Reclassification, Policy [Policy Text Block]

Revisions

In connection with the preparation of the Company’s 2019 year-end consolidated financial statements, a classification error in the Company’s previously issued consolidated statements of cash flows was identified. Specifically, it was determined that payments made under the Company’s multi-year agreements for the purchase of internal use intangible assets should have been classified as use of cash for financing activities and not as use of cash for investing activities as originally presented. Such classification error had no impact on the Company’s consolidated balance sheets, statements of income (loss), statements of comprehensive income (loss) or statements of stockholders’ equity. The Company has concluded that such classification error did not result in the previously issued financial statements being materially misstated. However, the Company has revised the accompanying 2018 and 2017 consolidated statements of cash flows to correct for such classification error. The effect of the revisions on the consolidated statement of cash flows for the year ended December 31, 2018 was as follows: (i) cash used in investing activities decreased $21,311 from $56,961 to $35,650, and (ii) cash used in financing activities increased $21,311 from $12,630 to $33,941. The effect of the revisions on the consolidated statement of cash flows for the year ended December 31, 2017 was as follows: (i) cash used in investing activities decreased $13,688 from $38,341 to $24,653, and (ii) cash used in financing activities increased $13,688 from $20,384 to $34,072.

See also note 18 for further information regarding the impact of this classification error on the Company’s 2019 and 2018 unaudited interim condensed consolidated financial statements.

Foreign Currency Transactions and Translations Policy [Policy Text Block]

Foreign Currency Translation

The Company and its subsidiaries use the U.S. dollar as its functional currency. Foreign currency assets and liabilities are remeasured into U.S. dollars at the end-of-period exchange rates except for non-monetary assets and liabilities, which are remeasured at historical exchange rates. Revenue and expenses are remeasured at the exchange rate in effect during the period the transaction occurred, except for those expenses related to balance sheet amounts, which are remeasured at historical exchange rates. Gains or losses from foreign currency transactions are included in the consolidated statements of income (loss) as part of “other income, net.” Foreign currency gain (loss) in 2019, 2018 and 2017 were ($453), ($135) and $22, respectively.

Fair Value of Financial Instruments, Policy [Policy Text Block]

Fair Market Value of Financial Instruments

The carrying amount reflected in the balance sheet for cash and cash equivalents, accounts receivable, prepaid and other current assets, accounts payable and other current liabilities, approximate fair value due to the short-term nature of these financial instruments.

Inventory, Policy [Policy Text Block]

Inventories

Inventories are stated at the lower of cost and net realizable value. Cost is computed using standard cost, which approximates actual cost, on a first-in, first-out basis. Inventories are reduced for write-downs based on periodic reviews for evidence of slow-moving or obsolete parts. The write-down is based on the comparison between inventory on hand and forecasted customer demand for each specific product. Once written down, inventory write-downs are not reversed until the inventory is sold or scrapped. Inventory write-downs are also established when conditions indicate the net realizable value is less than cost due to physical deterioration, technological obsolescence, changes in price level or other causes.

Intangible Assets, Finite-Lived, Policy [Policy Text Block]

Intangible Assets

Intangible assets represent rights acquired for developed technology, customer relationships, trademarks, patents and in-process research and development (“IPR&D”) in connection with business acquisitions. Intangible assets with finite useful lives are amortized over periods ranging from one to ten years using a method that reflects the pattern in which the economic benefits of the intangible asset are consumed, or if that pattern cannot be reliably determined, using a straight-line amortization method. Acquired IPR&D is capitalized and amortization commences upon completion of the underlying projects. If any of the projects are abandoned, the Company would be required to impair the related IPR&D asset.

Goodwill and Intangible Assets, Goodwill, Policy [Policy Text Block]

Goodwill

Goodwill is recorded when consideration paid for a business acquisition exceeds the fair value of net tangible and intangible assets acquired. Goodwill is measured and tested for impairment on an annual basis during the fourth fiscal quarter or more frequently if the Company believes indicators of impairment exist.

To review for impairment, the Company first assesses qualitative factors to determine whether events or circumstances lead to a determination that it is more likely than not that the fair value of its reporting unit is less than its carrying amount. The qualitative assessment of the recoverability of goodwill, whether performed annually or based on specific events or circumstances, considers various macroeconomic, industry-specific and company-specific factors. Those factors include: (i) severe adverse industry or economic trends; (ii) significant company-specific actions, including exiting an activity in conjunction with restructuring of operations; (iii) current, historical or projected deterioration of its financial performance; or (iv) a sustained decrease in its market capitalization below its net book value. After assessing the totality of events and circumstances, if the Company determines that it is not more likely than not that the fair value of its reporting unit is less than its carrying amount, no further assessment is performed. If however, the Company determines that it is more likely than not that the fair value of the reporting unit is less than its carrying amount, an impairment loss is recognized in an amount equal to the excess. There was no impairment of goodwill in 2019, 2018 and 2017.

Revenue [Policy Text Block]

Revenue Recognition

Prior to January 1, 2018, the Company recognized revenue when there was persuasive evidence of an arrangement, delivery had occurred, the fee was fixed or determinable, and collection was reasonably assured.

On January 1, 2018, the Company adopted Accounting Standards Update (ASU) 2014-09, Revenue from Contracts with Customers (Topic 606), using the modified retrospective method applied to those contracts which were not completed as of January 1, 2018. The adoption of this guidance resulted in no cumulative effect adjustment as of January 1, 2018. Starting January 1, 2018, the Company recognizes revenue on sales to distributors upon shipment and transfer of control (known as “sell-in” revenue recognition), rather than deferring recognition until distributors report that they have sold the products to their customers (known as “sell-through” revenue recognition). The impact of the adoption on revenue and cost of revenue for the year ended December 31, 2018 was an increase of $3,778 and $779, respectively. Deferred revenue and inventories decreased by $3,778 and $779 as of December 31, 2018, respectively. Results for reporting periods beginning after January 1, 2018 are presented under the new revenue guidance, while prior periods were not retrospectively adjusted and continue to be reported in accordance with the Company’s historic revenue recognition accounting.

The following table shows revenue by geography, based on the receiving location of customers:

	*Year Ended December 31,*
	*2019*		*2018*		*2017*
	(in thousands)
China	$	164,715	$	113,684	$	114,168
United States		103,402		87,545		92,620
Thailand		54,468		40,884		45,205
Other		43,050		52,377		96,208
	$	365,635	$	294,490	$	348,201

The Company recognizes revenue when control of the promised goods or services is transferred to customers in an amount that reflects the consideration the Company expects to receive in exchange for such goods or services.

Product Revenue

The Company’s products are fully functional at the time of shipment and do not require additional production, modification, or customization. The Company recognizes revenue upon transfer of control at a point in time when title transfers either upon shipment to or receipt by the customer, net of accruals for estimated sales returns and allowances. Sales and other taxes the Company collects are excluded from revenue. The fee is based on specific products and quantities to be delivered at specified prices, which is evidenced by a customer purchase order or other evidence of an arrangement. Certain distributors may receive a credit for price discounts associated with the distributors' customers that purchased those products. The Company estimates the extent of these distributor price discounts at each reporting period to reduce accounts receivable and revenue. Although the Company accrues an estimate of distributor price discounts, the Company does not issue these discounts to the distributor until the inventory is sold to the distributors' customers. As of December 31, 2019 and 2018, the estimated price discount was $656 and $1,634, respectively. Payment terms of customers are typically 30 to 60 days after invoice date. The Company’s products are under warranty against defects in material and workmanship generally for a period of one or two years. The Company accrues for estimated warranty costs at the time of sale based on anticipated warranty claims and actual historical warranty claims experience including knowledge of specific product failures that are outside of the Company’s typical experience.

Other Revenue

Occasionally, the Company enters into license and development agreements with some of its customers and recognizes revenue from these agreements upon completion and acceptance by the customer of contract deliverables or as services are provided, depending on the terms of the arrangement. Revenue is deferred for any amounts billed or received prior to transfer of control. The Company believes the milestone method best depicts the efforts expended to transfer services to the customers under most of the Company’s development agreements. Certain contracts may include multiple performance obligations for which the Company allocates revenues to each performance obligation based on relative stand-alone selling price. The Company determines stand-alone selling prices based on observable evidence. When stand-alone selling prices are not directly observable, the Company uses the adjusted market assessment approach or residual approach, if applicable.

The Company does not disclose the value of unsatisfied performance obligations for (i) contracts with an original expected length of one year or less or (ii) contracts for which the Company recognizes revenue at the amount to which it has the right to invoice for services performed. The estimated revenue expected to be recognized in 2020 and 2021 related to performance obligations that are unsatisfied (or partially unsatisfied) as of December 31, 2019 was $12,338 and $7,790, respectively.

Revenue from non-product sales was approximately 7%, 3% and 3% of total revenue for the years ended December 31, 2019, 2018, and 2017, respectively.

The Company monitors the collectability of accounts receivable primarily through review of the accounts receivable aging. The Company’s policy is to record an allowance for doubtful accounts based on specific collection issues identified, aging of underlying receivables and historical experience of uncollectible balances.

Standard Product Warranty, Policy [Policy Text Block]

Warranty

The Company’s products are under warranty against defects in material and workmanship generally for a period of one or two years. The Company accrues for estimated warranty cost at the time of sale based on anticipated warranty claims and actual historical warranty claims experience including knowledge of specific product failures that are outside of the Company’s typical experience. The warranty obligation is determined based on product failure rates, cost of replacement and failure analysis cost. If actual warranty costs differ significantly from these estimates, adjustments may be required in the future. As of both December 31, 2019 and 2018, the warranty liability was immaterial.

Selling and Marketing [Policy Text Block]

Sales and Marketing Expense

Sales and marketing expense consists of salaries, stock-based compensation, employee benefits, travel, trade show costs, amortization of intangibles and others. The Company expenses sales and marketing costs as incurred. Advertising expenses for the years ended December 31, 2019, 2018 and 2017 were not material.

Income Tax, Policy [Policy Text Block]

Income Taxes

Deferred tax assets and liabilities are determined based on differences between financial reporting and tax bases of assets and liabilities, and are measured using the enacted tax rates and laws that will be in effect when the differences are expected to reverse. The Company recognizes the deferred income tax effects of a change in tax rates in the period of enactment. The Company must also make judgments in evaluating whether deferred tax assets will be recovered from future taxable income. To the extent that it believes that recovery is not likely, the Company must establish a valuation allowance. The carrying value of the Company’s net deferred tax asset is based on whether it is more likely than not that the Company will generate sufficient future taxable income to realize these deferred tax assets. A valuation allowance is established for deferred tax assets which the Company does not believe meet the “more likely than not” criteria. The Company’s judgments regarding future taxable income may change over time due to changes in market conditions, changes in tax laws, tax planning strategies or other factors. If the Company’s assumptions and consequently its estimates change in the future, the valuation allowance the Company has established may be increased or decreased, resulting in a material respective increase or decrease in income tax expense (benefit) and related impact on the Company’s reported net income (loss).

The Company regularly performs a comprehensive review of uncertain tax positions. An uncertain tax position represents an expected treatment of a tax position taken in a filed tax return, or planned to be taken in a future tax return or claim, which has not been reflected in measuring income tax expense for financial reporting purposes. Until these positions are sustained by the taxing authorities, the Company does not recognize the tax benefits resulting from such positions and reports the tax effects as a liability for uncertain tax positions in the consolidated financial statements. The Company recognizes potential interest and penalties on uncertain tax positions within the provision (benefit) for income taxes on the consolidated statement of income (loss).

On December 22, 2017, the Tax Cuts and Jobs Act (the “Tax Reform Act”) was signed into law. The Tax Reform Act contains significant changes to U.S. federal corporate income taxation, including a reduction of the corporate tax rate from 35% to 21% effective January 1, 2018, a one-time transition tax on deemed mandatory repatriation of accumulated earnings and profits of foreign subsidiaries in conjunction with the elimination of U.S. tax on dividend distributions from foreign subsidiaries, and a temporary 100% first-year depreciation deduction for certain capital investments. The effect of the tax law changes must be recognized in the period of enactment. As a result of the change in tax rate, the Company's deferred tax assets and liabilities were required to be remeasured to reflect their value at a lower tax rate of 21%. Staff Accounting Bulletin 118 (“SAB 118”) allows for a measurement period of up to one year after the enactment date of the new tax legislation to finalize the recording of the related tax impacts. In accordance with SAB 118, as of December 31, 2017, the Company made a provisional estimate of the remeasurement of the federal deferred tax assets and liabilities to reflect the reduced U.S. statutory corporate tax rate to 21%, the mandatory repatriation income which was fully absorbed by the U.S. net operating loss, the related valuation allowance offset, and valuation allowance release on deferred tax assets for the federal alternative minimum tax (“AMT”) credit that was made refundable by the Tax Reform Act. During 2018, the Company elected to account for global intangible low-taxed income (“GILTI”) as a period cost in the year the tax is incurred and made changes to its provisional estimates previously recorded for the mandatory repatriation upon filing of its 2017 U.S. income tax return. The change in the mandatory repatriation income was fully absorbed by the U.S. net operating loss, which is subject to valuation allowance, and resulted in no current tax liability. This measurement period adjustment had no net tax effect after the offsetting change to the valuation allowance. At December 31, 2018, the Company completed the accounting for all of the enactment-date income tax effects of the Tax Reform Act.

Earnings Per Share, Policy [Policy Text Block]

Earnings per Share

Basic earnings per share is calculated by dividing income allocable to common stockholders by the weighted average number of shares of common stock outstanding during the period. Diluted earnings per share is calculated by dividing the net income allocable to common stockholders by the weighted average number of common shares outstanding, adjusted for the effects of potentially dilutive common stock, which are comprised of stock options, restricted stock units, employee share purchase plan and the shares that could be issued upon conversion of the Company’s convertible debt. The capped call options in connection with the issuance of the convertible notes are excluded from the calculation of diluted earnings per share as their impact is always anti-dilutive.

New Accounting Pronouncements, Policy [Policy Text Block]

Recent Accounting Pronouncements

In February 2016, the Financial Accounting Standards Board (“FASB”) issued guidance that requires companies that lease assets (lessees) to recognize on the balance sheet the assets and liabilities for the rights and obligations created by leases with lease terms of more than 12 months. The FASB also issued additional updates to such guidance. For leases less than twelve months, an entity is permitted to make an accounting policy election by class of underlying asset not to recognize lease assets and lease liabilities. If a lessee makes this election, it should recognize lease expense for such leases generally on a straight-line basis over the lease term. The guidance requires entities to recognize and measure leases at the beginning of the earliest period presented using a modified retrospective approach or allows entities to initially apply the new lease standard at the adoption date and recognize a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. The Company adopted this guidance on January 1, 2019. See note 7 in the notes to consolidated financial statements for further details.

In June 2016, the FASB issued guidance which requires the credit losses related to debt securities classified as available-for sale to be presented as an allowance rather than as a write-down. The guidance also requires that an entity measure and recognize expected credit losses for financial assets held at amortized cost and replaces the incurred loss impairment methodology in current GAAP with a methodology that requires consideration of a broader range of information to estimate credit losses. This guidance is effective for the Company beginning after December 15, 2019. The adoption of this guidance is not expected to have a material impact to the Company's consolidated financial statements.

In January 2017, the FASB issued guidance to simplify the measurement of goodwill by eliminating the Step 2 impairment test. Step 2 measures a goodwill impairment loss by comparing the implied fair value of a reporting unit’s goodwill with the carrying amount of that goodwill. The guidance requires an entity to compare the fair value of a reporting unit with its carrying amount and recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value. Additionally, an entity should consider income tax effects from any tax deductible goodwill on the carrying amount of the reporting unit when measuring the goodwill impairment loss, if applicable. The guidance becomes effective for goodwill impairment tests in fiscal years beginning after December 15, 2019, though early adoption is permitted. The Company adopted this guidance on January 1, 2019. The adoption of this standard did not have a material impact on the Company’s consolidated financial statements.

In February 2018, the FASB issued guidance that allows an option to reclassify from accumulated other comprehensive income to retained earnings any stranded tax effects resulting from the Tax Cuts and Jobs Act (the "Tax Act"). The guidance will be effective for fiscal years beginning after December 15, 2018. The Company adopted this guidance on January 1, 2019. The adoption of this standard did not have a material impact on the Company’s consolidated financial statements.

In June 2018, the FASB issued guidance to eliminate the separate guidance applicable to share-based payments to nonemployees. Under the new guidance, equity-classified share-based payment awards issued to nonemployees will be measured on the grant date, instead of being remeasured through the performance completion date (generally the vesting date), as required under the current guidance. The guidance also requires recognition of compensation cost for awards with performance conditions when achievement of those conditions are probable, rather than upon their achievement. Further, the guidance eliminates the requirement to reassess the classification of nonemployee awards under the financial instruments literature upon vesting. The guidance is effective for fiscal years beginning after December 15, 2018. The Company adopted this guidance on January 1, 2019. The adoption of this standard did not have a material impact on the Company’s consolidated financial statements

In August 2018, the FASB issued guidance that eliminates certain disclosure requirements for fair value measurements for all entities, requires public entities to disclose certain new information and modifies some disclosure requirements. The new guidance will no longer require disclosure of the amount of and reasons for transfers between Level 1 and Level 2 of the fair value hierarchy, but will require disclosure of the range and weighted average used to develop significant unobservable inputs for Level 3 fair value measurements. The guidance will be effective for fiscal years beginning after December 15, 2019. The adoption of this guidance is not expected to have a material impact to the Company's consolidated financial statements.

In August 2018, the FASB issued guidance requiring a customer in a cloud computing arrangement that is a service contract to follow the internal use software guidance in Accounting Standards Codification (ASC) 350-40 to determine which implementation costs to capitalize as assets. Capitalized implementation costs are expensed over the term of the hosting arrangement beginning when the module or component of the hosting arrangement is ready for its intended use. The guidance will be effective for fiscal years beginning after December 15, 2019. The adoption of this guidance is not expected to have a material impact to the Company's consolidated financial statements.

In November 2018, the FASB issued amendments to guidance on “Collaborative Arrangements” and “Revenue from Contracts with Customers”, that require transactions in collaborative arrangements to be accounted for under “Revenue from Contracts with Customers” if the counterparty is a customer for a good or service (or bundle of goods and services) that is a distinct unit of account. The amendments also preclude entities from presenting consideration from transactions with a collaborator that is not a customer together with revenue recognized from contracts with customers. The guidance will be effective for fiscal years beginning after December 15, 2019. The adoption of this guidance is not expected to have a material impact to the Company's consolidated financial statements.

In December 2019, the FASB issued guidance that simplifies the accounting for income taxes as part of FASB's overall initiative to reduce complexity in accounting standards. Amendments include removal of certain exceptions to the general principles of ASC 740, Income Taxes, and simplification in general other areas such as accounting for a franchise tax (or similar tax) that is partially based on income. The guidance will be effective for fiscal years beginning after December 15, 2020, though early adoption is permitted. The Company is currently evaluating the impact that this new guidance will have on its consolidated financial statements.