Note 8 - Stock-based Compensation - Schedule of Allocation of Recognized Period Cost (Details) - USD ($) $ in Thousands	3 Months Ended
Apr. 04, 2021	Mar. 29, 2020
Total costs and expenses	$ 368	$ (398)
Cost of Sales [Member]
Total costs and expenses	36	12
Research and Development Expense [Member]
Total costs and expenses	157	(464)
Selling, General and Administrative Expenses [Member]
Total costs and expenses	$ 175	$ 54

Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
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-Section 50
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-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5047-113901

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
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-Paragraph 1
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
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-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

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