Note 12 - Equity Incentive Plans and Employee Benefits - Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
Jan. 28, 2017	Jan. 30, 2016	Jan. 31, 2015
Allocated Share-based Compensation Expense	$ 6,505	$ 6,559	$ 6,279
Cost of Sales [Member]
Allocated Share-based Compensation Expense	294	227	190
Research and Development Expense [Member]
Allocated Share-based Compensation Expense	3,452	3,241	3,147
Selling and Marketing Expense [Member]
Allocated Share-based Compensation Expense	1,197	1,151	979
General and Administrative Expense [Member]
Allocated Share-based Compensation Expense	$ 1,562	$ 1,940	$ 1,963

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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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration