Delay analysis of the distributed RC line

Abstract

This paper reviews the step-response of the semi-infinite distributed RC line and focuses mainly on the step-response of a finite-length RC line with a capacitive load termination, which is the most common model for a wire inside the present day integrated CMOS chips. In particular, we obtain the values of some of the common threshold-crossing times at the output of such a line and show that even the simplest first order lumped II-approximation to the finite-length RC line terminated with a capacitive load is good enough for obtaining the 50% and 63.2% threshold-crossing times of the step-response. Higher order lumped approximations are necessary for more accurate predictions of the 10% and 90% threshold-crossing times.