Face amount or stated value per share of nonredeemable preferred stock (or preferred stock redeemable solely at the option of the issuer); generally not indicative of the fair market value per share.

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CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Apr. 30, 2013	Apr. 30, 2012
Income Statement [Abstract]
Revenue	$ 33,941	$ 25,921
Cost of revenue	12,248	7,516
Gross profit	21,693	18,405
Operating expenses:
Research and development	11,317	11,473
Selling, general and administrative	5,157	4,025
Total operating expenses	16,474	15,498
Income from operations	5,219	2,907
Other expense	(5)	(2)
Income before income taxes	5,214	2,905
Provision for income taxes	473	303
Net income	$ 4,741	$ 2,602
Net income per share attributable to ordinary shareholders:
Basic	$ 0.17	$ 0.08
Diluted	$ 0.16	$ 0.07
Weighted-average shares used to compute net income per share attributable to ordinary shareholders:
Basic	27,056,932	7,519,360
Diluted	29,066,062	9,031,710

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Apr. 30, 2013	Apr. 30, 2012
Cash flows from operating activities:
Net income	$ 4,741	$ 2,602
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation of property and equipment	194	176
Loss on disposal of long-lived assets	3
Amortization of other intangible assets		135
Stock-based compensation	1,606	943
Net excess income tax benefits associated with stock-based compensation	(91)
Change in value of warrants		(10)
Changes in operating assets and liabilities:
Accounts receivable	(3,314)	555
Inventories	(407)	(830)
Prepaid expenses and other current assets	521	110
Deferred tax assets	(139)	1
Other assets	(73)	22
Accounts payable	3,313	(808)
Accrued liabilities	(3,687)	319
Income taxes payable	(24)	205
Deferred revenue	573	(2,640)
Net cash provided by operating activities	3,216	780
Cash flows from investing activities:
Restricted Cash		(8)
Purchase of property and equipment	(579)	(147)
Net cash used in investing activities	(579)	(155)
Cash flows from financing activities:
Proceeds from exercise of stock options, warrants, and employee stock purchase plan withholding, net of repurchase of stock options	1,080	125
Payment for initial public offering cost	(25)
Net excess income tax benefits associated with stock-based compensation	91
Net cash provided by financing activities	1,146	125
Net increase in cash and cash equivalents	3,783	750
Cash and cash equivalents at beginning of period	100,494	58,944
Cash and cash equivalents at end of period	104,277	59,694
Supplemental disclosure of cash flow information:
Cash paid for income taxes	157	99
Supplemental disclosure of noncash investing activities:
Increase in accrued liabilities related to non-monetary assets purchases	$ 181	$ 48

Organization and Summary of Significant Accounting Policies	3 Months Ended
	Apr. 30, 2013
Accounting Policies [Abstract]
Organization and Summary of Significant Accounting Policies	1. Organization and Summary of Significant Accounting Policies *Organization* Ambarella, Inc. (the “Company”) was incorporated in the Cayman Islands on January 15, 2004. The Company is a developer of semiconductor processing solutions for video that enable high-definition video capture, sharing and display. The Company combines its processor design capabilities with its expertise in video and image processing, algorithms and software to provide a technology platform that is designed to be easily scalable across multiple applications and enable rapid and efficient product development. The Company’s system-on-a-chip, or SoC, designs fully integrate high-definition video processing, image processing, audio processing and system functions onto a single chip, delivering exceptional video and image quality, differentiated functionality and low power consumption. The Company sells its solutions to leading original design manufacturers, or ODMs, and original equipment manufacturers, or OEMs, globally. *Basis of presentation* The accompanying unaudited condensed consolidated financial statements have been prepared by the Company in accordance with the instructions to Form 10-Q pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”) and, therefore, do not include all information and notes normally provided in audited financial statements. The accounting policies are described in the “Notes to Consolidated Financial Statements” in the Annual Report on Form 10-K for the 2013 fiscal year filed with the SEC on April 4, 2013 (the “Form 10-K”) and updated, as necessary, in this Form 10-Q. The year-end condensed consolidated balance sheet data presented for comparative purposes was derived from audited financial statements, but does not include all disclosures required by generally accepted accounting principles in the United States (“U.S. GAAP”). In the opinion of management, all adjustments (consisting of normal recurring accruals and other adjustments) considered necessary for a fair presentation have been included. The results of operations for any interim period are not necessarily indicative of, nor comparable to, the results of operations for any other interim period or for a full fiscal year. These unaudited condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and related notes contained in the Form 10-K. *Basis of Consolidation* The Company’s fiscal year ends on January 31. The condensed consolidated financial statements of the Company and its subsidiaries have been prepared in conformity with U.S. GAAP. All intercompany transactions and balances have been eliminated in consolidation. *Use of Estimates* The preparation of condensed consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, and the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenue and expense during the reported periods. Actual results could differ from those estimates. On an ongoing basis, management evaluates its estimates and assumptions, including those related to (i) the collectability of accounts receivable; (ii) write down for excess and obsolete inventories; (iii) the estimated useful lives of long-lived assets; (iv) impairment of long-lived assets and financial instruments; (v) warranty obligations; (vi) the valuation of equity instruments; (vii) the realization of tax assets and estimates of tax liabilities, including reserves for uncertain tax positions; and (viii) the recognition and disclosure of contingent liabilities. These estimates and assumptions are based on historical experience and on various other factors which the Company believes to be reasonable under the circumstances. The company may engage third-party valuation specialists to assist with estimates related to the valuation of financial instruments and assets associated with various contractual arrangements, and the valuation of preference and ordinary shares. Such estimates often require the selection of appropriate valuation methodologies and significant judgment. Actual results could differ from these estimates under different assumptions or circumstances. *Concentration of Risk* The Company’s products are manufactured, assembled and tested by third-party contractors located primarily in Asia. The Company does not have long-term agreements with these contractors. A significant disruption in the operations of one or more of these contractors would impact the production of the Company’s products which could have a material adverse effect on its business, financial condition and results of operations. A substantial portion of the Company’s revenue is derived from sales through its logistics provider, Wintech Microelectronics Co., Ltd., or Wintech, which serves as the Company’s non-exclusive sales representative in all of Asia other than Japan, and through one large direct ODM customer, Chicony Electronics Co., Ltd., or Chicony. Termination of the relationships with these two customers could result in a temporary or permanent loss of revenue and obligation to repurchase unsold product. Furthermore, any credit issues from these two customers could impair their abilities to make timely payment to the Company. See Note 11 for additional information regarding concentration with these two customers. Financial instruments that potentially subject the Company to concentrations of credit risk consist primarily of cash and accounts receivable. The Company places its cash primarily in checking and money market accounts with reputable financial institutions. Deposits held with these financial institutions may exceed the amount of insurance provided on such deposits. The Company has not experienced any material losses on deposits of its cash. The Company does not hold or issue financial instruments for trading purposes. The Company performs ongoing credit evaluations of each of its customers and adjusts credit limits based upon payment history and the customer’s credit worthiness. The Company regularly monitors collections and payments from its customers. *Foreign Currency Transactions* The U.S. dollar is the functional currency for the Company and its subsidiaries. Monetary assets and liabilities denominated in non-U.S. currencies are re-measured to U.S. dollars using current exchange rates in effect at the balance sheet date. Nonmonetary assets and liabilities are re-measured to U.S. dollars using historical exchange rates. Monetary and other accounts are re-measured to U.S. dollars using average exchange rates in effect during each period. Gains or losses from foreign currency remeasurement are included in other expense in the condensed consolidated statements of operations, and, to date, have not been material. *Cash, Cash Equivalents and Short-Term Investments* The Company considers all highly liquid investments with maturities of less than three months at the time of purchase to be cash equivalents. Investments with maturities at the time of acquisition greater than three months are classified as short-term investments as these are considered as available-for-sale in current operations. There were no cash equivalents or short-term investments as of April 30, 2013 and January 31, 2013, respectively. *Cost Method Investment* The Company accounts for its investment in a privately held company under the cost method and reports the investment in other assets in the condensed consolidated balance sheets. The Company monitors the carrying value of the investment and records a reduction in carrying value when a decline in value is deemed to be other than temporary. To date, the Company has not recognized any impairment losses related to this investment. *Trade Accounts Receivable and Allowances for Doubtful Accounts* Trade accounts receivable are recorded at the invoiced amount and do not include finance charges. The Company performs ongoing credit evaluation of its customers and generally requires no collateral. The Company assesses the need for allowances for doubtful accounts for estimated losses resulting from the inability of its customers to make required payments by considering factors such as historical collection experience, credit quality, aging of the accounts receivable balances and current economic conditions that may affect a customer’s ability to pay. There were no write-offs of accounts receivable for the three months ended April 30, 2013 and 2012, respectively. There was no allowance for doubtful accounts recorded as of April 30, 2013 and January 31, 2013, respectively. *Fair Market Value of Financial Instruments* The carrying amounts reflected in the condensed consolidated balance sheets for cash, accounts receivable, accounts payable, accrued liabilities and other current liabilities, approximate fair value due to the short-term nature. The fair value of outstanding warrants to purchase redeemable convertible preference shares converted into warrants to purchase ordinary shares is described in Note 6. *Inventories* The Company records inventories at the lower of cost or market. The cost includes materials and other production costs and is computed using standard cost on a first-in, first-out basis. Inventory reserves are recorded for estimated obsolescence or unmarketable inventories based on forecast of future demand and market conditions. If actual market conditions are less favorable than projected, or if future demand for the Company’s products decrease, additional inventory write-downs may be required. Once inventory is written down, a new accounting basis has been established and, accordingly, any associated reserve is not reversed until the inventory sold or scrapped. The Company has not recognized any material inventory loss to date. *Property and Equipment* Property and equipment are stated at cost and depreciated using the straight-line method over the estimated useful life of three years for computer equipment, computer software, machinery, equipment and furniture and fixtures. Leasehold improvements are amortized over the shorter of the lease term or their estimated useful lives. Repairs and maintenance are charged to expense as incurred. *Intangible Assets* Technology licenses purchased from third parties and that can be used in alternative research and development projects are capitalized as intangible assets. Capitalized costs are amortized over an estimated economic useful life under a straight-line method and recorded as research and development expenses. *Impairment of Long-Lived Assets* The Company records long-lived assets at cost and evaluates them for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Events or changes in circumstances that may indicate that an asset is impaired include significant decreases in the market value of an asset, significant underperformance relative to expected historical or projected future results of operations, a change in the extent or manner in which an asset is utilized, significant declines in the estimated fair value of the overall Company for a sustained period, shifts in technology, loss of key management or personnel, changes in the Company’s operating model or strategy and competitive forces. When the sum of the expected future undiscounted cash flows expected to be generated by the related asset group is less than its carrying amount, an impairment loss would be recognized. Should impairment exist, the impairment loss would be measured based on the excess of the carrying amount of the asset over the asset’s estimated fair value. There has been no occurrence of events to date that would trigger an impairment analysis. As such, no impairment charge has been recognized as of April 30, 2013. *Revenue Recognition* The Company generates revenue from the sale of its SoCs to OEMs or ODMs, either directly or through logistics providers. Revenue from sales directly to OEMs and ODMs is recognized upon shipment provided persuasive evidence of an arrangement exists, legal title to the products and risk of ownership have transferred, the fee is fixed or determinable, and collection of the resulting receivable is reasonably assured. The Company provides its logistics providers with the right to return excess levels of inventory and to future price adjustments. Given the inability to reasonably estimate these price changes and returns, revenue and costs related to shipments to logistics providers are deferred until the Company has received notification from its logistics providers that they have sold the Company’s products. Information reported by the Company’s logistics providers includes product resale price, quantity and end customer shipment information as well as remaining inventory on hand. At the time of shipment to a logistics provider, the Company records a trade receivable as there is a legally enforceable right to receive payment, reduces inventory for the value of goods shipped as legal title has passed to the logistics provider and defers the related margin as deferred revenue in the condensed consolidated balance sheets. Any price adjustments are recorded as a reduction to deferred revenue at the time the adjustments are agreed upon. Arrangements with certain OEM customers provide for pricing that is dependent upon the end products into which the Company’s SoCs are used. These arrangements may also entitle the Company to a share of the product margin ultimately realized by the OEM. The minimum guaranteed amount of revenue related to the sale of products subject to these arrangements is recognized when all other elements of revenue recognition are met. Any amounts at the date of shipment invoiced in excess of the minimum guaranteed contract price are deferred until the additional amounts the Company is entitled to are fixed or determinable. Additional amounts earned by the Company resulting from margin sharing arrangements and determination of the end products into which the products are ultimately incorporated are recognized when end customer sales volume is reported to the Company. The Company also sells a limited amount of software under perpetual licenses that include post-contract customer support, or PCS. The Company does not have evidence of fair value for the PCS and, accordingly, license revenue is recognized ratably over the estimated supporting period in accordance with ASC 985, Software Revenue Recognition. The revenue from those licenses comprised 1% and 3% of the Company’s total revenue for the three months ended April 30, 2013 and 2012, respectively. *Cost of Revenue* Cost of revenue includes cost of materials, cost associated with packaging and assembly, testing and shipping, cost of personnel, stock-based compensation, logistics and quality assurance, warranty cost, royalty expense, write-downs of inventories and allocation of overhead. *Warranty Costs* The Company typically provides warranty on its products. The Company accrues for the estimated warranty costs at the time when revenue is recognized. The warranty accruals are regularly monitored by management based upon historical experience and any specifically identified failures. While the Company engages in extensive product quality assessment, actual product failure rates, material usage or service delivery costs could differ from estimates and revisions to the estimated warranty liability would be required. The Company’s warranty accruals have not been material to date. *Research and Development* Research and development costs are expensed as incurred and consist primarily of personnel costs, product development costs, which include engineering services, development software and hardware tools, license fees, cost of fabrication of masks for prototype products, other development materials costs, depreciation of equipment used in research and development and allocation of facilities costs. *Selling, General and Administrative* Selling, general and administrative expense consists of personnel costs, travel and trade show costs, legal expenses, other professional services and occupancy costs. Advertising expenses have not been material to date. *Operating Leases* The Company recognizes rent expense on a straight-line basis over the term of the lease. The difference between rent expense and rent paid is recorded as deferred rent and is included in accrued liabilities in the condensed consolidated balance sheets. *Income Taxes* The Company records income taxes using the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been recognized in its financial statements or tax returns. In estimating future tax consequences, generally all expected future events other than enactments or changes in the tax law or rates are considered. Valuation allowances are provided when necessary to reduce deferred tax assets to the amount expected to be realized. The Company applies authoritative guidance for the accounting for uncertainty in income taxes. The guidance requires that tax effects of a position be recognized only if it is “more likely than not” to be sustained based solely on its technical merits as of the reporting date. Upon estimating the Company’s tax positions and tax benefits, the Company considered and evaluated numerous factors, which may require periodic adjustments and which may not reflect the final tax liabilities. The Company adjusts its financial statements to reflect only those tax positions that are more likely than not to be sustained under examination. As part of the process of preparing condensed consolidated financial statements, the Company is required to estimate its taxes in each of the jurisdictions in which it operates. The Company estimates actual current tax exposure together with assessing temporary differences resulting from differing treatment of items, such as accruals and allowances not currently deductible for tax purposes. These differences result in deferred tax assets, which are included in the condensed consolidated balance sheets. In general, deferred tax assets represent future tax benefits to be received when certain expenses previously recognized in the condensed consolidated statements of operations become deductible expenses under applicable income tax laws, or loss or credit carryforwards are utilized. In assessing whether deferred tax assets may be realized, management considers whether it is more likely than not that some portion or all of deferred tax assets will be realized. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income. The Company makes estimates and judgments about its future taxable income based on assumptions that are consistent with its plans and estimates. Should the actual amounts differ from estimates, the amount of valuation allowance could be materially impacted. Any adjustment to the deferred tax asset valuation allowance would be recorded in the income statement for the periods in which the adjustment is determined to be required. *Stock-Based Compensation* The Company measures stock-based compensation for equity awards granted to employees and directors based on the estimated fair value on the grant date, and recognizes that compensation as expense using the straight-line attribution method for service condition awards or using the graded-vesting attribution method for awards with performance conditions over the requisite service period, which is typically the vesting period of each award. The Company estimates the fair value of awards of restricted stock units, or RSUs, based on the fair market value of its ordinary shares on the date of grant. The Company uses the Black-Scholes option pricing model to determine the fair value of stock option grants and shares issuance pursuant to its employee stock purchase plan, or ESPP. Determining the fair value of stock option awards on the grant date or the fair value of ESPP shares on the offering date requires the input of various assumptions, including stock price of the underlying ordinary share, the exercise price of the stock option or the offering price of the ESPP share, expected volatility, expected term, risk-free interest rate and dividend rate. The expected term for stock option is calculated using the simplified method as prescribed by the guidance provided by the Securities and Exchange Commission, as neither relevant historical experience nor other relevant data are available to estimate future exercise behavior. The expected term for shares issuance pursuant to the ESPP is the offering period. The expected volatility is based on the historical volatilities of similar companies whose share prices are publicly available for a period commensurate with the expected term. The risk-free interest rate is derived from the average U.S. Treasury constant maturity rates during the respective periods commensurate with the expected term. The expected dividend yield is zero because the Company has not historically paid dividends and has no present intention to pay dividends. The Company uses historical data to estimate pre-vesting award forfeitures and records stock-based compensation only for those awards that are expected to vest. Forfeitures are estimated at the time of grant and revised if necessary in subsequent periods if actual forfeitures differ from estimates. The Company recognizes non-employee stock-based compensation expense based on the estimated fair value of the equity instrument determined by the Black-Scholes option pricing model. The fair value of the non-employee awards is remeasured at each reporting period until services required under the arrangement are completed, which is the vesting date. Prior to the initial public offering, or IPO, the Company engaged an independent appraiser to assist in the valuation of its ordinary share price. The board of directors directed these regular valuations and had input into determining the relevant objective and subjective factors accounted for and relevant approaches in each valuation. After the IPO, the exercise price of stock option awards is determined based on the closing price of the Company’s ordinary shares traded on NASDAQ on the grant date. *Net Income Per Ordinary Share* The Company applies the two-class method to calculate and present net income per ordinary share. Under the two-class method, net income is allocated between ordinary shares and other participating securities based on their participating rights. Participating securities are defined as securities that may participate in undistributed earnings with ordinary shares, whether that participation is conditioned upon the occurrence of a specified event or not. Basic net income per ordinary share is computed by dividing net income allocable to ordinary shares by the weighted-average number of ordinary shares outstanding for the period. Diluted net income per ordinary share is computed by dividing net income allocable to ordinary shares and income allocable to participating securities, to the extent they are dilutive, by the weighted-average number of ordinary shares outstanding, including the dilutive effects of participating securities on an if-converted basis plus the dilutive effects of ordinary shares. The Company’s potential dilutive ordinary share equivalents consist of incremental ordinary shares issuable upon the exercise of options, upon the issuance of shares pursuant to the ESPP, upon the release of vested restricted stock units, upon the conversion of its redeemable convertible preference shares and upon the exercise of warrants. The Company performs an assessment as to whether instruments granted in stock-based payment transactions are participating securities. Stock-based payment awards that have not yet vested meet the definition of a participating security provided the right to receive the dividend is non-forfeitable and non-contingent. These participating securities should be included in the computation of basic net income per share under the two-class method. The Company has concluded that its non-vested early-exercised options meet the definition of a participating security and should be included in the Company’s computation of basic earnings per ordinary share. *Comprehensive Income* There are no differences between comprehensive income as defined by ASC 220, Comprehensive Income, and net income as reported in the Company’s condensed consolidated statements of operations. *Recent Accounting Pronouncements* In February 2013, the FASB issued ASU No. 2013-02, Reporting of Amounts Reclassified Out of Accumulated Other Comprehensive Income (“AOCI”). This new guidance requires that the Company present either in a single note or parenthetically on the face of the financial statements, the effect of significant amounts reclassified from each component of accumulated other comprehensive income based on its source and the income statement line items affected by the reclassification. If a component is not required to be reclassified to net income in its entirety, the Company would instead cross reference to the related footnote for additional information. This guidance only impacts disclosures within the Company’s consolidated financial statements and notes to the consolidated financial statements and does not result in a change to the accounting treatment of AOCI. This new guidance became effective prospectively for fiscal years, and interim periods with those years, beginning after December 15, 2012. The Company adopted this guidance and the adoption did not have an impact on its financial position, results of operations or disclosures.

The entire disclosure for the organization, consolidation and basis of presentation of financial statements disclosure, and significant accounting policies of the reporting entity. May be provided in more than one note to the financial statements, as long as users are provided with an understanding of (1) the significant judgments and assumptions made by an enterprise in determining whether it must consolidate a VIE and/or disclose information about its involvement with a VIE, (2) the nature of restrictions on a consolidated VIE's assets reported by an enterprise in its statement of financial position, including the carrying amounts of such assets, (3) the nature of, and changes in, the risks associated with an enterprise's involvement with the VIE, and (4) how an enterprise's involvement with the VIE affects the enterprise's financial position, financial performance, and cash flows. Describes procedure if disclosures are provided in more than one note to the financial statements.

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Inventories

3 Months Ended

Apr. 30, 2013

Inventory Disclosure [Abstract]

Inventories

2. Inventories

Inventory at April 30, 2013 and January 31, 2013 consisted of the following:


	As of April 30, 2013		As of January 31, 2013
	(in thousands)

Work-in-progress	$	4,845	$	4,044
Finished goods		4,480		4,874


Total	$	9,325	$	8,918

Property Plant And Equipment [Abstract]

The entire disclosure for inventory. This may include, but is not limited to, the basis of stating inventory, the method of determining inventory cost, the major classes of inventory, and the nature of the cost elements included in inventory. If inventory is stated above cost, accrued net losses on firm purchase commitments for inventory and losses resulting from valuing inventory at the lower-of-cost-or-market may also be included. For LIFO inventory, may disclose the amount and basis for determining the excess of replacement or current cost over stated LIFO value and the effects of a LIFO quantities liquidation that impacts net income.

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Property and Equipment, Net

3 Months Ended

Apr. 30, 2013

Property and Equipment, Net

3. Property and Equipment, Net

Depreciation expense was approximately $0.2 million for the three months ended April 30, 2013 and 2012, respectively. Property and equipment at April 30, 2013 and January 31, 2013 consisted of the following:


	As of April 30, 2013			As of January 31, 2013
	(in thousands)

Computer equipment and software	$	2,867		$	2,810
Machinery and equipment		2,063			2,050
Furniture and fixtures		397			397
Leasehold improvements		642			642
Construction in progress		1,370			827

		7,339			6,726

Less: accumulated depreciation and amortization		(4,363	)		(4,190	)


Total property and equipment, net	$	2,976		$	2,536

The entire disclosure for long-lived, physical assets that are used in the normal conduct of business to produce goods and services and not intended for resale. Examples include land, buildings, machinery and equipment, and other types of furniture and equipment including, but not limited to, office equipment, furniture and fixtures, and computer equipment and software. This disclosure may include property plant and equipment accounting policies and methodology, a schedule of property, plant and equipment gross, additions, deletions, transfers and other changes, depreciation, depletion and amortization expense, net, accumulated depreciation, depletion and amortization expense and useful lives, income statement disclosures, assets held for sale and public utility disclosures.

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Accrued Liabilities

3 Months Ended

Apr. 30, 2013

Deferred Revenue and Deferred Cost

Accrued Liabilities

4. Accrued Liabilities

Accrued liabilities at April 30, 2013 and January 31, 2013 consisted of the following:


	As of April 30, 2013		As of January 31, 2013
	(in thousands)

Accrued employee compensation	$	5,259	$	8,599
Refundable exercised unvested options		161		210
Accrued warranty		335		352
Accrued rebates		192		272
Accrued product development costs		3,920		2,875
Other accrued liabilities		1,317		2,111


Total accrued liabilities	$	11,184	$	14,419

Deferred Revenue and Deferred Cost

3 Months Ended

Apr. 30, 2013

Revenue Recognition [Abstract]

5. Deferred Revenue and Deferred Cost

Deferred revenue and related cost at April 30, 2013 and January 31, 2013 consisted of the following:


	As of April 30, 2013			As of January 31, 2013
	(in thousands)

Deferred revenue on product shipments	$	5,051		$	3,827
Deferred revenue from licenses		300			485
Deferred cost of revenue on product shipments		(1,327	)		(861	)


Total deferred income	$	4,024		$	3,451

Capital Stock

3 Months Ended

Apr. 30, 2013

Compensation And Retirement Disclosure [Abstract]

Capital Stock

6. Capital Stock

Preference shares

After completion of the IPO, a total of 20,000,000 preference shares, with a $0.00045 par value per share, were authorized. There were no shares issued and outstanding as of April 30, 2013 and January 31, 2013, respectively.

Warrants

In connection with a financing agreement in 2004, the Company issued warrants to purchase 36,292 Series B redeemable convertible preference shares at an exercise price of $3.582 per share. The warrants are fully vested and are exercisable through December 2014.

In June 2005, the FASB issued authoritative guidance on the classification of freestanding warrants and other similar instruments on shares that are redeemable (either puttable or mandatorily redeemable). The guidance requires liability classification for warrants issued that are exercisable into convertible preferred stock. Liability classification requires the warrants to be remeasured to their fair value for each reporting period.

Prior to the closing of IPO, the Company utilized the Black-Scholes option pricing model to determine the fair value of the warrants to purchase redeemable convertible preference shares, including the consideration of underlying ordinary share price, a risk-free interest rate, the expected term and expected volatilities. The warrants were revalued up to the closing of IPO and any change in fair value has been recorded in other expense.

Upon the completion of the IPO, the warrants to purchase redeemable convertible preference shares converted to warrants to purchase ordinary shares. During the three months ended April 30, 2013, a total of 25,125 warrants were exercised. A total of 11,167 and 36,292 warrants were outstanding at April 30, 2013 and January 31, 2013, respectively.

Ordinary shares

At April 30, 2013 and January 31, 2013, a total of 200,000,000 ordinary shares were authorized. As of April 30, 2013 and January 31, 2013, the following ordinary shares were reserved for future issuance:


	As of April 30, 2013		As of January 31, 2013

Shares reserved for options and restricted stock units		6,836,469		5,818,126
Shares reserved for employee stock purchase plan		798,383		460,445
Shares reserved for warrants		11,167		36,292

Employee Benefits and Stock-based Compensation

3 Months Ended

Apr. 30, 2013

Employee Benefits and Stock-based Compensation

7. Employee Benefits and Stock-based Compensation

401(k) Plan

The Company maintains a defined contribution 401(k) plan (the “401(k) Plan”) for all of its eligible U.S. employees. Under the 401(k) Plan, eligible employees may contribute up to the Internal Revenue Service annual contribution limitation. The Company is responsible for administrative costs of the Plan. The Company has not had any matching contributions to date.

Stock Option Plans

2004 Stock Plan. The board of directors adopted, and the shareholders approved, the 2004 Stock Plan, as amended, (the “2004 Plan”). The 2004 Plan was last amended on August 28, 2012. The 2004 Plan provides for the grant of incentive stock options (“ISOs”) within the meaning of Section 422 of the Internal Revenue Code of 1986, as amended (the “Code”), nonstatutory stock options (“NSOs”), stock purchase rights to acquire restricted stock and restricted stock units. Upon the completion of the IPO, no additional awards will be granted under the 2004 Plan and the 2004 Plan was terminated. However, all outstanding stock options and other awards previously granted under the 2004 Plan will remain subject to the terms of the 2004 Plan.

2012 Equity Incentive Plan. The board of directors has adopted, and the shareholders have approved, the 2012 Equity Incentive Plan, (the “EIP”). The EIP became effective on October 8, 2012. The EIP permits the grant of ISOs, within the meaning of Section 422 of the Code, to employees of the Company and any of the Company’s subsidiary corporations, and the grant of NSOs, stock appreciation rights, restricted stock, restricted stock units, performance units, performance shares, deferred stock units and dividend equivalents to employees, directors and consultants of the Company and any of the Company’s subsidiary corporations’ employees and consultants.

The exercise price of ISOs granted to a holder of more than 10% of the voting power of all classes of the Company’s shares shall be no less than 110% of the estimated fair market value on the grant date. The exercise price of ISOs granted to other employees and NSOs shall be no less than 100% of estimated fair market value on the grant date. Options granted under the Plans have a term of up to 10 years from grant date. Options granted to new employees generally vest 25% on the first anniversary date of the grant and the remainder ratably over the following 36 months. Vesting schedules for other grants to employees vary and are subject to approval by the board of directors.

The fair value of restricted stock units, or RSUs, is determined on the grant date. Prior to the Company’s IPO, 1/16th of the RSUs were to vest each three months following the vesting commencement date, so as to be 100% vested on the fourth anniversary of the vesting commencement date (the “Time-Based Vesting Schedule”); provided, however, that the RSUs did not vest at all until a Liquidity Event has occurred, at which time the Time-Based Vesting Schedule would apply, subject to the RSU holder continuing to provide services to the Company through such vesting dates. For purpose of those RSUs, “Liquidity Event” means either (i) the expiration of the lock-up period that commenced on October 10, 2012 and ended on April 8, 2013 applicable in connection with the Company’s IPO, or (ii) a change in control of the Company. After the Company’s IPO, RSUs granted to new employees generally vest 25% on the first anniversary of the vesting commencement date and 1/16th of the RSUs vest each 3 months thereafter. Vesting schedules for other RSUs to employees vary and are subject to approval by the board of directors.

2012 Employee Stock Purchase Plan. The board of directors has adopted, and the shareholders have approved, the 2012 Employee Stock Purchase Plan, or ESPP, which became effective upon the completion of IPO. The ESPP permits eligible participants to purchase ordinary shares at a discount through contributions of up to 10% of their eligible compensation, subject to any IRS limitations. The ESPP provides for offering and purchase periods of six months in duration, except for the first offering period that commenced on the occurrence of the IPO and will end on September 16, 2013. The purchase price of ordinary shares is 85% of the lower of the closing market price of the Company’s ordinary shares on the first trading day of each offering period or on the purchase date.

Early exercise rights. Certain employees have the right to early exercise unvested options, subject to repurchase rights held by the Company at their original purchase price upon termination of employment until vested. As of April 30, 2013 and January 31, 2013, a total of 86,005 and 84,377 shares of unvested early exercised options were repurchased, respectively. There were 39,242 and 53,151 unvested shares subject to the Company’s repurchase rights as of April 30, 2013 and January 31, 2013, respectively.

Stock-based Compensation

The following table presents the classification of stock-based compensation for the periods indicated:


	Three Months Ended April 30,
	2013		2012
	(in thousands)
Stock-based compensation:
Cost of revenue	$	34	$	14
Research and development		974		532
Selling, general and administrative		598		397


Total stock-based compensation	$	1,606	$	943

As of April 30, 2013, total unrecognized compensation cost related to unvested stock options and unvested restricted stock units was $6.7 million and $2.0 million, respectively, and is expected to be recognized over a weighted-average period of 2.15 years and 1.83 years, respectively. As of January 31, 2013, total unrecognized compensation cost related to unvested stock options and unvested restricted stock units was $7.3 million and $2.4 million, respectively, and is expected to be recognized over a weighted-average period of 2.26 years and 1.77 years, respectively.

The income tax benefit on stock-based compensation recognized for the three months ended April 30, 2013 and 2012 was not material.

The following table sets forth the weighted-average assumptions used to estimate the fair value of the stock options for the periods indicated:


	Three Months Ended April 30,
	2013			2012
Stock Options:
Volatility		65	%		66	%
Risk-free interest rate		1.17	%		1.10	%
Expected term (years)		6.05			6.05
Dividend yield		0	%		0	%

The following table summarizes stock option activities for the three months ended April 30, 2013:


	Option Outstanding
	Shares			Weighted- Average Exercise Price		Weighted- Average Grant-date Fair Value		Total Intrinsic Value of options Exercised (in thousands)		Weighted- Average Remaining Contractual Term (in years)		Aggregate Intrinsic Value (in thousands)

Outstanding at January 31, 2013		4,344,535			6.07
Granted		60,000			13.74	$	8.15
Exercised		(158,871	)		3.11			$	1,689
Forfeited		(31,561	)		8.45


Outstanding at April 30, 2013		4,214,103			6.27						6.67	$	31,311

Exercisable at April 30, 2013		3,084,125			5.42						6.07	$	25,522

Vested and expected to vest at April 30, 2013		4,140,490			6.23						6.64	$	30,940

Exercisable shares include options with early exercise rights. The vested and expected-to-vest options are calculated based on vesting schedule of each grant as of the reporting date.

The intrinsic value of options outstanding, exercisable and vested and expected-to-vest are calculated based on the difference between the fair market value of the Company’s ordinary shares on the reporting date and the exercise price. The closing price of the Company’s ordinary shares was $13.70 on April 30, 2013, as reported by the NASDAQ Global Market. The intrinsic value of exercised options is calculated based on the difference between the fair market value of the Company’s ordinary shares on the exercise date and the exercise price.

The following table summarizes restricted stock units activities for the three months ended April 30, 2013:


	Shares			Weighted- Average Grant-Date Fair Value
Unvested at January 31, 2013		339,217		$	9.99
Granted		11,000			13.74
Released		(39,364	)		9.99
Forfeited		(5,464	)		9.99


Unvested at April 30, 2013		305,389		$	10.13

As of April 30, 2013, the aggregate intrinsic value of unvested restricted stock units was $4.2 million.

Non-employee Stock-based Compensation

The fair value of awards granted to non-employees is determined on the date of grant and remeasured at the end of each reporting period until such awards vest. The non-employee stock-based compensation was not material for the three months ended April 30, 2013 and 2012, respectively.

Net Income Per Ordinary Share

3 Months Ended

Apr. 30, 2013

Earnings Per Share [Abstract]

Net Income Per Ordinary Share

8. Net Income Per Ordinary Share

The following table sets forth the computation of basic and diluted net income per ordinary share for the periods indicated:


	Three Months Ended April 30,
	2013			2012
	(in thousands, except share and per share data)
Numerator:
Net income	$	4,741		$	2,602
Less: amount allocable to preference shareholders		—			(2,028	)
Less: amount allocable to unvested early exercised options		(9	)		(8	)


Net income allocable to ordinary shareholders - basic	$	4,732		$	566


Undistributed earnings reallocated to ordinary shareholders		1			68


Net income allocable to ordinary shareholders - diluted	$	4,733		$	634


Denominator:
Weighted-average ordinary shares outstanding		27,103,129			7,622,621
Less: weighted-average unvested early exercised options subject to repurchase		(46,197	)		(103,261	)


Weighted-average ordinary shares - basic		27,056,932			7,519,360


Effect of potentially dilutive securities:
Employee stock options		1,688,768			1,512,350
Restricted stock units		141,647			—
Employee stock purchase plan		170,817			—
Warrants to purchase ordinary shares		7,898			—

Weighted-average ordinary shares - diluted		29,066,062			9,031,710


Net income per ordinary share:
Basic	$	0.17		$	0.08


Diluted	$	0.16		$	0.07

Earnings per share (“EPS”) of ordinary shares was calculated using the two-class method required for participating securities. Prior to the date of the IPO, all series of redeemable convertible preference shares were considered to be participating securities due to their non-cumulative dividend rights. In connection with the Company’s IPO in October 2012, all outstanding redeemable convertible preference shares converted to ordinary shares. Net income has been allocated to the ordinary shares, redeemable convertible preference shares and unvested early exercised options based on their respective rights to share in net income and weighted-average outstanding during the periods.

The following weighted-average potentially dilutive securities were excluded from the computation of diluted net income per ordinary share as their effect would have been antidilutive:


	Three Months Ended April 30,
	2013		2012

Options to purchase ordinary shares		390,928		2,046,941
Restricted stock units		6,303		—
Employee stock purchase plan		—		—
Early exercised options subject to repurchase		46,197		103,261
Redeemable convertible preference shares (if-converted basis)		—		13,315,727
Warrants to purchase redeemable convertible preference shares (if-converted basis)		—		36,292
Warrants to purchase ordinary shares		—		—


		443,428		15,502,221

The entire disclosure for earnings per share.

+ References+ Details

Income Taxes

3 Months Ended

Apr. 30, 2013

Income Tax Disclosure [Abstract]

Income Taxes

9. Income Taxes

The Company reported the following income tax for the periods indicated:


	Three Months Ended April 30,
	2013		2012
	(in thousands)
Income tax expense	$	473	$	303

The Company recognized income tax expense of approximately $0.5 million and $0.3 million for the three months ended April 30, 2013 and 2012, respectively. The estimated effective tax rate was 9.1% and 10.4% for the three months ended April 30, 2013 and 2012, respectively. The effective tax rate for the three months ended April 30, 2013 was lower than the effective tax rate for the three months ended April 30, 2012 primarily due to tax benefits resulting from the reinstatement of the U.S. federal research credit in January 2013.

The Company files federal and state income tax returns in the United States and in various foreign jurisdictions. The tax years 2007 to 2009 and 2011 to 2013 remain open to examination by U.S. federal tax authorities. The tax years 2004 to 2013 remain open to examination by U.S. state tax authorities. The tax years 2010 to 2013 remain open to examination by material foreign tax authorities.

The Company regularly assesses the likelihood of adverse outcomes resulting from these examinations to determine the adequacy of its provision for income taxes. These assessments can require considerable estimates and judgments. As of April 30, 2013, the gross amount of unrecognized tax benefits was approximately $3 million. If the estimates of income tax liabilities prove to be less than the ultimate assessment, then a further charge to expense would be required. If events occur and the payment of these amounts ultimately proves to be unnecessary, the reversal of the liabilities would result in tax benefits being recognized in the period in which the Company determines the liabilities are no longer necessary. The Company does not anticipate any material changes to its uncertain tax positions during the next twelve months.

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

Commitments And Contingencies Disclosure [Abstract]

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+ Details

Commitments and Contingencies

3 Months Ended

Apr. 30, 2013

Commitments and Contingencies

10. Commitments and Contingencies

The Company leases its principal facilities and time-based software licenses under operating agreements with various expiration dates through February 2018. In March 2013, the Company entered into a lease agreement for approximately 35,000 square feet for its new Santa Clara, California headquarters. The lease has an initial five-year term and terminates in April 2018. The monthly basic rent obligation for this facility initially will be approximately $44,550, increasing annually to approximately $65,400 in 2017. The average monthly basic rent expense over the term of the lease will be approximately $59,800. Net rental expenses for the three months ended April 30, 2013 and 2012 were approximately $1.1 million for both periods. Future annual minimum lease payments under these operating leases with initial lease terms in excess of one year are as follows:


	As of April 30, 2013
Fiscal Year	(in thousands)
2014	$	2,718
2015		1,498
2016		1,346
2017		933
2018		955


	$	7,450

Contract Manufacturer Commitments

The Company’s components and products are procured and built by independent contract manufacturers based on sales forecasts. These forecasts include estimates of future demand, historical trends, analysis of sales and marketing activities, and adjustment of overall market conditions. The Company regularly issues purchase orders to independent contract manufacturers which are cancelable only upon the agreement between the Company and the third-party. As of April 30, 2013 and January 31, 2013, total manufacturing purchase commitments were approximately $13.1 million and $15.1 million, respectively.

Indemnification

The Company, from time to time, in the normal course of business, indemnifies certain vendors with whom it enters into contractual relationships. The Company has agreed to hold the other party harmless against third-party claims in connection with the Company’s future products. The Company also indemnifies certain customers against third party claims related to certain intellectual property matters. It is not possible to determine the maximum potential amount of liability under these indemnification obligations due to the limited history of prior indemnification claims and the unique facts and circumstances that are likely to be involved in each particular claim. The Company has not made payments under these obligations and no liabilities have been recorded for these obligations on the condensed consolidated balance sheets as of April 30, 2013 and January 31, 2013.

The entire disclosure for commitments and contingencies.

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+ Details

Segment Reporting

3 Months Ended

Apr. 30, 2013

Segment Reporting [Abstract]

Segment Reporting

11. Segment Reporting

The Company operates in one reportable segment related to the development and sales of low-power, high-definition video products. The Chief Executive Officer of the Company has been identified as the Chief Operating Decision Maker (the “CODM”) and manages the Company’s operations as a whole and for the purpose of evaluating financial performance and allocating resources, the CODM reviews financial information presented on a consolidated basis accompanied by information by customer and geographic region.

Geographic Revenue

The following table sets forth the Company’s revenue by geographic region for the periods indicated:


	Three Months Ended April 30,
	2013		2012
	(in thousands)
Hong Kong	$	28,774	$	21,200
Asia Pacific		256		177
United States		2,605		3,036
North America		962		320
Europe		1,344		1,188


Total revenue	$	33,941	$	25,921

As of April 30, 2013, substantially all of the Company’s long-lived tangible assets are located in the Asia Pacific region.

Major Customers

The customers representing 10% or more of revenue and accounts receivable were customer A, a logistic provider, and customer B, a direct ODM customer, that combined accounted for approximately 82% of total revenue for the three months ended April 30, 2013. The customer representing 10% or more of revenue and accounts receivable for the three months ended April 30, 2012 was only customer A, a logistic provider, which accounted for approximately 75% of total revenue. Accounts receivable with these two customers combined accounted for approximately $21.7 million and $17.6 million as of April 30, 2013 and January 31, 2013, respectively.

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

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+ Details

Related-Party Transactions	3 Months Ended
Related-Party Transactions	Apr. 30, 2013
Related Party Transactions [Abstract]
Related-Party Transactions	12. Related-Party Transactions The Company considers an entity to be a related party if it owns more than 10% of its total voting stock at the end of each reporting period or if an officer or employee of an entity also serves on the board of directors or if it is a significant shareholder and has material business transactions with the Company. Starting from the fiscal year 2008, the Company entered into several software license agreements with Cadence Design Systems, Inc. (“Cadence”). A member of the Company’s board of directors is also the Chief Executive Officer, President and a Director of Cadence. Under these license agreements, the Company committed to pay an aggregate amount of $10.2 million payable through January 2014. The Company paid $0.4 million and $0.5 million in license fees for the three months ended April 30, 2013 and 2012, respectively. Operating lease expenses related to these agreements included in research and development cost were approximately $0.4 million for the three months ended April 30, 2013 and 2012, respectively. In addition to the related party transactions noted above, the Company recognized revenue from sales to Wintech Microelectronics Co., Ltd, or Wintech, the Company’s logistics provider. Wintech, along with an affiliate, is a shareholder of the Company owning approximately 4.6% of the voting stock as of January 31, 2013. The Company recognized revenue from sales to Wintech of approximately $13.4 million and $19.4 million for the three months ended April 30, 2013 and 2012, respectively. As of April 30, 2013 and January 31, 2013, the Company had receivables from Wintech of approximately $7.6 million and $8.2 million, respectively.

The entire disclosure for related party transactions. Examples of related party transactions include transactions between (a) a parent company and its subsidiary; (b) subsidiaries of a common parent; (c) and entity and its principal owners; and (d) affiliates.

Property Plant And Equipment [Abstract]

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-Section 08

-Paragraph k

-Article 4

Reference 7: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 850

-SubTopic 10

-Section 50

-Paragraph 6

-URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39691-107864

Reference 8: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 850

-SubTopic 10

-Section 50

-Paragraph 5

-URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39678-107864

Reference 9: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 57

-Paragraph 1-4

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Organization and Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Apr. 30, 2013
Accounting Policies [Abstract]
Organization	*Organization* Ambarella, Inc. (the “Company”) was incorporated in the Cayman Islands on January 15, 2004. The Company is a developer of semiconductor processing solutions for video that enable high-definition video capture, sharing and display. The Company combines its processor design capabilities with its expertise in video and image processing, algorithms and software to provide a technology platform that is designed to be easily scalable across multiple applications and enable rapid and efficient product development. The Company’s system-on-a-chip, or SoC, designs fully integrate high-definition video processing, image processing, audio processing and system functions onto a single chip, delivering exceptional video and image quality, differentiated functionality and low power consumption. The Company sells its solutions to leading original design manufacturers, or ODMs, and original equipment manufacturers, or OEMs, globally.
Basis of presentation	*Basis of presentation* The accompanying unaudited condensed consolidated financial statements have been prepared by the Company in accordance with the instructions to Form 10-Q pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”) and, therefore, do not include all information and notes normally provided in audited financial statements. The accounting policies are described in the “Notes to Consolidated Financial Statements” in the Annual Report on Form 10-K for the 2013 fiscal year filed with the SEC on April 4, 2013 (the “Form 10-K”) and updated, as necessary, in this Form 10-Q. The year-end condensed consolidated balance sheet data presented for comparative purposes was derived from audited financial statements, but does not include all disclosures required by generally accepted accounting principles in the United States (“U.S. GAAP”). In the opinion of management, all adjustments (consisting of normal recurring accruals and other adjustments) considered necessary for a fair presentation have been included. The results of operations for any interim period are not necessarily indicative of, nor comparable to, the results of operations for any other interim period or for a full fiscal year. These unaudited condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and related notes contained in the Form 10-K.
Basis of Consolidation	*Basis of Consolidation* The Company’s fiscal year ends on January 31. The condensed consolidated financial statements of the Company and its subsidiaries have been prepared in conformity with U.S. GAAP. All intercompany transactions and balances have been eliminated in consolidation.
Use of Estimates	*Use of Estimates* The preparation of condensed consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, and the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenue and expense during the reported periods. Actual results could differ from those estimates. On an ongoing basis, management evaluates its estimates and assumptions, including those related to (i) the collectability of accounts receivable; (ii) write down for excess and obsolete inventories; (iii) the estimated useful lives of long-lived assets; (iv) impairment of long-lived assets and financial instruments; (v) warranty obligations; (vi) the valuation of equity instruments; (vii) the realization of tax assets and estimates of tax liabilities, including reserves for uncertain tax positions; and (viii) the recognition and disclosure of contingent liabilities. These estimates and assumptions are based on historical experience and on various other factors which the Company believes to be reasonable under the circumstances. The company may engage third-party valuation specialists to assist with estimates related to the valuation of financial instruments and assets associated with various contractual arrangements, and the valuation of preference and ordinary shares. Such estimates often require the selection of appropriate valuation methodologies and significant judgment. Actual results could differ from these estimates under different assumptions or circumstances.
Concentration of Risk	*Concentration of Risk* The Company’s products are manufactured, assembled and tested by third-party contractors located primarily in Asia. The Company does not have long-term agreements with these contractors. A significant disruption in the operations of one or more of these contractors would impact the production of the Company’s products which could have a material adverse effect on its business, financial condition and results of operations. A substantial portion of the Company’s revenue is derived from sales through its logistics provider, Wintech Microelectronics Co., Ltd., or Wintech, which serves as the Company’s non-exclusive sales representative in all of Asia other than Japan, and through one large direct ODM customer, Chicony Electronics Co., Ltd., or Chicony. Termination of the relationships with these two customers could result in a temporary or permanent loss of revenue and obligation to repurchase unsold product. Furthermore, any credit issues from these two customers could impair their abilities to make timely payment to the Company. See Note 11 for additional information regarding concentration with these two customers. Financial instruments that potentially subject the Company to concentrations of credit risk consist primarily of cash and accounts receivable. The Company places its cash primarily in checking and money market accounts with reputable financial institutions. Deposits held with these financial institutions may exceed the amount of insurance provided on such deposits. The Company has not experienced any material losses on deposits of its cash. The Company does not hold or issue financial instruments for trading purposes. The Company performs ongoing credit evaluations of each of its customers and adjusts credit limits based upon payment history and the customer’s credit worthiness. The Company regularly monitors collections and payments from its customers.
Foreign Currency Transactions	*Foreign Currency Transactions* The U.S. dollar is the functional currency for the Company and its subsidiaries. Monetary assets and liabilities denominated in non-U.S. currencies are re-measured to U.S. dollars using current exchange rates in effect at the balance sheet date. Nonmonetary assets and liabilities are re-measured to U.S. dollars using historical exchange rates. Monetary and other accounts are re-measured to U.S. dollars using average exchange rates in effect during each period. Gains or losses from foreign currency remeasurement are included in other expense in the condensed consolidated statements of operations, and, to date, have not been material.
Cash, Cash Equivalents and Short-Term Investments	*Cash, Cash Equivalents and Short-Term Investments* The Company considers all highly liquid investments with maturities of less than three months at the time of purchase to be cash equivalents. Investments with maturities at the time of acquisition greater than three months are classified as short-term investments as these are considered as available-for-sale in current operations. There were no cash equivalents or short-term investments as of April 30, 2013 and January 31, 2013, respectively.
Cost Method Investment	*Cost Method Investment* The Company accounts for its investment in a privately held company under the cost method and reports the investment in other assets in the condensed consolidated balance sheets. The Company monitors the carrying value of the investment and records a reduction in carrying value when a decline in value is deemed to be other than temporary. To date, the Company has not recognized any impairment losses related to this investment.
Trade Accounts Receivable and Allowances for Doubtful Accounts	*Trade Accounts Receivable and Allowances for Doubtful Accounts* Trade accounts receivable are recorded at the invoiced amount and do not include finance charges. The Company performs ongoing credit evaluation of its customers and generally requires no collateral. The Company assesses the need for allowances for doubtful accounts for estimated losses resulting from the inability of its customers to make required payments by considering factors such as historical collection experience, credit quality, aging of the accounts receivable balances and current economic conditions that may affect a customer’s ability to pay. There were no write-offs of accounts receivable for the three months ended April 30, 2013 and 2012, respectively. There was no allowance for doubtful accounts recorded as of April 30, 2013 and January 31, 2013, respectively.
Fair Market Value of Financial Instruments	*Fair Market Value of Financial Instruments* The carrying amounts reflected in the condensed consolidated balance sheets for cash, accounts receivable, accounts payable, accrued liabilities and other current liabilities, approximate fair value due to the short-term nature. The fair value of outstanding warrants to purchase redeemable convertible preference shares converted into warrants to purchase ordinary shares is described in Note 6.
Inventories	*Inventories* The Company records inventories at the lower of cost or market. The cost includes materials and other production costs and is computed using standard cost on a first-in, first-out basis. Inventory reserves are recorded for estimated obsolescence or unmarketable inventories based on forecast of future demand and market conditions. If actual market conditions are less favorable than projected, or if future demand for the Company’s products decrease, additional inventory write-downs may be required. Once inventory is written down, a new accounting basis has been established and, accordingly, any associated reserve is not reversed until the inventory sold or scrapped. The Company has not recognized any material inventory loss to date.
Property and Equipment	*Property and Equipment* Property and equipment are stated at cost and depreciated using the straight-line method over the estimated useful life of three years for computer equipment, computer software, machinery, equipment and furniture and fixtures. Leasehold improvements are amortized over the shorter of the lease term or their estimated useful lives. Repairs and maintenance are charged to expense as incurred.
Intangible Assets	*Intangible Assets* Technology licenses purchased from third parties and that can be used in alternative research and development projects are capitalized as intangible assets. Capitalized costs are amortized over an estimated economic useful life under a straight-line method and recorded as research and development expenses.
Impairment of Long-Lived Assets	*Impairment of Long-Lived Assets* The Company records long-lived assets at cost and evaluates them for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Events or changes in circumstances that may indicate that an asset is impaired include significant decreases in the market value of an asset, significant underperformance relative to expected historical or projected future results of operations, a change in the extent or manner in which an asset is utilized, significant declines in the estimated fair value of the overall Company for a sustained period, shifts in technology, loss of key management or personnel, changes in the Company’s operating model or strategy and competitive forces. When the sum of the expected future undiscounted cash flows expected to be generated by the related asset group is less than its carrying amount, an impairment loss would be recognized. Should impairment exist, the impairment loss would be measured based on the excess of the carrying amount of the asset over the asset’s estimated fair value. There has been no occurrence of events to date that would trigger an impairment analysis. As such, no impairment charge has been recognized as of April 30, 2013.
Revenue Recognition	*Revenue Recognition* The Company generates revenue from the sale of its SoCs to OEMs or ODMs, either directly or through logistics providers. Revenue from sales directly to OEMs and ODMs is recognized upon shipment provided persuasive evidence of an arrangement exists, legal title to the products and risk of ownership have transferred, the fee is fixed or determinable, and collection of the resulting receivable is reasonably assured. The Company provides its logistics providers with the right to return excess levels of inventory and to future price adjustments. Given the inability to reasonably estimate these price changes and returns, revenue and costs related to shipments to logistics providers are deferred until the Company has received notification from its logistics providers that they have sold the Company’s products. Information reported by the Company’s logistics providers includes product resale price, quantity and end customer shipment information as well as remaining inventory on hand. At the time of shipment to a logistics provider, the Company records a trade receivable as there is a legally enforceable right to receive payment, reduces inventory for the value of goods shipped as legal title has passed to the logistics provider and defers the related margin as deferred revenue in the condensed consolidated balance sheets. Any price adjustments are recorded as a reduction to deferred revenue at the time the adjustments are agreed upon. Arrangements with certain OEM customers provide for pricing that is dependent upon the end products into which the Company’s SoCs are used. These arrangements may also entitle the Company to a share of the product margin ultimately realized by the OEM. The minimum guaranteed amount of revenue related to the sale of products subject to these arrangements is recognized when all other elements of revenue recognition are met. Any amounts at the date of shipment invoiced in excess of the minimum guaranteed contract price are deferred until the additional amounts the Company is entitled to are fixed or determinable. Additional amounts earned by the Company resulting from margin sharing arrangements and determination of the end products into which the products are ultimately incorporated are recognized when end customer sales volume is reported to the Company. The Company also sells a limited amount of software under perpetual licenses that include post-contract customer support, or PCS. The Company does not have evidence of fair value for the PCS and, accordingly, license revenue is recognized ratably over the estimated supporting period in accordance with ASC 985, Software Revenue Recognition. The revenue from those licenses comprised 1% and 3% of the Company’s total revenue for the three months ended April 30, 2013 and 2012, respectively.
Cost of Revenue	*Cost of Revenue* Cost of revenue includes cost of materials, cost associated with packaging and assembly, testing and shipping, cost of personnel, stock-based compensation, logistics and quality assurance, warranty cost, royalty expense, write-downs of inventories and allocation of overhead.
Warranty Costs	*Warranty Costs* The Company typically provides warranty on its products. The Company accrues for the estimated warranty costs at the time when revenue is recognized. The warranty accruals are regularly monitored by management based upon historical experience and any specifically identified failures. While the Company engages in extensive product quality assessment, actual product failure rates, material usage or service delivery costs could differ from estimates and revisions to the estimated warranty liability would be required. The Company’s warranty accruals have not been material to date.
Research and Development	*Research and Development* Research and development costs are expensed as incurred and consist primarily of personnel costs, product development costs, which include engineering services, development software and hardware tools, license fees, cost of fabrication of masks for prototype products, other development materials costs, depreciation of equipment used in research and development and allocation of facilities costs.
Selling, General and Administrative	*Selling, General and Administrative* Selling, general and administrative expense consists of personnel costs, travel and trade show costs, legal expenses, other professional services and occupancy costs. Advertising expenses have not been material to date.
Operating Leases	*Operating Leases* The Company recognizes rent expense on a straight-line basis over the term of the lease. The difference between rent expense and rent paid is recorded as deferred rent and is included in accrued liabilities in the condensed consolidated balance sheets.
Income Taxes	*Income Taxes* The Company records income taxes using the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been recognized in its financial statements or tax returns. In estimating future tax consequences, generally all expected future events other than enactments or changes in the tax law or rates are considered. Valuation allowances are provided when necessary to reduce deferred tax assets to the amount expected to be realized. The Company applies authoritative guidance for the accounting for uncertainty in income taxes. The guidance requires that tax effects of a position be recognized only if it is “more likely than not” to be sustained based solely on its technical merits as of the reporting date. Upon estimating the Company’s tax positions and tax benefits, the Company considered and evaluated numerous factors, which may require periodic adjustments and which may not reflect the final tax liabilities. The Company adjusts its financial statements to reflect only those tax positions that are more likely than not to be sustained under examination. As part of the process of preparing condensed consolidated financial statements, the Company is required to estimate its taxes in each of the jurisdictions in which it operates. The Company estimates actual current tax exposure together with assessing temporary differences resulting from differing treatment of items, such as accruals and allowances not currently deductible for tax purposes. These differences result in deferred tax assets, which are included in the condensed consolidated balance sheets. In general, deferred tax assets represent future tax benefits to be received when certain expenses previously recognized in the condensed consolidated statements of operations become deductible expenses under applicable income tax laws, or loss or credit carryforwards are utilized. In assessing whether deferred tax assets may be realized, management considers whether it is more likely than not that some portion or all of deferred tax assets will be realized. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income. The Company makes estimates and judgments about its future taxable income based on assumptions that are consistent with its plans and estimates. Should the actual amounts differ from estimates, the amount of valuation allowance could be materially impacted. Any adjustment to the deferred tax asset valuation allowance would be recorded in the income statement for the periods in which the adjustment is determined to be required.
Stock-Based Compensation	*Stock-Based Compensation* The Company measures stock-based compensation for equity awards granted to employees and directors based on the estimated fair value on the grant date, and recognizes that compensation as expense using the straight-line attribution method for service condition awards or using the graded-vesting attribution method for awards with performance conditions over the requisite service period, which is typically the vesting period of each award. The Company estimates the fair value of awards of restricted stock units, or RSUs, based on the fair market value of its ordinary shares on the date of grant. The Company uses the Black-Scholes option pricing model to determine the fair value of stock option grants and shares issuance pursuant to its employee stock purchase plan, or ESPP. Determining the fair value of stock option awards on the grant date or the fair value of ESPP shares on the offering date requires the input of various assumptions, including stock price of the underlying ordinary share, the exercise price of the stock option or the offering price of the ESPP share, expected volatility, expected term, risk-free interest rate and dividend rate. The expected term for stock option is calculated using the simplified method as prescribed by the guidance provided by the Securities and Exchange Commission, as neither relevant historical experience nor other relevant data are available to estimate future exercise behavior. The expected term for shares issuance pursuant to the ESPP is the offering period. The expected volatility is based on the historical volatilities of similar companies whose share prices are publicly available for a period commensurate with the expected term. The risk-free interest rate is derived from the average U.S. Treasury constant maturity rates during the respective periods commensurate with the expected term. The expected dividend yield is zero because the Company has not historically paid dividends and has no present intention to pay dividends. The Company uses historical data to estimate pre-vesting award forfeitures and records stock-based compensation only for those awards that are expected to vest. Forfeitures are estimated at the time of grant and revised if necessary in subsequent periods if actual forfeitures differ from estimates. The Company recognizes non-employee stock-based compensation expense based on the estimated fair value of the equity instrument determined by the Black-Scholes option pricing model. The fair value of the non-employee awards is remeasured at each reporting period until services required under the arrangement are completed, which is the vesting date. Prior to the initial public offering, or IPO, the Company engaged an independent appraiser to assist in the valuation of its ordinary share price. The board of directors directed these regular valuations and had input into determining the relevant objective and subjective factors accounted for and relevant approaches in each valuation. After the IPO, the exercise price of stock option awards is determined based on the closing price of the Company’s ordinary shares traded on NASDAQ on the grant date.
Net Income Per Ordinary Share	*Net Income Per Ordinary Share* The Company applies the two-class method to calculate and present net income per ordinary share. Under the two-class method, net income is allocated between ordinary shares and other participating securities based on their participating rights. Participating securities are defined as securities that may participate in undistributed earnings with ordinary shares, whether that participation is conditioned upon the occurrence of a specified event or not. Basic net income per ordinary share is computed by dividing net income allocable to ordinary shares by the weighted-average number of ordinary shares outstanding for the period. Diluted net income per ordinary share is computed by dividing net income allocable to ordinary shares and income allocable to participating securities, to the extent they are dilutive, by the weighted-average number of ordinary shares outstanding, including the dilutive effects of participating securities on an if-converted basis plus the dilutive effects of ordinary shares. The Company’s potential dilutive ordinary share equivalents consist of incremental ordinary shares issuable upon the exercise of options, upon the issuance of shares pursuant to the ESPP, upon the release of vested restricted stock units, upon the conversion of its redeemable convertible preference shares and upon the exercise of warrants. The Company performs an assessment as to whether instruments granted in stock-based payment transactions are participating securities. Stock-based payment awards that have not yet vested meet the definition of a participating security provided the right to receive the dividend is non-forfeitable and non-contingent. These participating securities should be included in the computation of basic net income per share under the two-class method. The Company has concluded that its non-vested early-exercised options meet the definition of a participating security and should be included in the Company’s computation of basic earnings per ordinary share.
Comprehensive Income	*Comprehensive Income* There are no differences between comprehensive income as defined by ASC 220, Comprehensive Income, and net income as reported in the Company’s condensed consolidated statements of operations.
Recent Accounting Pronouncements	*Recent Accounting Pronouncements* In February 2013, the FASB issued ASU No. 2013-02, Reporting of Amounts Reclassified Out of Accumulated Other Comprehensive Income (“AOCI”). This new guidance requires that the Company present either in a single note or parenthetically on the face of the financial statements, the effect of significant amounts reclassified from each component of accumulated other comprehensive income based on its source and the income statement line items affected by the reclassification. If a component is not required to be reclassified to net income in its entirety, the Company would instead cross reference to the related footnote for additional information. This guidance only impacts disclosures within the Company’s consolidated financial statements and notes to the consolidated financial statements and does not result in a change to the accounting treatment of AOCI. This new guidance became effective prospectively for fiscal years, and interim periods with those years, beginning after December 15, 2012. The Company adopted this guidance and the adoption did not have an impact on its financial position, results of operations or disclosures.

Inventories (Tables)

3 Months Ended

Apr. 30, 2013

Inventory Disclosure [Abstract]

Schedule of Inventory

Inventory at April 30, 2013 and January 31, 2013 consisted of the following:


	As of April 30, 2013		As of January 31, 2013
	(in thousands)

Work-in-progress	$	4,845	$	4,044
Finished goods		4,480		4,874


Total	$	9,325	$	8,918

Property and Equipment, Net (Tables)

3 Months Ended

Apr. 30, 2013

Schedule of Property and Equipment

Property and equipment at April 30, 2013 and January 31, 2013 consisted of the following:


	As of April 30, 2013			As of January 31, 2013
	(in thousands)

Computer equipment and software	$	2,867		$	2,810
Machinery and equipment		2,063			2,050
Furniture and fixtures		397			397
Leasehold improvements		642			642
Construction in progress		1,370			827

		7,339			6,726

Less: accumulated depreciation and amortization		(4,363	)		(4,190	)


Total property and equipment, net	$	2,976		$	2,536

Tabular disclosure of the useful life and salvage value of long-lived, physical assets that are used in the normal conduct of business to produce goods and services and not intended for resale. Examples include land, buildings, machinery and equipment, and other types of furniture and equipment including, but not limited to, office equipment, furniture and fixtures, and computer equipment and software.

+ References+ Details

Accrued Liabilities (Tables)

3 Months Ended

Apr. 30, 2013

Schedule of Accrued Liabilities

Accrued liabilities at April 30, 2013 and January 31, 2013 consisted of the following:


	As of April 30, 2013		As of January 31, 2013
	(in thousands)

Accrued employee compensation	$	5,259	$	8,599
Refundable exercised unvested options		161		210
Accrued warranty		335		352
Accrued rebates		192		272
Accrued product development costs		3,920		2,875
Other accrued liabilities		1,317		2,111


Total accrued liabilities	$	11,184	$	14,419

Deferred Revenue and Deferred Cost (Tables)

3 Months Ended

Apr. 30, 2013

Revenue Recognition [Abstract]

Schedule of Deferred Revenue and Related Cost

Deferred revenue and related cost at April 30, 2013 and January 31, 2013 consisted of the following:


	As of April 30, 2013			As of January 31, 2013
	(in thousands)

Deferred revenue on product shipments	$	5,051		$	3,827
Deferred revenue from licenses		300			485
Deferred cost of revenue on product shipments		(1,327	)		(861	)


Total deferred income	$	4,024		$	3,451

Capital Stock (Tables)

3 Months Ended

Apr. 30, 2013

Schedule of Ordinary Shares Reserved for Future Issuance

As of April 30, 2013 and January 31, 2013, the following ordinary shares were reserved for future issuance:


	As of April 30, 2013		As of January 31, 2013

Shares reserved for options and restricted stock units		6,836,469		5,818,126
Shares reserved for employee stock purchase plan		798,383		460,445
Shares reserved for warrants		11,167		36,292

Employee Benefits and Stock-based Compensation (Tables)

3 Months Ended

Apr. 30, 2013

Compensation And Retirement Disclosure [Abstract]

Classification of Stock-Based Compensation

The following table presents the classification of stock-based compensation for the periods indicated:


	Three Months Ended April 30,
	2013		2012
	(in thousands)
Stock-based compensation:
Cost of revenue	$	34	$	14
Research and development		974		532
Selling, general and administrative		598		397


Total stock-based compensation	$	1,606	$	943

Weighted-Average Assumptions Used to Estimate Fair Value

The following table sets forth the weighted-average assumptions used to estimate the fair value of the stock options for the periods indicated:


	Three Months Ended April 30,
	2013			2012
Stock Options:
Volatility		65	%		66	%
Risk-free interest rate		1.17	%		1.10	%
Expected term (years)		6.05			6.05
Dividend yield		0	%		0	%

Stock Option Activities

The following table summarizes stock option activities for the three months ended April 30, 2013:


	Option Outstanding
	Shares			Weighted- Average Exercise Price		Weighted- Average Grant-date Fair Value		Total Intrinsic Value of options Exercised (in thousands)		Weighted- Average Remaining Contractual Term (in years)		Aggregate Intrinsic Value (in thousands)

Outstanding at January 31, 2013		4,344,535			6.07
Granted		60,000			13.74	$	8.15
Exercised		(158,871	)		3.11			$	1,689
Forfeited		(31,561	)		8.45


Outstanding at April 30, 2013		4,214,103			6.27						6.67	$	31,311

Exercisable at April 30, 2013		3,084,125			5.42						6.07	$	25,522

Vested and expected to vest at April 30, 2013		4,140,490			6.23						6.64	$	30,940

Restricted Stock Units Activities

The following table summarizes restricted stock units activities for the three months ended April 30, 2013:


	Shares			Weighted- Average Grant-Date Fair Value
Unvested at January 31, 2013		339,217		$	9.99
Granted		11,000			13.74
Released		(39,364	)		9.99
Forfeited		(5,464	)		9.99


Unvested at April 30, 2013		305,389		$	10.13

Computation of Basic and Diluted Net Income Per Ordinary Share

Tabular disclosure of the allocation of equity-based compensation costs to a given line item on the balance sheet and income statement for the period. This may include the reporting line for the costs and the amount capitalized and expensed.

+ References+ Details

Net Income Per Ordinary Share (Tables)

3 Months Ended

Apr. 30, 2013

Earnings Per Share [Abstract]

The following table sets forth the computation of basic and diluted net income per ordinary share for the periods indicated:


	Three Months Ended April 30,
	2013			2012
	(in thousands, except share and per share data)
Numerator:
Net income	$	4,741		$	2,602
Less: amount allocable to preference shareholders		—			(2,028	)
Less: amount allocable to unvested early exercised options		(9	)		(8	)


Net income allocable to ordinary shareholders - basic	$	4,732		$	566


Undistributed earnings reallocated to ordinary shareholders		1			68


Net income allocable to ordinary shareholders - diluted	$	4,733		$	634


Denominator:
Weighted-average ordinary shares outstanding		27,103,129			7,622,621
Less: weighted-average unvested early exercised options subject to repurchase		(46,197	)		(103,261	)


Weighted-average ordinary shares - basic		27,056,932			7,519,360


Effect of potentially dilutive securities:
Employee stock options		1,688,768			1,512,350
Restricted stock units		141,647			—
Employee stock purchase plan		170,817			—
Warrants to purchase ordinary shares		7,898			—

Weighted-average ordinary shares - diluted		29,066,062			9,031,710


Net income per ordinary share:
Basic	$	0.17		$	0.08


Diluted	$	0.16		$	0.07

Weighted-Average Potentially Dilutive Securities Excluded from Computation of Diluted Net Income Per Ordinary Share

The following weighted-average potentially dilutive securities were excluded from the computation of diluted net income per ordinary share as their effect would have been antidilutive:


	Three Months Ended April 30,
	2013		2012

Options to purchase ordinary shares		390,928		2,046,941
Restricted stock units		6,303		—
Employee stock purchase plan		—		—
Early exercised options subject to repurchase		46,197		103,261
Redeemable convertible preference shares (if-converted basis)		—		13,315,727
Warrants to purchase redeemable convertible preference shares (if-converted basis)		—		36,292
Warrants to purchase ordinary shares		—		—


		443,428		15,502,221

Income Taxes (Tables)

3 Months Ended

Apr. 30, 2013

Income Tax Disclosure [Abstract]

Summary of Reported Income Tax

The Company reported the following income tax for the periods indicated:


	Three Months Ended April 30,
	2013		2012
	(in thousands)

Income tax expense	$	473	$	303

Commitments and Contingencies (Tables)

3 Months Ended

Apr. 30, 2013

Commitments And Contingencies Disclosure [Abstract]

Future Annual Minimum Lease Payments

Future annual minimum lease payments under these operating leases with initial lease terms in excess of one year are as follows:


	As of April 30, 2013
Fiscal Year	(in thousands)
2014	$	2,718
2015		1,498
2016		1,346
2017		933
2018		955


	$	7,450

Segment Reporting (Tables)

3 Months Ended

Apr. 30, 2013

Segment Reporting [Abstract]

Company's Revenue by Geographic Region

The following table sets forth the Company’s revenue by geographic region for the periods indicated:


	Three Months Ended April 30,
	2013		2012
	(in thousands)

Hong Kong	$	28,774	$	21,200
Asia Pacific		256		177
United States		2,605		3,036
North America		962		320
Europe		1,344		1,188


Total revenue	$	33,941	$	25,921

Tabular disclosure of the names of foreign countries from which revenue is material and the amount of revenue from external customers attributed to those countries. An entity may also provide subtotals of geographic information about groups of countries.

+ References+ Details

Organization and Summary of Significant Accounting Policies - Additional Information (Detail)	3 Months Ended
	Apr. 30, 2013	Apr. 30, 2012
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Estimated useful life	3 years	3 years
Percentage of license revenue to company's revenue	1.00%	3.00%
Expected dividend yield	0.00%	0.00%

Inventories - Schedule of Inventory (Detail) (USD $) In Thousands, unless otherwise specified	Apr. 30, 2013	Jan. 31, 2013
Inventory Disclosure [Abstract]
Work-in-progress	$ 4,845	$ 4,044
Finished goods	4,480	4,874
Total	$ 9,325	$ 8,918

Carrying amount, net of reserves and adjustments, as of the balance sheet date of merchandise or goods which are partially completed. This inventory is generally comprised of raw materials, labor and factory overhead costs, which require further materials, labor and overhead to be converted into finished goods, and which generally require the use of estimates to determine percentage complete and pricing.

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Property and Equipment, Net - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Apr. 30, 2013	Apr. 30, 2012
Property Plant And Equipment [Abstract]
Depreciation	$ 194	$ 176

The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation.

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Property and Equipment, Net - Schedule of Property and Equipment (Detail) (USD $) In Thousands, unless otherwise specified	Apr. 30, 2013	Jan. 31, 2013
Property Plant And Equipment [Abstract]
Computer equipment and software	$ 2,867	$ 2,810
Machinery and equipment	2,063	2,050
Furniture and fixtures	397	397
Leasehold improvements	642	642
Construction in progress	1,370	827
Property and equipment, gross	7,339	6,726
Less: accumulated depreciation and amortization	(4,363)	(4,190)
Total property and equipment, net	$ 2,976	$ 2,536

The cumulative amount of depreciation, depletion and amortization (related to property, plant and equipment, but not including land) that has been recognized in the income statement.

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Gross amount of long-lived physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

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Amount, net of accumulated depreciation, depletion and amortization, of long-lived physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

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Accrued Liabilities - Schedule of Accrued Liabilities (Detail) (USD $) In Thousands, unless otherwise specified	Apr. 30, 2013	Jan. 31, 2013
Payables And Accruals [Abstract]
Accrued employee compensation	$ 5,259	$ 8,599
Refundable exercised unvested options	161	210
Accrued warranty	335	352
Accrued rebates	192	272
Accrued product development costs	3,920	2,875
Other accrued liabilities	1,317	2,111
Total accrued liabilities	$ 11,184	$ 14,419

Carrying value as of the balance sheet date of obligations incurred through that date and payable arising from transactions not otherwise specified in the taxonomy. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

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Carrying value as of the balance sheet date of obligations incurred through that date and payable for estimated claims under standard and extended warranty protection rights granted to customers. For classified balance sheets, represents the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

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Deferred Revenue and Deferred Cost - Schedule of Deferred Revenue and Related Cost (Detail) (USD $) In Thousands, unless otherwise specified	Apr. 30, 2013	Jan. 31, 2013
Deferred Revenue Disclosure [Abstract]
Deferred revenue on product shipments	$ 5,051	$ 3,827
Deferred revenue from licenses	300	485
Deferred cost of revenue on product shipments	(1,327)	(861)
Total deferred income	$ 4,024	$ 3,451

Capital Stock - Additional Information (Detail) (USD $)	3 Months Ended
Capital Stock - Additional Information (Detail) (USD $)	Apr. 30, 2013	Jan. 31, 2013
Equity [Abstract]
Preference shares, shares authorized	20,000,000	20,000,000
Preference shares, par value	$ 0.00045	$ 0.00045
Preference shares, shares issued	0	0
Preference shares, shares outstanding	0	0
Company issued warrants to purchase Series B redeemable convertible preference shares, exercise price	3.582	3.582
Company issued warrants to purchase Series B redeemable convertible preference shares		36,292
Total ordinary share warrants exercised	25,125
Total ordinary share warrants outstanding	11,167	36,292
Total ordinary shares authorized	200,000,000	200,000,000

Capital Stock - Schedule of Ordinary Shares Reserved for Future Issuance (Detail)	Apr. 30, 2013	Jan. 31, 2013
Equity [Abstract]
Shares reserved for options and restricted stock units	6,836,469	5,818,126
Shares reserved for employee stock purchase plan	798,383	460,445
Shares reserved for warrants	11,167	36,292

Employee Benefits and Stock-based Compensation - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		12 Months Ended
	Apr. 30, 2013	Apr. 30, 2012	Jan. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Voting power of all classes of company's shares	10.00%	10.00%	10.00%
Term of up to 10 years from grant date	10 years	10 years	10 years
Vesting period of RSUs before IPO	1/16th of the RSUs shall vest each 3 months following the vesting commencement date, 100% vest on the fourth anniversary date		1/16th of the RSUs shall vest each 3 months following the vesting commencement date, 100% vest on the fourth anniversary date
Percentage of salary contribution by employees	10.00%		10.00%
Percentage of purchase price of ordinary shares	85.00%		85.00%
Unvested early exercised options, repurchased	86,005		84,377
Unvested shares subject to the Company's repurchase rights	39,242		53,151
Closing price of ordinary shares	$ 13.70
Employee stock option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of stock option for new hire	Vest 25% on the first anniversary date of the grant and the remainder ratably over the following 36 months	Vest 25% on the first anniversary date of the grant and the remainder ratably over the following 36 months	Vest 25% on the first anniversary date of the grant and the remainder ratably over the following 36 months
Total unrecognized compensation cost	$ 6.7		$ 7.3
Weighted-average period	2 years 1 month 24 days		2 years 3 months 4 days
Restricted stock units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of RSUs before IPO	1/16th of the RSUs shall vest each 3 months following the vesting commencement date, 100% vest on the fourth anniversary date		1/16th of the RSUs shall vest each 3 months following the vesting commencement date, 100% vest on the fourth anniversary date
Vesting period of RSUs for new hire	Vest 25% on the first anniversary of the vesting commencement date and 1/16th of the RSUs vest each 3 months thereafter		Vest 25% on the first anniversary of the vesting commencement date and 1/16th of the RSUs vest each 3 months thereafter
Total unrecognized compensation cost of other than options	2.0		2.4
Weighted-average period	1 year 9 months 29 days		1 year 9 months 7 days
Aggregate intrinsic value of unvested restricted stock units	$ 4.2
Incentive Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price of stock options as percentage of fair market value at grant date	110.00%	110.00%	110.00%
Non Statutory Stock Option Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price of stock options as percentage of fair market value at grant date	100.00%	100.00%	100.00%

Employee Benefits and Stock-Based Compensation - Classification of Stock-Based Compensation (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Apr. 30, 2013	Apr. 30, 2012
Stock-based compensation:
Total stock-based compensation	$ 1,606	$ 943
Cost of revenue [Member]
Stock-based compensation:
Total stock-based compensation	34	14
Research and development [Member]
Stock-based compensation:
Total stock-based compensation	974	532
Selling, general and administrative [Member]
Stock-based compensation:
Total stock-based compensation	$ 598	$ 397

Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

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Employee Benefits and Stock-Based Compensation - Weighted-Average Assumptions Used to Estimate Fair Value (Detail)	3 Months Ended
	Apr. 30, 2013	Apr. 30, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividend yield	0.00%	0.00%
Options to purchase ordinary shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Volatility	65.00%	66.00%
Risk-free interest rate	1.17%	1.10%
Expected term (years)	6 years 18 days	6 years 18 days
Dividend yield	0.00%	0.00%

The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

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Employee Benefits and Stock-Based Compensation - Stock Option Activities (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Apr. 30, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Shares, Outstanding	4,344,535
Shares, Granted	60,000
Shares, Exercised	(158,871)
Shares, Forfeited	(31,561)
Shares, Outstanding	4,214,103
Shares, Exercisable	3,084,125
Shares, Vested and expected to vest	4,140,490
Weighted-Average Exercise Price, Outstanding	$ 6.07
Weighted-Average Exercise Price, Granted	$ 13.74
Weighted-Average Exercise Price, Exercised	$ 3.11
Weighted-Average Exercise Price, Forfeited	$ 8.45
Weighted-Average Exercise Price, Outstanding	$ 6.27
Weighted-Average Exercise Price, Exercisable	$ 5.42
Weighted-Average Exercise Price, Vested and expected to vest	$ 6.23
Weighted-Average Grant-date Fair Value, Granted	$ 8.15
Total Intrinsic Value of options Exercised, Exercised	$ 1,689
Weighted-Average Remaining Contractual Term, Outstanding	6 years 8 months 1 day
Weighted-Average Remaining Contractual Term, Exercisable	6 years 26 days
Weighted-Average Remaining Contractual Term, Vested and expected to vest	6 years 7 months 21 days
Aggregate Intrinsic Value, Outstanding	31,311
Aggregate Intrinsic Value, Exercisable	25,522
Aggregate Intrinsic Value, Vested and expected to vest	$ 30,940

Employee Benefits and Stock-Based Compensation - Restricted Stock Units Activities (Detail) (USD $)	3 Months Ended
	Apr. 30, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Shares, Unvested, beginning balance	339,217
Shares, Granted	11,000
Shares, Released	(39,364)
Shares, Forfeited	(5,464)
Shares, Unvested, ending balance	305,389
Weighted-Average Grant-Date Fair Value, Unvested beginning balance	$ 9.99
Weighted-Average Grant-Date Fair Value, Granted	$ 13.74
Weighted-Average Grant-Date Fair Value, Released	$ 9.99
Weighted-Average Grant-Date Fair Value, Forfeited	$ 9.99
Weighted-Average Grant-Date Fair Value, Unvested ending balance	$ 10.13

The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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The weighted average fair value of nonvested awards on equity-based plans excluding option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, revenue or profit achievement stock award plan) for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain title to proceeds from the sale of the award or underlying shares or units.

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The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

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Net Income Per Ordinary Share - Computation of Basic and Diluted Net Income Per Ordinary Share (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Apr. 30, 2013	Apr. 30, 2012
Numerator:
Net income	$ 4,741	$ 2,602
Less: amount allocable to preference shareholders		(2,028)
Less: amount allocable to unvested early exercised options	(9)	(8)
Net income allocable to ordinary shareholders - basic	4,732	566
Undistributed earnings reallocated to ordinary shareholders	1	68
Net income allocable to ordinary shareholders - diluted	$ 4,733	$ 634
Denominator:
Weighted-average ordinary shares outstanding	27,103,129	7,622,621
Less: weighted-average unvested early exercised options subject to repurchase	(46,197)	(103,261)
Weighted-average ordinary shares - basic	27,056,932	7,519,360
Effect of potentially dilutive securities:
Employee stock options	1,688,768	1,512,350
Restricted stock units	141,647
Employee stock purchase plan	170,817
Warrants to purchase ordinary shares	7,898
Weighted-average ordinary shares - diluted	29,066,062	9,031,710
Net income per ordinary share:
Basic	$ 0.17	$ 0.08
Diluted	$ 0.16	$ 0.07

Net Income Per Ordinary Share - Weighted-Average Potentially Dilutive Securities Excluded from Computation of Diluted Net Income Per Ordinary Share (Detail)	3 Months Ended
	Apr. 30, 2013	Apr. 30, 2012
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from computation of Earnings Per Share	443,428	15,502,221
Options to purchase ordinary shares [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from computation of Earnings Per Share	390,928	2,046,941
Restricted stock units [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from computation of Earnings Per Share	6,303
Employee stock purchase plan [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from computation of Earnings Per Share
Early exercised options subject to repurchase [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from computation of Earnings Per Share	46,197	103,261
Redeemable convertible preference shares (if-converted basis) [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from computation of Earnings Per Share		13,315,727
Warrants to purchase redeemable convertible preference shares (if-converted basis) [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from computation of Earnings Per Share		36,292
Warrants to purchase ordinary shares [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from computation of Earnings Per Share

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Antidilution

-URI http://asc.fasb.org/extlink&oid=6505113

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Diluted Earnings Per Share

-URI http://asc.fasb.org/extlink&oid=6510752

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Contingent Stock Agreement

-URI http://asc.fasb.org/extlink&oid=6508534

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 260

-SubTopic 10

-Section 50

-Paragraph 1

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 128

-Paragraph 40

-Subparagraph c

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 128

-Paragraph 13, 14

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Emerging Issues Task Force (EITF)

-Number 07-4

-Paragraph 4

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 8: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 128

-Paragraph 171

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Income Taxes - Summary of Reported Income Tax (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Apr. 30, 2013	Apr. 30, 2012
Income Tax Disclosure [Abstract]
Income tax expense	$ 473	$ 303

The sum of the current income tax expense or benefit and the deferred income tax expense or benefit pertaining to continuing operations.

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Income Taxes - Additional Information (Detail) (USD $)	3 Months Ended
Income Taxes - Additional Information (Detail) (USD $)	Apr. 30, 2013	Apr. 30, 2012
Income Tax Disclosure [Abstract]
Income tax expense	$ 473,000	$ 303,000
Estimated effective tax rate	9.10%	10.40%
Unrecognized tax benefits	$ 3,000,000

A ratio calculated by dividing the reported amount of income tax expense attributable to continuing operations for the period by GAAP-basis pretax income from continuing operations.

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The sum of the current income tax expense or benefit and the deferred income tax expense or benefit pertaining to continuing operations.

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Commitments and Contingencies - Additional Information (Detail) (USD $)	1 Months Ended	3 Months Ended			3 Months Ended		12 Months Ended
	Mar. 31, 2013 sqft	Apr. 30, 2013	Apr. 30, 2012	Jan. 31, 2013	Apr. 30, 2013 2017 [Member]	Apr. 30, 2013 Indemnification Agreement [Member]	Jan. 31, 2013 Indemnification Agreement [Member]
Commitments And Contingencies [Line Items]
Net rental expenses		$ 1,100,000	$ 1,100,000
Lease agreement rental area in square feet	35,000
Initial lease term	5 years
Lease termination year	2018-04
Monthly basic rent obligation		44,550			65,400
Average monthly basic rent expense		59,800
Total manufacturing purchase commitments		13,100,000		15,100,000
Payments under indemnification obligations						0	0
Liabilities recorded under indemnification obligations						$ 0	$ 0

Commitments and Contingencies - Future Annual Minimum Lease Payments (Detail) (USD $) In Thousands, unless otherwise specified	Apr. 30, 2013
Commitments And Contingencies Disclosure [Abstract]
2014	$ 2,718
2015	1,498
2016	1,346
2017	933
2018	955
Total future annual minimum lease payments	$ 7,450

Amount of required minimum rental payments for leases having an initial or remaining non-cancelable letter-terms in excess of one year.

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Amount of required minimum rental payments maturing in the next fiscal year following the latest fiscal year for operating leases having an initial or remaining non-cancelable letter-terms in excess of one year.

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Amount of required minimum rental payments maturing in the fifth fiscal year following the latest fiscal year for operating leases having an initial or remaining non-cancelable letter-terms in excess of one year.

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Amount of required minimum rental payments maturing in the forth fiscal year following the latest fiscal year for operating leases having an initial or remaining non-cancelable letter-terms in excess of one year.

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Amount of required minimum rental payments maturing in the third fiscal year following the latest fiscal year for operating leases having an initial or remaining non-cancelable letter-terms in excess of one year.

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Amount of required minimum rental payments maturing in the second fiscal year following the latest fiscal year for operating leases having an initial or remaining non-cancelable letter-terms in excess of one year.

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Segment Reporting - Company's Revenue by Geographic Region (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Apr. 30, 2013	Apr. 30, 2012
Revenue from External Customer [Line Items]
Total revenue	$ 33,941	$ 25,921
Hong Kong [Member]
Revenue from External Customer [Line Items]
Total revenue	28,774	21,200
Asia Pacific [Member]
Revenue from External Customer [Line Items]
Total revenue	256	177
United States [Member]
Revenue from External Customer [Line Items]
Total revenue	2,605	3,036
North America [Member]
Revenue from External Customer [Line Items]
Total revenue	962	320
Europe [Member]
Revenue from External Customer [Line Items]
Total revenue	$ 1,344	$ 1,188

Segment Reporting - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		12 Months Ended
	Apr. 30, 2013	Apr. 30, 2012	Jan. 31, 2013
Entity Wide Portfolio Carrying Amount, Major Customer [Line Items]
Percentage of revenue	82.00%
Accounts receivable from major customers	$ 21.7		$ 17.6
Customer A [Member]
Entity Wide Portfolio Carrying Amount, Major Customer [Line Items]
Threshold limit	10.00%	10.00%	10.00%
Percentage of revenue		75.00%
Customer B [Member]
Entity Wide Portfolio Carrying Amount, Major Customer [Line Items]
Threshold limit	10.00%		10.00%

Related-Party Transactions - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		12 Months Ended
	Apr. 30, 2013	Apr. 30, 2012	Jan. 31, 2013
Related Party Transaction [Line Items]
Percentage of entity's voting stock owned by related party	10.00%	10.00%	10.00%
Affiliated Entity [Member]
Related Party Transaction [Line Items]
Total commitment payment of license	$ 10.2
Payment for license fees	0.4	0.5
Operating lease expense related to license agreements included in research and development cost	0.4	0.4
Shareholder [Member]
Related Party Transaction [Line Items]
Percentage of investor own voting stock			4.60%
Recognized revenue from related party	13.4	19.4
Account receivables from related party	$ 7.6		$ 8.2

The aggregate amount of receivables to be collected from related parties where one party can exercise control or significant influence over another party; including affiliates, owners or officers and their immediate families, pension trusts, and so forth, at the financial statement date. which are usually due within one year (or one business cycle).

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