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