Note 3 - Stock-based Compensation (Tables)

6 Months Ended

Sep. 30, 2020

Notes Tables

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

	Three Months Ended September 30,				Six Months Ended September 30,
	2020		2019		2020		2019
Cost of revenues	$	30	$	21	$	59	$	24
Research and development		161		92		291		103
Selling, general and administrative		658		283		1,408		519
Total	$	849	$	397	$	1,758	$	646

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

	Three Months Ended September 30,				Six Months Ended September 30,
	2020		2019		2020		2019
Expected volatility		N/A		N/A		N/A		66.5	%
Risk-free interest rate		N/A		N/A		N/A		1.8	%
Expected life (years)		N/A		N/A		N/A		5.91
Dividend yield		N/A		N/A		N/A	None