Stock-based Compensation (Tables)

3 Months Ended

Apr. 30, 2021

Disclosure Of Compensation Related Costs Sharebased Payments [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,
	2021		2020
	(in thousands)
Stock-based compensation:
Cost of revenue	$	323	$	297
Research and development		11,194		9,896
Selling, general and administrative		7,325		5,843
Total stock-based compensation	$	18,842	$	16,036

Weighted-Average Assumptions Used to Estimate Fair Value

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

	Three Months Ended April 30,
	2021			2020
Stock Options:
Volatility		51	%		50	%
Risk-free interest rate		0.99	%		0.74	%
Expected term (years)	5.3			5.89
Dividend yield		0	%		0	%
Employee stock purchase plan awards:
Volatility		61	%		61	%
Risk-free interest rate		0.06	%		0.29	%
Expected term (years)	0.5			0.5
Dividend yield		0	%		0	%

Stock Option Activities

The following table summarizes stock option activities for the period indicated:

	Option Outstanding
										Weighted-
								Total Intrinsic		Average
						Weighted-		Value Of		Remaining		Aggregate
				Weighted-		Average		Options		Contractual		Intrinsic
				Average		Grant-date		Exercised		Term		Value
	Shares			Exercise Price		Fair Value		(in thousands)		(in years)		(in thousands)
Outstanding at January 31, 2021		719,143		$	38.33
Granted		13,100			111.51	$	51.10
Exercised		(77,403	)		27.77			$	6,363
Forfeited		(3,131	)		55.43
Expired		—			—
Outstanding at April 30, 2021		651,709			40.98					4.46		$	37,040
Exercisable at April 30, 2021		531,761		$	36.80						3.56	$	32,298

Restricted Stock Units Activities

The following table summarizes the restricted stock units activities for the period indicated:

				Weighted-
				Average
				Grant-Date
	Shares			Fair Value
Unvested at January 31, 2021		2,871,801		$	51.73
Granted		325,866			107.62
Vested		(565,717	)		51.63
Forfeited		(11,974	)		60.25
Unvested at April 30, 2021		2,619,976		$	58.67