Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Cash flows from operating activities:
Net loss	$ (6,607)	$ (9,342)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities
Depreciation and amortization expense	8,273	7,413
Non-cash operating lease cost and other	1,380
Stock-based compensation expense	1,379	831
Inventory write-down	321	9,165
Changes in assets and liabilities:
Accounts receivable, net	1,521	1,688
Related party accounts receivable	363	326
Inventories	8,144	(13,982)
Prepaid expenses and other current assets	(3,145)	2,572
Accounts payable	(1,148)	(648)
Accrued expenses and other liabilities	(919)	1,122
Lease liabilities	(2,184)
Other assets and liabilities		(191)
Net cash provided by (used in) operating activities	7,378	(1,046)
Cash flows from investing activities
Purchase of property and equipment	(1,426)	(2,314)
Cash paid for intangibles	(1,776)	(2,698)
Net cash used in investing activities	(3,202)	(5,012)
Cash flows from financing activities
Proceeds from initial public offering, net of underwriting discounts and commissions and other offering costs	56,353
Proceeds from loans from financial institutions		21,000
Proceeds from investment from MegaChips		1,850
Principal payments on loan to MegaChips	(3,000)
Principal payments on loan to financial institutions	(2,000)	(18,000)
Net cash provided by financing activities	51,353	4,850
Net increase (decrease) in cash and cash equivalents	55,529	(1,208)
Cash and cash equivalents
Beginning of period	7,889	9,097
End of period	63,418	7,889
Supplemental disclosure of cash flow information
Interest paid during the period	2,167	1,310
Income taxes paid	1	1
Supplemental disclosure of noncash flow information
Unpaid property and equipment	77	61
Unpaid intangibles	$ 558	$ 1,116