CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Cash flows from operating activities:
Net income	$ 3,765	$ 217
Adjustments to reconcile net income to net cash used in operating activities:
Depreciation and amortization	1,596	993
Amortization of marketable securities premium	15	10
Stock-based compensation	816	643
Loss on disposal of equipment	2
(Gain) loss from equity method investments, net	(1,111)	120
Changes in operating assets and liabilities:
Accounts receivable	(3,886)	(4,691)
Inventories	(3,243)	354
Prepaid expenses and other current assets	(2,818)	(2,042)
Other assets	135	(1,383)
Accounts payable	745	(484)
Accrued liabilities	(4,018)	(1,388)
Other long-term liabilities, including royalties	(307)	1,547
Net cash used in operating activities	(8,309)	(6,104)
Cash flows from investing activities:
Purchases of property, plant and equipment	(5,776)	(2,139)
Proceeds from sales and maturities of available-for-sale debt securities	240	720
Net cash used in investing activities	(5,536)	(1,419)
Cash flows from financing activities:
Proceeds from common stock options exercised	704	441
Proceeds from short-term loan		391
Proceeds from sale of subsidiary shares to noncontrolling interests	538
Formation of new subsidiary with noncontrolling interests	642
Proceeds from issuance of Tongmei's common stock to redeemable noncontrolling interests, net of issuance costs	730
Net cash provided by financing activities	2,614	832
Effect of exchange rate changes on cash and cash equivalents	(165)	(140)
Net decrease in cash and cash equivalents	(11,396)	(6,831)
Cash and cash equivalents at the beginning of the year	72,602	26,892
Cash and cash equivalents at the end of the year	61,206	$ 20,061
Supplemental disclosure of non-cash flow information:
Consideration payable to repurchase subsidiary shares from noncontrolling interests, included in accrued liabilities	$ 3,730