Note 11 - Customer and Geographic Information - Revenues by Geographic Area (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Revenues	$ 23,112	$ 21,914	$ 65,678	$ 63,023
Geographic Concentration Risk [Member] | Revenue Benchmark [Member]
Revenues	$ 23,112	$ 21,914	$ 65,678
Concentration risk	100.00%	100.00%	100.00%
Geographic Concentration Risk [Member] | Revenue Benchmark [Member] | UNITED STATES
Revenues	$ 7,710	$ 7,341	$ 26,242	$ 25,203
Concentration risk	33.00%	34.00%	40.00%	40.00%
Geographic Concentration Risk [Member] | Revenue Benchmark [Member] | CHINA
Revenues	$ 6,747	$ 5,118	$ 10,200	$ 11,369
Concentration risk	29.00%	23.00%	16.00%	18.00%
Geographic Concentration Risk [Member] | Revenue Benchmark [Member] | TAIWAN, PROVINCE OF CHINA
Revenues	$ 1,113	$ 2,423	$ 8,038	$ 6,041
Concentration risk	5.00%	11.00%	12.00%	10.00%
Geographic Concentration Risk [Member] | Revenue Benchmark [Member] | Rest of the World [Member]
Revenues	$ 7,542	$ 7,032	$ 21,198	$ 20,410
Concentration risk	33.00%	32.00%	32.00%	32.00%