We classify all cash and highly liquid investments with original maturities of three months or less at the date of purchase as cash and cash equivalents. Cash equivalents, which as of December 31, 2020 and 2019 consisted of U.S. denominated money market funds, totaled $23,832 and $1,307 as of December 31, 2020 and 2019, respectively.

Our investments in marketable securities are classified as available-for-sale. Available-for-sale securities are stated at fair value based on quoted market prices with unrealized holding gains or losses, net of tax, included in accumulated other comprehensive income, a component of shareholders’ equity. The cost of securities sold is based on the specific identification method.

Accounts receivable are recorded at invoiced amount and do not bear interest when recorded or accrue interest when past due. We maintain an allowance for doubtful accounts for estimated losses that may result from the inability of our customers to make required payments. At the end of each reporting period, we estimate the allowance for doubtful accounts based on an account-by-account risk analysis of outstanding receivable balances. The determination to write-off specific accounts receivable balances is made based on the likelihood of collection and past due status. Past due status is based on invoice date and terms specific to each customer.

We have capitalized licensed technology assets in other long-term assets. These assets are stated at cost and are amortized on a straight-line basis over the term of the license or the estimated life of the asset, if the license is not contractually limited, which is generally two to five years.

We evaluate the remaining useful life and recoverability of equipment and other assets, including identifiable intangible assets, whenever events or changes in circumstances indicate that the carrying amount of the assets may not be recoverable. If there is an indicator of impairment, we prepare an estimate of future, undiscounted cash flows expected to result from the use of each asset and its eventual disposition. If these cash flows are less than the carrying value of the asset, we adjust the carrying amount of the asset to its estimated fair value. We have concluded that the carrying value of our long-lived assets is recoverable as of December 31, 2020.

Goodwill is not amortized, rather it is tested, at least annually, for impairment at a reporting unit level. Impairment of goodwill is the condition that exists when the carrying amount of a reporting unit that includes goodwill exceeds its fair value. A goodwill impairment loss is recognized for the amount that the carrying amount of the reporting unit, including goodwill, exceeds its fair value, limited to the total amount of goodwill allocated to that reporting unit. If the fair value of a reporting unit exceeds the carrying amount, goodwill of the reporting unit is not considered impaired.

We evaluate impairment using the guidance set forth in FASB Accounting Standards Update No. 2017-04, Intangibles-Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment ("ASU 2017-04") which states that an entity may first assess qualitative factors to determine whether it is necessary to perform the quantitative goodwill impairment test. If determined to be necessary, the quantitative impairment test shall be used to identify goodwill impairment and measure the amount of goodwill impairment loss to be recognized. An entity has an unconditional option to bypass the qualitative assessment for any reporting unit in any period and proceed directly to the quantitative goodwill impairment test. Accordingly, we have elected to bypass the qualitative assessment and proceed directly to the quantitative goodwill impairment test. We tested goodwill for impairment under the quantitative goodwill impairment test during the fourth quarter of 2020 and concluded that goodwill was not impaired.

We warrant that our products will be free from defects in material and workmanship for a period of twelve months from delivery. Warranty repairs are guaranteed for the remainder of the original warranty period. Our warranty is limited to repairing or replacing products, or refunding the purchase price. At the end of each reporting period, we estimate a reserve for warranty returns based on historical experience and knowledge of any applicable events or transactions. The reserve for warranty returns is included in accrued liabilities in our consolidated balance sheets.

We currently sponsor a stock incentive plan that allows for issuance of employee stock options and restricted stock awards, including restricted stock units. We also have an employee stock purchase plan for all eligible employees. The fair value of share-based payment awards is expensed straight-line over the requisite service period, which is generally the vesting period, for the entire award. Additionally, any modification of an award that increases its fair value will require us to recognize additional expense.

The fair value of our stock option grants and purchase rights under our employee stock purchase plan are estimated as of the grant date using the Black-Scholes option pricing model which is affected by our estimates of the risk free interest rate, our expected dividend yield, expected term and the expected share price volatility of our common shares over the expected term. The fair value of our restricted stock awards are based on the market value of our stock on the date of grant.

On occasion, we enter into co-development arrangements with current or prospective customers to defray a portion of the research and development expenses we expect to incur in connection with our development of an IC product. As amounts become due and payable, they are offset against research and development expense on a pro-rata basis.

We account for income taxes under the asset and liability method. This approach requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of temporary differences between financial statement carrying amounts and tax bases of assets and liabilities. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date. We establish a valuation allowance to reduce deferred tax assets if it is "more likely than not" that a portion or all of the asset will not be realized in future tax returns.

An uncertain tax position represents treatment of a tax position taken in a filed tax return, or planned to be taken in a future tax return, that has not been reflected in measuring income tax expense for financial reporting purposes. Until these positions are sustained by the taxing authorities, we do not recognize the tax benefits resulting from such positions and report the tax effects for uncertain tax positions in our consolidated balance sheets.

We do not own or operate a semiconductor fabrication facility and do not have the resources to manufacture our products internally. We rely on a limited number of foundries and assembly and test vendors to produce all of our wafers and for completion of finished products. We do not have any long-term agreements with any of these suppliers. In light of these dependencies, it is reasonably possible that failure to perform by one of these suppliers could have a severe impact on our results of operations. Additionally, the concentration of these vendors within Taiwan, and the People’s Republic of China increases our risk of supply disruption due to natural disasters, economic instability, political unrest or other regional disturbances.

The markets in which we compete, or seek to compete, are subject to rapid technological change, frequent new product introductions, changing customer requirements for new products and features, and evolving industry standards. The introduction of new technologies and the emergence of new industry standards could render our products less desirable or obsolete, which could harm our business.

Financial instruments that potentially subject us to concentrations of credit risk consist of cash equivalents and accounts receivable. We limit our exposure to credit risk associated with cash equivalent balances by holding our funds in high quality, highly liquid money market accounts. We limit our exposure to credit risk associated with accounts receivable by carefully evaluating creditworthiness before offering terms to customers.

In December 2019, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update No. 2019-12, Simplifying the Accounting for Income Taxes ("ASU 2019-12"). ASU 2019-12 removes certain exceptions to the general principles in Accounting Standards Codification ("ASC") 740 and also clarifies and amends existing guidance to provide for more consistent application. ASU 2019-12 will become effective for us in the first quarter of fiscal 2021, and early adoption is permitted. We are evaluating the impact that the adoption of ASU 2019-12 will have on our financial position, results of operations and cash flows, but don't estimate the impact to be significant.

In November 2018, the FASB issued Accounting Standards Update No. 2018-18, Collaborative Arrangements: Clarifying the Interaction Between Topic 808 and Topic 606 ("ASU 2018-18"). ASU 2018-18 requires transactions in collaborative arrangements to be accounted for under ASC 606 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 amendment also precludes entities from presenting consideration from transactions with a collaborator that is not a customer together with revenue recognized from contracts with customers. ASU 2018-18 became effective for us on January 1, 2020. The adoption of ASU 2018-18 did not have a material impact on our financial position, results of operations and cash flows.