Note 3 - Stock-based Compensation (Tables)

9 Months Ended

Dec. 31, 2019

Notes Tables

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

	Three Months Ended December 31,				Nine Months Ended December 31,
	2019		2018		2019		2018
Cost of revenues	$	21	$	42	$	45	$	132
Research and development		117		168		219		289
Selling, general and administrative		452		582		971		1,981
Total	$	590	$	792	$	1,236	$	2,402

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

	Three Months Ended December 31,				Nine Months Ended December 31,
	2019		2018		2019			2018
Expected volatility		N/A		N/A		66.5	%		N/A
Risk-free interest rate		N/A		N/A		1.8	%		N/A
Expected life (years)		N/A		N/A		5.91			N/A
Dividend yield	N/A			N/A	None				N/A