Note 11 - Equity Incentive Plan (Tables)

3 Months Ended

Mar. 31, 2022

Notes Tables

Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Table Text Block]

	Three Months Ended March 31,
	2022		2021
Cost of revenue	$	176	$	129
Research and development		367		241
Selling, general and administrative		2,002		1,889
Total stock-based compensation expense	$	2,545	$	2,259

Share-Based Payment Arrangement, Option, Activity [Table Text Block]

	Number of Options			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (in years)		Aggregate Intrinsic Value (in thousands)
Outstanding as of December 31, 2021		1,175,993		$	39.56
Granted		416,197		$	28.37
Exercised		(437	)	$	9.10			$	10
Forfeited and canceled		(47,858	)	$	38.23
Outstanding as of March 31, 2022		1,543,895		$	36.59		8.6	$	9
Vested, March 31, 2022		485,869		$	41.89		7.5	$	9
Vested or expected to vest, March 31, 2022		1,543,895		$	36.59		8.6	$	9

Schedule of Share-Based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]

	Three Months Ended March 31,
	2022								2021
Risk free interest rate		1.3	%		-		1.9	%		0.3	%		-		0.6	%
Expected volatility		53.8	%		-		54.6	%		54.8	%		-		55.4	%
Expected life (years)					4.5								4.0
Expected dividend yield					0.0	%							0.0	%
Fair value per option				$	11.37							$	13.90

	2022
Risk-free interest rate		0.06	%
Expected stock price volatility		32.58	%
Expected life of options (in years)		0.5
Expected dividend yield		0.0	%

Share-Based Payment Arrangement, Restricted Stock and Restricted Stock Unit, Activity [Table Text Block]

	Number of Shares			Weighted Average Fair Value
Outstanding as of December 31, 2021		412,658		$	36.33
Granted		420,452		$	25.75
Vested		(87,953	)	$	35.19
Forfeited and cancelled		(32,376	)	$	35.27
Outstanding as of March 31, 2022		712,781		$	30.28

Schedule of Nonvested Performance-Based Units Activity [Table Text Block]

	Number of Shares			Weighted Average Fair Value
Outstanding as of December 31, 2021		158,297		$	37.44
Performance factor adjustment		2,125		$	32.53
Vested		(19,125	)	$	32.53
Forfeited and cancelled		(23,400	)	$	41.86
Outstanding as of March 31, 2022		117,897		$	34.98