The Company uses the Black-Scholes option pricing model to calculate the fair value of stock option awards, whether they possess time-based vesting provisions or performance-based vesting provisions, and awards granted under the Vicor Corporation 2017 Employee Stock Purchase Plan (“ESPP”), as of their grant date. Stock-based compensation expense was as follows (in thousands):


	Three Months Ended
	March 31,
	2024		2023
Cost of revenues	$	754	$	486
Selling, general and administrative		1,919		1,520
Research and development		1,107		811
Total stock-based compensation	$	3,780	$	2,817

Compensation expense by type of award was as follows (in thousands):


	Three Months Ended
	March 31,
	2024		2023
Stock options	$	3,466	$	2,496
ESPP		314		321
Total stock-based compensation	$	3,780	$	2,817