CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Cash flows from operating activities
Net loss	$ (3,303)	$ (10,692)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	4,062	6,381
Stock-based compensation expense	2,615	3,277
Deferred taxes	356	344
Others	169	108
Gain on sale of assets and other write-offs	(116)	(17)
Write-down of inventories	2,659	2,267
Amortization of operating lease right-of-use assets	512	508
Foreign currency remeasurement	(416)	(968)
Change in operating assets and liabilities:
Accounts receivable	(8,515)	5,255
Inventories	(10,046)	(2,260)
Prepaid expenses and other assets	(4,407)	3,441
Accounts payable	2,771	(5,526)
Accrued and other liabilities	2,220	(11,062)
Net cash used in operating activities	(11,439)	(8,944)
Cash flows from investing activities
Purchase of property, plant and equipment	(2,043)	(1,908)
Proceeds from sale of property, plant and equipment and other assets	197	358
Purchase of marketable securities	(17,002)	(13,503)
Proceeds from sale of marketable securities	17,000	13,501
Net cash used in investing activities	(1,848)	(1,552)
Cash flows from financing activities
Proceeds from exercise of stock options and issuance of stock under ESPP	351	1,548
Tax withholding on restricted stock units	(48)	(1,835)
Proceeds from related party term loan, net of debt issuance costs	29,941	0
Repayment of bank loans	(15,635)	(794)
Repayment of finance lease liabilities	(25)	(24)
Net cash provided by (used in) financing activities	14,584	(1,105)
Effect of exchange rates on cash, cash equivalents and restricted cash	(86)	(449)
Net increase (decrease) in cash, cash equivalents and restricted cash	1,211	(12,050)
Cash, cash equivalents and restricted cash at the beginning of the period	77,920	95,606
Cash, cash equivalents and restricted cash at the end of the period	79,131	83,556
Supplemental disclosure of non-cash investing and financing activities:
Unpaid property, plant and equipment in accounts payable	$ 2,564	$ 862