Business and Basis of Presentation	3 Months Ended
Business and Basis of Presentation	Mar. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Business and Basis of Presentation	Business and Basis of Presentation Transphorm, Inc. (“Parent”) develops gallium nitride (“GaN”) semiconductor components used in power conversion and is headquartered in Goleta, California. Parent’s wholly owned-subsidiary, Transphorm Technology, Inc., was incorporated in the State of Delaware on February 22, 2007. Throughout these notes, “the Company,” “Transphorm,” “we,” “us” and “our” refer to Parent and its direct and indirect wholly-owned subsidiaries. Transphorm Technology and its subsidiaries hold all material assets and conduct all business activities and operations of the Company. Transphorm Technology’s activities to date have been primarily performing research and development, establishing manufacturing infrastructure, market sampling, product launch, hiring personnel, and raising capital to support and expand these activities. Transphorm Japan, Inc. was established in Japan in February 2014 to secure Transphorm’s production capacity and establish a direct presence in Asian markets. Transphorm Aizu, Inc. was established in Japan to manage the financial transactions around Aizu Fujitsu Semiconductor Wafer Solution Limited, Transphorm’s non-controlling joint venture wafer fabrication facility located in Aizu Wakamatsu, Japan (“Aizu”). Transphorm Japan Epi, Inc. was established in Japan in 2019 to enable the operational capacity of the reactors held in Aizu. Change in Fiscal Year End On April 20, 2021, we changed our fiscal year from the period beginning on January 1 and ending on December 31 to the period beginning on April 1 and ending on March 31 of each year, effective immediately. Accordingly, we are filing this Transition Report on Form 10-K (this “Report”) to include audited consolidated financial information for the transition period from January 1, 2021 through March 31, 2021. Reverse Merger On February 12, 2020, our wholly-owned subsidiary, Peninsula Acquisition Sub, Inc., a corporation formed in the State of Delaware (“Acquisition Sub”), merged with and into Transphorm Technology (formerly known as Transphorm, Inc.), the corporate existence of Acquisition Sub ceased, and Transphorm Technology became our wholly-owned subsidiary (such transaction, the “Merger”). As a result of the Merger, we acquired the business of Transphorm Technology. The Merger was effective as of February 12, 2020, upon the filing of a certificate of merger with the Secretary of State of the State of Delaware. Immediately after completion of the Merger, we adopted Transphorm Technology’s former company name, “Transphorm, Inc.”, as our company name. The Merger was treated as a recapitalization and reverse acquisition for financial reporting purposes, and Transphorm Technology is considered the acquirer for accounting purposes. As a result of the Merger and the change in our business and operations, a discussion of the past financial results of our predecessor, Peninsula Acquisition Corporation, is not pertinent, and under applicable accounting principles, the historical financial results of Transphorm Technology, the accounting acquirer, prior to the Merger are considered our historical financial results. At the effective time of the Merger, (i) each share of Transphorm Technology’s common stock issued and outstanding immediately prior to the closing of the Merger was converted into the right to receive (a) 0.08289152527 shares of our common stock (in the case of shares held by accredited investors) or (b) $4.00 multiplied by 0.08289152527 (in the case of shares held by unaccredited investors), with the actual number of shares of our common stock issued to the former holders of Transphorm Technology’s common stock equal to 4,171,571, (ii) 51,680,254 shares of Transphorm Technology’s Series 1 preferred stock issued and outstanding immediately prior to the closing of the Merger were converted into 12,433,953 shares of our common stock, (iii) 38,760,190 shares of Transphorm Technology’s Series 2 preferred stock issued and outstanding immediately prior to the closing of the Merger were converted into 7,499,996 shares of our common stock, and (iv) 31,850,304 shares of Transphorm Technology’s Series 3 preferred stock issued and outstanding immediately prior to the closing of the Merger were converted into 4,000,000 shares of our common stock. As a result, 28,105,520 shares of our common stock were issued to the former holders of Transphorm Technology’s issued and outstanding capital stock after adjustments due to rounding for fractional shares. Immediately prior to the effective time of the Merger, an aggregate of 682,699 shares of our common stock, owned by the stockholders of Peninsula Acquisition Corporation prior to the Merger, were forfeited and cancelled. In addition, pursuant to the Merger Agreement, (i) options to purchase 29,703,285 shares of Transphorm Technology’s common stock issued and outstanding immediately prior to the closing of the Merger under Transphorm Technology’s 2007 Stock Plan (the “2007 Plan”) and 2015 Equity Incentive Plan (the “2015 Plan”) were assumed and converted into options to purchase 2,461,923 shares of our common stock, (ii) warrants to purchase 186,535 shares of Transphorm Technology’s common stock issued and outstanding immediately prior to the closing of the Merger were assumed, amended and converted into warrants to purchase 15,461 shares of our common stock, and (iii) Transphorm Technology’s outstanding convertible promissory note was amended to be convertible at the option of the holder, into shares of our common stock at a conversion price of $5.12 per share, with 3,076,171 being the maximum number of shares of our common stock issuable upon conversion of the convertible promissory note. As of December 31, 2020, there was $15.0 million of principal and $486 thousand of accrued and unpaid interest outstanding on the convertible promissory note. All per share and share amounts for the year ended December 31, 2019 have been retroactively adjusted to reflect the effect of the Merger. Going Concern The accompanying consolidated financial statements have been prepared assuming that the Company will continue as a going concern. As included in the accompanying consolidated financial statements, the Company has generated recurring losses from operations, sustained negative cash flows from operating activities, and has an accumulated deficit and has a working capital deficiency. These factors raise substantial doubt about the Company’s ability to continue as a going concern for the next twelve months from the issuance of these financial statements. Management plans to raise additional working capital to fund operations through the issuance of stock to investors, license of intellectual property and/or issuance of notes payable. The Company raised $1.0 million, $19.7 million and $13.6 million from the sales of common stock in March 31, 2021, February 2020 and December 2020, respectively, as described in Note 13 - Stockholders’ Equity. However, there is no assurance that the Company will be successful in raising additional capital. The ability of the Company to continue as a going concern is dependent on its ability to raise significant additional capital to fund operating losses until it is able to generate liquidity from its business operations. To the extent sufficient financing is not available, the Company may not be able to, or may be delayed in, developing its offerings and meeting its obligations. The Company will continue to evaluate its projected expenditures relative to its available cash and to evaluate financing alternatives in order to satisfy its working capital and other cash requirements. The accompanying consolidated financial statements do not reflect any adjustments that might result from the outcome of these uncertainties. Impact of COVID-19 on Our Business The COVID-19 pandemic has adversely disrupted and will further disrupt the operations at certain of our customers, partners, suppliers and other third-party providers for an uncertain period of time, including as a result of travel restrictions, adverse effects on budget planning processes, business deterioration, and/or business shutdowns, all of which has impacted our business and results of operations. Some of our customers have experienced delays in their internal development programs and design cycles with our GaN products due to the effects of COVID-19, which have led to postponements of their orders of our products and postponements of determinations that our products will be used in their designs for new products under development with corresponding delays in their market introduction and our revenues. The future impact of COVID-19 cannot be predicted with certainty and may make it more difficult or preclude us from raising additional capital, increase our costs of capital and otherwise adversely affect our business, results of operations, financial condition and liquidity.