Table-lookup methods for improved performance-driven routing

Abstract

The inaccuracy of Elmore delay for interconnect delay estimation is well-documented. However it remains a popular delay measure to drive performance optimization procedures such as wire-sizing and topology construction. This paper studies the merits of incorporating "better-than-Elmore" delay measures into the optimization process. The proposed delay metrics use a table-lookup method to incorporate better load modeling and approximate the effect of signal slew. We demonstrate that the proposed metrics exhibit a much narrower error distribution than Elmore delay, eliminating Elmore's frequent gross delay over-estimation. Finally we show the improvement in solution quality which can be had by incorporating the new metrics into a timing driven topology construction algorithm.