Note 9 - Segment and Geographic Information - Summary of Net Sales to Customers, Attributed to Countries (Details) - USD ($) $ in Thousands	3 Months Ended																12 Months Ended
	Dec. 28, 2019	[1]	Sep. 28, 2019	[1]	Jun. 29, 2019	[1]	Mar. 30, 2019	[1]	Dec. 29, 2018	[1]	Sep. 29, 2018	[1]	Jun. 30, 2018	[1]	Mar. 31, 2018	[1]	Dec. 28, 2019	Dec. 29, 2018	Dec. 30, 2017
Net sales	$ 142,011		$ 143,498		$ 150,011		$ 147,809		$ 170,637		$ 86,164		$ 99,817		$ 95,150		$ 583,329	$ 451,768	$ 352,704
CHINA
Net sales																	118,213	90,255	82,474
Malaysia [Member]
Net sales																	61,826	61,793	80,102
UNITED STATES
Net sales																	71,963	61,177	38,729
PHILIPPINES
Net sales																	51,683	46,421	26,268
TAIWAN, PROVINCE OF CHINA
Net sales																	75,725	25,074	16,517
Rest of the World [Member]
Net sales																	$ 203,919	$ 167,048	$ 108,614

[1] All quarters presented above were comprised of 13 weeks. We acquired Xcerra on October 1, 2018. The results of Xcerra have been included in our results of operations from the date of acquisition. See Note 2, “Business Acquisitions” for additional information regarding this transaction. Total operating expenses in 2019 and 2018 include acquisition costs and amounts related to the integration and our announced restructuring plan as follows. The fourth quarter of 2018 includes $19.1 million of inventory write-offs, $14.8 million of amortization of inventory step-up, and $18.7 million of restructuring charges. The first quarter of 2019 includes $6.0 million of amortization of inventory step-up. The second quarter of 2019 includes $8.5 million of restructuring charges.