REVENUE RECOGNITION - Narrative (Details) $ in Thousands					12 Months Ended
	Sep. 30, 2021 USD ($) specific_radio_frequency installment	Sep. 29, 2020 USD ($)	Oct. 11, 2019 USD ($)	Sep. 30, 2019 USD ($) specific_radio_frequency	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Nov. 10, 2021 USD ($)	Oct. 31, 2021 USD ($)	Dec. 31, 2019 USD ($)
Disaggregation of Revenue [Line Items]
Contracted exclusivity period					2 years
Deferred revenue					$ 6,796	$ 1,783			$ 1,731
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Disaggregation of Revenue [Line Items]
Deferred revenue to be recognized					$ 6,800
Deferred revenue to be recognized, period					4 years
Proprietary Circuit Designs using XBAR Technology | Murata Manufacturing Co., Ltd.
Disaggregation of Revenue [Line Items]
Number of licensed radio frequencies or bands | specific_radio_frequency	4			4
Prepaid royalties				$ 9,000
Written termination period	30 days			30 days
Contracted exclusivity period				30 months
Revenue from collaboration agreement					$ 1,600	$ 2,700
Number of licensed radio frequencies or bands | specific_radio_frequency	4
Deferred revenue	$ 4,000				$ 4,500		$ 3,000
Number of installments | installment	2
Contract with customer, payment per band	$ 1,000
Band design period	3 years
Total transaction price								$ 7,000
Proprietary Circuit Designs using XBAR Technology | Murata Manufacturing Co., Ltd. | Accounts Receivable
Disaggregation of Revenue [Line Items]
Revenue from collaboration agreement		$ 2,500	$ 2,000
Minimum
Disaggregation of Revenue [Line Items]
Recognition period					1 year
Minimum | Proprietary Circuit Designs using XBAR Technology | Murata Manufacturing Co., Ltd.
Disaggregation of Revenue [Line Items]
Prepaid royalties	$ 8,000
Maximum
Disaggregation of Revenue [Line Items]
Recognition period					4 years
Maximum | Proprietary Circuit Designs using XBAR Technology | Murata Manufacturing Co., Ltd.
Disaggregation of Revenue [Line Items]
Prepaid royalties	$ 36,000