The below tables represent the key components of Teradyne’s convertible senior notes:


	April 1, 2018		December 31, 2017
	(in thousands)
Debt Principal	$	460,000	$	460,000
Unamortized discount		90,579		94,013

Net Carrying amount of convertible debt	$	369,421	$	365,987


	For the Three Months Ended
	April 1, 2018		April 2, 2017
	(in thousands)
Contractual interest expense on the coupon	$	1,438	$	1,438
Amortization of the discount component and debt issue fees recognized as interest expense		3,434		3,268

Total interest expense on the convertible debt	$	4,872	$	4,706