B. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - VARIOUS POLICIES (Details)	12 Months Ended
	Dec. 31, 2017 USD ($) patent	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Cash and cash equivalents	$ 82,936,000	$ 50,224,000
Cash in excess of FDIC insurance	58,800,000
Percentage of bank acceptance notes and standy letters of credit	30
Restricted cash	$ 1,012,000	1,732,000
Number of years of land use rights	50 years
Number of patents | patent	241
Weighted average amortization period	8 years
Accrued product warranty	$ 1,118,000	705,000
Advertising Costs	300,000	$ 200,000	$ 100,000
ASU 2016-09
Windfall tax benefits	1,200,000
Retained earnings	$ 10,000
Patents
Weighted average amortization period	20 years
Sales Revenue, Net [Member] | Five Customers [Member]
Concentration of credit risk	86.10%	87.80%	81.80%
Sales Revenue, Net [Member] | Amazon [Member]
Concentration of credit risk	35.40%	54.60%	52.50%
Sales Revenue, Net [Member] | Facebook [Member]
Concentration of credit risk	28.60%
Sales Revenue, Net [Member] | Microsoft [Member]
Concentration of credit risk	13.80%	18.30%	11.60%
Sales Revenue, Net [Member] | Cisco [Member]
Concentration of credit risk			10.40%
Sales Revenue, Net [Member] | Arris [Member]
Concentration of credit risk		5.80%
Accounts Receivable [Member] | Five Customers [Member]
Concentration of credit risk	82.60%	88.30%
Accounts Receivable [Member] | Amazon [Member]
Concentration of credit risk	36.10%	62.10%
Accounts Receivable [Member] | Microsoft [Member]
Concentration of credit risk	19.50%
Accounts Receivable [Member] | Arris [Member]
Concentration of credit risk		10.60%
Foreign Accounts [Member]
Cash and cash equivalents	$ 21,000,000	$ 10,700,000