Note 11 - Employee Equity Incentive Plans - Allocated Share-based Compensation Expense (Details) - USD ($) $ in Thousands		3 Months Ended
		Jun. 30, 2016	Jun. 30, 2015
Cost of Sales [Member]
Stock-based Compensation Effect in Income before Taxes		$ 100	$ 122
Research and Development Expense [Member]
Stock-based Compensation Effect in Income before Taxes		303	460	[1]
Selling, General and Administrative Expenses [Member]
Stock-based Compensation Effect in Income before Taxes		452	406
Stock-based Compensation Effect in Income before Taxes		855	988
Provision for income taxes	[2]	342	346
Net stock-based compensation effects in net income		$ 513	$ 642

[1] Includes acquisition related compensation expenses of $249,000 during the quarter ended June 30, 2015.

[2] Calculated at the U.S. statutory federal income tax rate of 40% in fiscal 2017 and 35% in fiscal 2016.