Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 28, 2019	Sep. 29, 2018
Cash flows from operating activities:
Net income	$ 20,710	$ 18,936
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	12,644	10,494
Amortization	20,248	21,876
Amortization (accretion) of discount on investments	(291)	21
Amortization of operating lease, right-of-use assets	3,921	0
Stock-based compensation expense	17,088	12,421
Amortization of debt issuance costs	132	333
Deferred income tax provision	38	70
Provision for excess and obsolete inventories	8,046	7,414
Loss on disposal of long-lived assets	327	264
Loss on derivative instruments	132	0
Foreign currency transaction (losses) gains	(186)	409
Changes in assets and liabilities:
Accounts receivable	10,580	(7,569)
Inventories	(17,246)	(21,806)
Prepaid expenses and other current assets	(4,509)	(1,874)
Refundable income taxes	782	933
Other assets	(595)	697
Accounts payable	10,074	10,425
Accrued liabilities	(856)	(8,882)
Other liabilities	2,374	2,197
Deferred revenues	3,625	(221)
Operating lease liabilities	(3,660)	0
Net cash provided by operating activities	83,378	46,138
Net cash provided by operating activities
Acquisition of property, plant and equipment	(14,242)	(12,326)
Proceeds from sale of a subsidiary	93	67
Proceeds from sale of property, plant and equipment	0	23
Purchases of marketable securities	(59,602)	(18,984)
Purchases of marketable securities	33,704	17,757
Net cash used in investing activities	(40,047)	(13,463)
Net cash used in investing activities
Cash flows from financing activities:	7,672	7,712
Purchase and retirement of common stock	(7,898)	(5,694)
Proceeds from term loan debt	(18,750)	(33,750)
Payment of term loan debt issuance costs	(18,976)	(31,732)
Net cash used in financing activities	(161)	(516)
Effect of exchange rate changes on cash, cash equivalents and restricted cash	24,194	427
Net increase in cash, cash equivalents and restricted cash	100,546	92,726
Cash, cash equivalents and restricted cash, beginning of period	124,740	93,153
Fair value of stock options and restricted stock-based awards assumed in connection with acquisition of Cascade Microtech
Change in accounts payable and accrued liabilities related to property, plant and equipment purchases	1,062	4,724
Operating lease, right-of-use assets obtained in exchange for lease obligations	36,300	0
Supplemental disclosure of cash flow information:
Cash paid for income taxes, net	2,875	2,513
Cash paid for interest	$ 1,128	$ 2,299