the Consolidated Statements of Operations includes primarily patent infringement litigation and other business matters. The Company records litigation costs in the period in which they are incurred. Proceeds resulting from settlement of litigation or favorable judgments are recorded as a reduction against litigation expense.

Net Income per Share

Basic net income per share is computed by dividing net income by the weighted-average number of common shares outstanding for the period. Diluted net income per share reflects the potential dilution that would occur if outstanding securities or other contracts to issue common stock were exercised or converted into common shares, and calculated using the treasury stock method. Contingently issuable shares, including equity awards with performance conditions or market conditions, are considered outstanding common shares and included in the basic net income per share as of the date that all necessary conditions to earn the awards have been satisfied. Prior to the end of the contingency period, the number of contingently issuable shares included in the diluted net income per share is based on the number of shares, if any, that would be issuable under the terms of the arrangement at the end of the reporting period.

The Company’s RSUs contain forfeitable rights to receive cash dividend equivalents, which are accumulated and paid to the employees when the underlying RSUs vest. Dividend equivalents accumulated on the underlying RSUs are forfeited if the employees do not fulfill the requisite service requirement and, as a result, the awards do not vest. Accordingly, these awards are not treated as participating securities in the net income per share calculation. 

Comprehensive Income 

Comprehensive income represents the change in the Company’s net assets during the period from non-owner sources. Accumulated other comprehensive loss presented on the Consolidated Balance Sheets primarily consists of unrealized gains or losses related to available-for-sale investments and foreign currency translation adjustments.

Recently Adopted Accounting Pronouncement

In  February 2016, the FASB issued Accounting Standards Update (“ASU”) No. 2016-02, Leases (Topic 842), which requires entities to recognize ROU assets and lease liabilities on the balance sheets for leases with terms greater than 12 months. In addition, the standard applies to leases embedded in service or other arrangements. The Company adopted the standard on  January 1, 2019 using the modified retrospective transition method and did not restate comparative periods, as permitted by the standard. In addition, the Company elected the transition practical expedients to not reassess whether its outstanding contracts as of December 31, 2018 contained or were leases, classification of its existing leases and lease terms.

Upon adoption, the Company recognized ROU assets and lease liabilities of its outstanding operating leases on the Consolidated Balance Sheets, primarily related to real estate. The adoption did not have a material impact on the Consolidated Statements of Operations or the Consolidated Statements of Cash Flows. See Note 7 for further discussion.

Recent Accounting Pronouncements Not Yet Adopted as of December 31, 2019

In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes, which eliminates certain exceptions related to the approach for intra-period tax allocation, the methodology for calculating income taxes in an interim period and the recognition of deferred tax liabilities for outside basis differences. The standard also clarifies and simplifies other aspects of the accounting for income taxes. The standard will be effective for annual reporting periods beginning after December 15, 2020. Early adoption is permitted. The standard will generally be applied prospectively, with certain exceptions. The Company is evaluating the impact of the adoption on its consolidated financial statements.

In  August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework — Changes to the Disclosure Requirements for Fair Value Measurement, which changes certain disclosure requirements, including those related to Level 3 fair value measurements. The standard will be effective for annual reporting periods beginning after  December 15, 2019. The Company does not expect the adoption of this standard to have a material impact on its disclosures.

In  January 2017, the FASB issued ASU No. 2017-04, Intangibles – Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment, which simplifies the accounting for goodwill impairment. The guidance removes step two of the goodwill impairment test, which requires a hypothetical purchase price allocation to measure the amount of a goodwill impairment. A goodwill impairment will now be the amount by which a reporting unit’s carrying value exceeds its fair value, not to exceed the carrying amount of goodwill. Entities will continue to have the option to perform a qualitative assessment to determine if a quantitative impairment test is necessary. The standard will be applied prospectively, and will be effective for annual reporting periods beginning after  December 15, 2019. The Company will continue to perform the qualitative assessment on its goodwill impairment test and does not expect the adoption of this standard to have a material impact.

In  June 2016, the FASB issued ASU No. 2016-13, Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, which introduces a model based on expected losses to estimate credit losses for financial assets held at amortized cost. In addition, for available-for-sale debt securities, the standard eliminates the concept of other-than-temporary impairment and entities will be required to recognize an allowance for credit losses rather than reductions in the amortized cost of the securities. The standard will be effective for annual reporting periods beginning after  December 15, 2019. Entities will apply the standard by recording a cumulative-effect adjustment to retained earnings. The effect of the standard on the Company’s available-for-sale debt securities will largely depend on the composition of the investment portfolio, the financial condition of the issuers, the credit quality and expected collectability of the securities, and economic conditions. The Company does not expect the standard to have a material impact on its consolidated financial statements at the time of adoption.

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Note 14 - Employee 401(k) Plan (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Contribution Plan, Employer Discretionary Contribution Amount	$ 0	$ 0	$ 0

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Note 10 - Interest and Other Income, Net - Interest and Other Income Components (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Interest income									$ 7,305	$ 6,321	$ 5,353
Amortization of premium on available-for-sale securities									(729)	(1,353)	(1,976)
Gain (loss) on deferred compensation plan investments									3,806	(1,022)	2,531
Foreign currency exchange gain (loss)									(310)	953	(550)
Other									486	95	162
Total	$ 2,731	$ 2,257	$ 2,229	$ 3,341	$ (393)	$ 2,714	$ 2,232	$ 440	$ 10,558	$ 4,994	$ 5,520

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Note 12 - Income Taxes (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Transition Tax Liability	$ 24,600
Payment for the Transition Tax	1,300	$ 2,600
GILTI Income	58,600	81,100
Undistributed Earnings of Foreign Subsidiaries	$ 32,900
Percent of Dividend Received Deduction	100.00%
Unrecognized Tax Benefits, Ending Balance	$ 25,407	20,491	$ 16,272	$ 14,431
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	17,300	12,800
Unrecognized Tax Benefits, Interest on Income Taxes Accrued	1,600	900
Domestic Tax Authority [Member]
Operating Loss Carryforwards, Total	0
Domestic Tax Authority [Member] | Research Tax Credit Carryforward [Member]
Tax Credit Carryforward, Amount	0
State and Local Jurisdiction [Member] | Internal Revenue Service (IRS) [Member]
Operating Loss Carryforwards, Total	12,600
State and Local Jurisdiction [Member] | Internal Revenue Service (IRS) [Member] | Research Tax Credit Carryforward [Member]
Operating Loss Carryforwards, Total	24,100
Bermuda Subsidiary [Member]
Foreign Earnings Repatriated	75,000
Accrued Liabilities, Current [Member]
Transition Tax Liability	2,000	1,300
Income Tax Liabilities, Noncurrent [Member]
Transition Tax Liability	$ 18,700	$ 20,700

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Note 7 - Leases - Maturities of Income Related to Lease Payments (Details) $ in Thousands	Dec. 31, 2019 USD ($)
2020	$ 1,523
2021	1,378
2022	1,138
2023	604
2024	552
Thereafter	45
Total	$ 5,240

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Note 8 - Stock-based Compensation - Valuation Assumptions (Details) - 2004 Employee Stock Plan [Member] - Employee Stock Purchase Plan [Member]	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Expected term (Year)	6 months	6 months	6 months
Expected volatility	37.00%	29.50%	23.50%
Risk-free interest rate	2.20%	2.00%	0.90%
Dividend yield	1.10%	1.00%	0.90%

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Note 12 - Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Tax credits	$ 18,080	$ 11,833
Stock-based compensation	6,237	10,040
Deferred compensation	7,110	6,829
Net operating losses	615	1,133
Other expenses not currently deductible	2,323	1,852
Deferred tax assets, gross	34,365	31,687
Valuation allowance	(15,411)	(13,041)
Deferred tax assets, net of valuation allowance	18,954	18,646
Depreciation and amortization	(1,259)	(711)
Undistributed foreign earnings	(77)	(1,105)
Other expenses currently deductible	(425)	0
Deferred tax liabilities	(1,761)	(1,816)
Net deferred tax assets	$ 17,193	$ 16,830

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Note 5 - Balance Sheet Components (Details Textual) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Depreciation, Total	$ 14.5	$ 11.4	$ 14.0

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Note 3 - Cash, Cash Equivalents, Investments and Restricted Cash - Restricted Cash (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash and cash equivalents	$ 172,960	$ 172,704
Restricted cash included in other long-term assets	116	114
Total cash, cash equivalents and restricted cash reported on the Consolidated Statements of Cash Flows	$ 173,076	$ 172,818	$ 82,874	$ 112,813

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Note 4 - Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2019

Notes Tables

Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block]

	December 31, 2019
	Total		Level 1		Level 2		Level 3
Money market funds	$	28,100	$	28,100	$	-	$	-
Corporate debt securities		260,950		-		260,950		-
Commercial paper		1,994		-		1,994		-
U.S. treasuries and government agency bonds		19,493		-		19,493		-
Auction-rate securities backed by student-loan notes		3,138		-		-		3,138
Mutual funds and money market funds under deferred compensation plan		21,975		21,975		-		-
Total	$	335,650	$	50,075	$	282,437	$	3,138

	December 31, 2018
	Total		Level 1		Level 2		Level 3
Money market funds	$	41,135	$	41,135	$	-	$	-
Corporate debt securities		170,909		-		170,909		-
U.S. treasuries and government agency bonds		32,068		-		32,068		-
Certificates of deposit		1,600		-		1,600		-
Auction-rate securities backed by student-loan notes		3,241		-		-		3,241
Mutual funds and money market funds under deferred compensation plan		18,867		18,867		-		-
Total	$	267,820	$	60,002	$	204,577	$	3,241

Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block]

Balance at January 1, 2018	$	5,256
Change in unrealized loss included in other comprehensive income		(15	)
Sale and settlement at par		(2,000	)
Balance at December 31, 2018		3,241
Change in unrealized gain included in other comprehensive income		147
Sale and settlement at par		(250	)
Balance at December 31, 2019	$	3,138

Schedule Of Level 3 Assumptions [Table Text Block]

	December 31,
	2019			2018
Time-to-liquidity (in years)	2	-	3	2	-	3
Discount rate	4.0%	-	8.3%	4.9%	-	10.1%

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Note 8 - Stock-based Compensation (Tables)

12 Months Ended

Dec. 31, 2019

Notes Tables

Share-based Payment Arrangement, Cost by Plan [Table Text Block]

	Year Ended December 31,
	2019		2018		2017
Cost of revenue	$	2,409	$	1,888	$	1,654
Research and development		19,584		15,990		14,816
Selling, general and administrative		56,706		42,729		36,147
Total stock-based compensation expense	$	78,699	$	60,607	$	52,617
Tax benefit related to stock-based compensation	$	2,754	$	4,383	$	5,054

Share-based Payment Arrangement, Restricted Stock and Restricted Stock Unit, Activity [Table Text Block]

	Time-Based RSUs					PSUs and MPSUs					MSUs					Total
	Number of Shares			Weighted-Average Grant Date Fair Value Per Share		Number of Shares			Weighted-Average Grant Date Fair Value Per Share		Number of Shares			Weighted-Average Grant Date Fair Value Per Share		Number of Shares			Weighted-Average Grant Date Fair Value Per Share
Outstanding at January 1, 2017		366		$	51.35		2,284		$	43.24		1,620		$	23.57		4,270		$	36.47
Granted		81		$	94.25		585	(1)	$	62.72		-		$	-		666		$	66.56
Vested		(175	)	$	48.35		(597	)	$	41.94		-		$	-		(772	)	$	43.39
Forfeited		(14	)	$	61.80		(6	)	$	49.82		-		$	-		(20	)	$	58.46
Outstanding at December 31, 2017		258		$	66.30		2,266		$	48.59		1,620		$	23.57		4,144		$	39.91
Granted		133		$	114.36		630	(1)	$	85.06		600		$	68.48		1,363		$	80.62
Vested		(136	)	$	60.23		(717	)	$	41.08		-		$	-		(853	)	$	44.13
Forfeited		(15	)	$	82.20		(5	)	$	63.16		(1	)	$	68.48		(21	)	$	76.92
Outstanding at December 31, 2018		240		$	95.38		2,174		$	61.61		2,219		$	35.69		4,633		$	50.94
Granted		52		$	141.32		512	(1)	$	99.88		-		$	-		564		$	103.68
Vested		(103	)	$	81.53		(656	)	$	53.72		(324	)	$	23.57		(1,083	)	$	47.34
Forfeited		(9	)	$	117.31		(43	)	$	42.72		(9	)	$	68.48		(61	)	$	57.01
Outstanding at December 31, 2019		180		$	115.45		1,987		$	74.50		1,886		$	37.63		4,053		$	59.16

Schedule of Share-based Payment Award, Employee Stock Purchase Plan, Valuation Assumptions [Table Text Block]

	Year Ended December 31,
	2019			2018			2017
Expected term (in years)		0.5			0.5			0.5
Expected volatility		37.0	%		29.5	%		23.5	%
Risk-free interest rate		2.2	%		2.0	%		0.9	%
Dividend yield		1.1	%		1.0	%		0.9	%

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Note 6 - Real Estate Transaction

12 Months Ended

Dec. 31, 2019

Notes to Financial Statements

Real Estate Transaction [Text Block]

6. REAL ESTATE TRANSACTION

In  March 2019, the Company completed the purchase of an office building and land located in Kirkland, Washington for $52.9 million in cash. The property also had in-place leases for a portion of the building which were assumed by the Company. The Company accounted for the purchase as an asset acquisition and capitalized $0.4 million of transaction costs.

The purchase price allocation was as follows (in thousands):

Building	$	30,078
Land		22,254
In-place leases		981
Total	$	53,313

The fair value of the building was determined based on the income approach, which considered the discounted cash flows and direct capitalization analysis, and the sales comparison approach. The fair value of land was determined based on the sales comparison approach. The fair value of the in-place leases was determined primarily based on the analysis of the economic benefits of certain cost savings attributable to the leases.

The building is depreciated over a useful life of 40 years and the in-place leases are amortized over the average remaining lease terms of 3.5 years.

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Note 2 - Revenue Recognition

12 Months Ended

Dec. 31, 2019

Notes to Financial Statements

Revenue from Contract with Customer [Text Block]

2. REVENUE RECOGNITION

The Company adopted ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606), on  January 1, 2018 using the modified retrospective transition method applied to those contracts which were not completed as of  December 31, 2017. Results for reporting periods beginning after  January 1, 2018 are presented under Topic 606, while prior-period amounts have not been retrospectively adjusted and were reported in accordance with Topic 605, Revenue Recognition.

Revenue from Product Sales

The Company generates revenue primarily from product sales, which include assembled and tested integrated circuits, as well as dies in wafer form. These product sales were 99%, 98% and 98% of the Company’s total revenue for the years ended December 31, 2019, 2018 and 2017, respectively. The remaining revenue primarily includes royalty revenue from licensing arrangements and revenue from wafer testing services performed for third parties, which have not been significant in all periods presented. See Note 16 for the disaggregation of the Company’s revenue by geographic regions and by product families.

The Company sells its products primarily through third-party distributors, value-added resellers, OEMs, ODMs and EMS providers. For the years ended December 31, 2019, 2018 and 2017, 83%, 87% and 88%, respectively, of the Company’s product sales were made through distribution arrangements. These distribution arrangements contain enforceable rights and obligations specific to those distributors and not the end customers. Purchase orders, which are generally governed by sales agreements or the Company's standard terms of sale, set the final terms for unit price, quantity, shipping and payment agreed by both parties. The Company considers purchase orders to be the contracts with customers. The unit price as stated on the purchase orders is considered the observable, stand-alone selling price for the arrangements.

The Company recognizes revenue when it satisfies a performance obligation by transferring control of the promised goods or services to its customers, in an amount that reflects the consideration the Company expects to be entitled to in exchange for those goods or services. The Company excludes taxes assessed by government authorities, such as sales taxes, from revenue.

Product sales consist of a single performance obligation that the Company satisfies at a point in time. The Company recognizes product revenue from distributors and direct end customers when the following events have occurred: (a) the Company has transferred physical possession of the products, (b) the Company has a present right to payment, (c) the customer has legal title to the products, and (d) the customer bears significant risks and rewards of ownership of the products. In accordance with the shipping terms specified in the contracts, these criteria are generally met when the products are shipped from the Company’s facilities (such as the “Ex Works” shipping term) or delivered to the customers’ locations (such as the “Delivered Duty Paid” shipping term).

Under certain consignment agreements, revenue is not recognized when the products are shipped and delivered to be held at customers’ designated locations because the Company continues to control the products and retain ownership, and the customers do not have an unconditional obligation to pay. The Company recognizes revenue when the customers consume the products from the consigned inventory locations or, in some cases, after a 60-day period from the delivery date has passed, at which time control transfers to the customers and the Company invoices them for payment.

Variable Consideration

The Company accounts for price adjustment and stock rotation rights as variable consideration that reduces the transaction price, and recognizes that reduction in the same period the associated revenue is recognized. Three U.S.-based distributors have price adjustment rights when they sell the Company’s products to their end customers at a price that is lower than the distribution price invoiced by the Company. When the Company receives claims from the distributors that products have been sold to the end customers at the lower price, the Company issues the distributors credit memos for the price adjustments. The Company estimates the price adjustments using the expected value method based on an analysis of historical claims, at both the distributor and product level, as well as an assessment of any known trends of product sales mix. Other U.S. distributors and non-U.S. distributors, which make up the majority of the Company’s total sales to distributors, do not have price adjustment rights. The Company records a credit against accounts receivable for the estimated price adjustments, with a corresponding reduction to revenue.

Certain distributors have limited stock rotation rights that permit the return of a small percentage of the previous six months’ purchases in accordance with the contract terms. The Company estimates the stock rotation returns using the expected value method based on an analysis of historical returns, and the current level of inventory in the distribution channel. The Company records a liability for the stock rotation reserve, with a corresponding reduction to revenue. In addition, the Company recognizes an asset for product returns which represents the right to recover products from the customers related to stock rotations, with a corresponding reduction to cost of revenue.

Contract Balances

The Company records a receivable when it has an unconditional right to receive consideration after the performance obligations are satisfied. As of  December 31, 2019 and 2018, accounts receivable totaled $52.7 million and $55.2 million, respectively. The Company did not record any allowance for doubtful accounts as of  December 31, 2019 and 2018.

For certain customers located in Asia, the Company requires cash payments two weeks before the products are scheduled to be shipped to the customers. The Company records these payments received in advance of performance as customer prepayments within current accrued liabilities. As of  December 31, 2019 and 2018, customer prepayments totaled $3.4 million and $2.5 million, respectively. The increase in the customer prepayment balance for the year ended  December 31, 2019 resulted from an increase in unfulfilled customer orders for which the Company has received payments. For the year ended December 31, 2019, the Company recognized $2.5 million of revenue that was included in the customer prepayment balance as of  December 31, 2018.

Practical Expedients

The Company has elected the practical expedient to expense sales commissions as incurred because the amortization period would have been one year or less. 

The Company’s standard payment terms generally require customers to pay 30 to 60 days after the Company satisfies the performance obligations. For those customers who are required to pay in advance, the Company satisfies the performance obligations generally within two weeks. The Company has elected not to determine whether contacts with customers contain significant financing components.

The Company’s unsatisfied performance obligations primarily include products held in consignment arrangements and customer purchase orders for products that the Company has not yet shipped. Because the Company expects to fulfill these performance obligations within one year, the Company has elected not to disclose the amount of these remaining performance obligations or the timing of recognition.

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Note 10 - Interest and Other Income, Net

12 Months Ended

Dec. 31, 2019

Notes to Financial Statements

Other Nonoperating Income and Expense [Text Block]

10. INTEREST AND OTHER INCOME, NET

The components of interest and other income, net, are as follows (in thousands):

	Year Ended December 31,
	2019			2018			2017
Interest income	$	7,305		$	6,321		$	5,353
Amortization of premium on available-for-sale securities		(729	)		(1,353	)		(1,976	)
Gain (loss) on deferred compensation plan investments		3,806			(1,022	)		2,531
Foreign currency exchange gain (loss)		(310	)		953			(550	)
Other		486			95			162
Total	$	10,558		$	4,994		$	5,520

For the year ended December 31, 2019, “other” includes a $0.7 million gain recognized from the sale of a parcel of land, net of certain capitalized costs and selling expenses.

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Note 18 - Subsequent Event

12 Months Ended

Dec. 31, 2019

Notes to Financial Statements

Subsequent Events [Text Block]

18. SUBSEQUENT EVENT

Cash Dividend Increase

In February 2020, the Company’s Board of Directors approved an increase in quarterly cash dividends from $0.40 per share to $0.50 per share.

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Note 14 - Employee 401(k) Plan

12 Months Ended

Dec. 31, 2019

Notes to Financial Statements

Pension and Other Postretirement Benefits Disclosure [Text Block]

14.  EMPLOYEE 401(k) PLAN

The Company sponsors a 401(k) retirement savings plan for all employees in the U.S. who meet certain eligibility requirements. Participants may contribute up to the amount allowable as a deduction for federal income tax purposes. The Company is not required to contribute and did not contribute to the plan for the years ended December 31, 2019, 2018 and 2017.

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Consolidated Statements of Comprehensive Income (Parentheticals) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Change in unrealized gain (loss) on available-for-sale securities, tax	$ (203)	$ 209	$ 0

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Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 172,960	$ 172,704
Short-term investments	282,437	204,577
Accounts receivable, net	52,704	55,214
Inventories	127,500	136,384
Other current assets	19,605	11,931
Total current assets	655,206	580,810
Property and equipment, net	228,315	150,001
Long-term investments	3,138	3,241
Goodwill	6,571	6,571
Deferred tax assets, net	17,193	16,830
Other long-term assets	45,952	35,979
Total assets	956,375	793,432
Current liabilities:
Accounts payable	27,271	22,678
Accrued compensation and related benefits	26,164	18,799
Other accrued liabilities	44,790	38,962
Total current liabilities	98,225	80,439
Income tax liabilities	37,596	34,375
Other long-term liabilities	47,063	38,525
Total liabilities	182,884	153,339
Commitments and contingencies
Stockholders’ equity:
Common stock and additional paid-in capital: $0.001 par value; shares authorized: 150,000; shares issued and outstanding: 43,616 and 42,505, respectively	549,517	450,908
Retained earnings	229,450	194,728
Accumulated other comprehensive loss	(5,476)	(5,543)
Total stockholders’ equity	773,491	640,093
Total liabilities and stockholders’ equity	$ 956,375	$ 793,432

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Note 18 - Subsequent Event (Details Textual) - $ / shares	1 Months Ended	3 Months Ended	12 Months Ended
	Feb. 28, 2020	Dec. 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Common Stock, Dividends, Per Share, Declared		$ 0.40	$ 1.60	$ 1.20	$ 0.80
Subsequent Event [Member]
Common Stock, Dividends, Per Share, Declared	$ 0.50

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Note 6 - Real Estate Transaction - Allocation of Consideration (Details) - Property in Kirkland, Washington [Member] $ in Thousands	Mar. 31, 2019 USD ($)
Building	$ 30,078
Land	22,254
In-place leases	981
Total	$ 53,313

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Note 5 - Balance Sheet Components - Other Long-term Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred compensation plan assets	$ 38,858	$ 31,970
Operating lease ROU assets	2,863	0
Prepaid expense	2,687	2,713
Other	1,544	1,296
Total	$ 45,952	$ 35,979

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Note 16 - Segment and Geographic Information - Revenue by Region (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenue	$ 166,738	$ 168,813	$ 151,007	$ 141,363	$ 153,497	$ 159,975	$ 139,761	$ 129,150	$ 627,921	$ 582,382	$ 470,929
CHINA
Revenue									382,740	334,726	257,787
TAIWAN, PROVINCE OF CHINA
Revenue									73,801	75,307	83,357
Europe [Member]
Revenue									49,467	49,484	38,140
KOREA, REPUBLIC OF
Revenue									43,900	41,238	34,155
South East Asia [Member]
Revenue									32,031	36,495	25,755
JAPAN
Revenue									27,812	26,853	20,187
UNITED STATES
Revenue									17,836	17,621	11,113
Other Region [Member]
Revenue									$ 334	$ 658	$ 435

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Note 7 - Leases - Future Minimum Payments Under Non-cancelable Operating Leases (Details) $ in Thousands	Dec. 31, 2019 USD ($)
2019	$ 1,511
2020	872
2021	273
2022	195
2023	26
Total	$ 2,877

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Note 15 - Significant Customers (Tables)

12 Months Ended

Dec. 31, 2019

Notes Tables

Schedule of Revenue by Major Customers by Reporting Segments [Table Text Block]

	Revenue									Accounts Receivable
	Year Ended December 31,									December 31,
Customer	2019			2018			2017			2019			2018
Company A (distributor)		23	%		22	%		17	%		24	%		25	%
Company B (distributor)		*			10	%		*			11	%		16	%
Company C (distributor)		*			*			10	%		*			*
Company A (value-added reseller)		*			*			*			13	%		*

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Note 1 - Summary of Significant Accounting Policies (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Foreign Currency Transaction Gain (Loss), before Tax, Total	$ (310)	$ 953	$ (550)
Goodwill, Impairment Loss	$ 0	0	0
Minimum [Member]
Warranty Term	1 year
Maximum [Member]
Warranty Term	2 years
Building and Building Improvements [Member] | Minimum [Member]
Property, Plant and Equipment, Useful Life	20 years
Building and Building Improvements [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life	40 years
Computer Equipment [Member] | Minimum [Member]
Property, Plant and Equipment, Useful Life	3 years
Computer Equipment [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life	8 years
Transportation Equipment [Member] | Minimum [Member]
Property, Plant and Equipment, Useful Life	5 years
Transportation Equipment [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life	20 years
Furniture and Fixtures [Member] | Minimum [Member]
Property, Plant and Equipment, Useful Life	3 years
Furniture and Fixtures [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life	5 years
Interest and Other Income [Member]
Foreign Currency Transaction Gain (Loss), before Tax, Total	$ (300)	$ 1,000	$ (600)