Intangible Assets (Tables)

3 Months Ended

Mar. 31, 2021

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of carrying value of intangible assets

The carrying values of intangible assets as of the dates presented, respectively, consists of the following (in thousands except years):

	March 31, 2021
	Gross		Accumulated Amortization		Foreign Exchange Rate Changes		Net		Estimated Useful Life (in years)
Patents	$	2,963	$	(2,049)	$	—	$	914	10
Developed technology - 150V	560		(517)		(43)		—		6
Developed technology - 600V	1,701		(1,570)		(131)		—		6
Total	$	5,224	$	(4,136)	$	(174)	$	914
	December 31, 2020
	Gross		Accumulated Amortization		Foreign Exchange Rate Changes		Net		Estimated Useful Life (in years)
Patents	$	2,963	$	(1,975)	$	—	$	988	10
Developed technology - 150V	560		(555)		(5)		—		6
Developed technology - 600V	1,701		(1,684)		(17)		—		6
Total	$	5,224	$	(4,214)	$	(22)	$	988
	December 31, 2019
	Gross		Accumulated Amortization		Foreign Exchange Rate Changes		Net		Estimated Useful Life (in years)
Patents	$	2,963	$	(1,679)	$	—	$	1,284	10
Developed technology - 150V	560		(519)		(34)		7		6
Developed technology - 600V	1,701		(1,575)		(104)		22		6
Total	$	5,224	$	(3,773)	$	(138)	$	1,313

Schedule of estimated future amortization expenses related to intangible assets

Estimated future amortization expenses related to intangible assets as of March 31, 2021 were as follows (in thousands):

2022	$	296
2023	296
2024	296
2025	26
Thereafter	—
Total	$	914