Note 4 - Balance Sheet Components - Property and Equipment (Details) - USD ($) $ in Thousands	Sep. 26, 2020	Dec. 28, 2019
Total property and equipment, net	$ 39,782	$ 39,230
UNITED STATES
Total property and equipment, net	29,830	32,313
CHINA
Total property and equipment, net	1,390	1,683
PHILIPPINES
Total property and equipment, net	2,589	2,683
TAIWAN, PROVINCE OF CHINA
Total property and equipment, net	5,224	1,885
JAPAN
Total property and equipment, net	555	283
Other [Member]
Total property and equipment, net	194	383
Non-US [Member]
Total property and equipment, net	$ 9,952	$ 6,917