S2P: A Stable 2-Pole RC Delay and Coupling Noise Metric1

The Elmore delay is the metric of choice for performancedriven design applications due to its simple, explicit form and ease with which sensitivity information can be calculated. However, for deep submicron technologies, the accuracy of the Elmore delay is insufficient. In this paper, we formulate a delay model using a provably stable two pole waveform response that provides a unique mapping between four moments and a specific delay value. Unlike traditional moment matching, this two-pole model permits us to precharacterize the delays, and store them in a table, as a mapped function of three parameters. The model also provides an explicit expression for the peak noise induced on a coupled line as a function of the same three moments. The results indicate runtimes comparable to an Elmore delay calculation but with the accuracy of an AWE approximation.