Debt (Tables)

9 Months Ended

Sep. 30, 2018

Components of Convertible Senior Notes

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

	September 30, 2018		December 31, 2017
	(in thousands)
Debt Principal	$	460,000	$	460,000
Unamortized discount		83,583		94,013
Net Carrying amount of convertible debt	$	376,417	$	365,987

	For the Three Months Ended				For the Nine Months Ended
	September 30, 2018		October 1, 2017		September 30, 2018		October 1, 2017
	(in thousands)
Contractual interest expense on the coupon	$	1,438	$	1,422	$	4,313	$	4,297
Amortization of the discount component and debt issue fees recognized as interest expense		3,520		3,350		10,431		9,926
Total interest expense on the convertible debt	$	4,958	$	4,772	$	14,744	$	14,223