4. BALANCE SHEET DETAIL - Prepaid expenses and other current assets (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Mar. 31, 2019
Prepaid expenses and other current assets:
Prepaid tooling and masks	$ 988	$ 535
Prepaid income taxes	24	39
Escrow deposit		1,000
Other receivables	273	321
Other prepaid expenses and other current assets	1,263	605
Total prepaid expenses and other current assets	$ 2,548	$ 2,500