Note 11 - Stock-based Compensation - Stock-based Compensation Expense Related to Stock Options and RSUs (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Jan. 01, 2017	Dec. 27, 2015	Jan. 01, 2017	Dec. 27, 2015
Stock-based compensation expense	$ 3,634	$ 811	$ 7,131	$ 3,810
Cost of Sales [Member]
Stock-based compensation expense	474	98	889	257
Research and Development Expense [Member]
Stock-based compensation expense	926	117	1,696	509
Selling, General and Administrative Expenses [Member]
Stock-based compensation expense	$ 2,234	$ 596	$ 4,546	$ 3,044

Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 14.F)
-URI http://asc.fasb.org/extlink&oid=27013229&loc=d3e301413-122809

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5047-113901

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(1)(i)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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