Delay models for MCM interconnects when response is nonmonotone

Abstract

Elmore delay has been extensively used for interconnect delay estimation because its simplicity of evaluation makes it appropriate for layout design. However, since Elmore delay does not take into account the effect of inductance, the discrepancy between actual delay and Elmore delay becomes significant for long RLC transmission lines, such as for MCM and PCB interconnects. We describe a simple two-pole based analytic delay model that estimates arbitrary threshold delays for RLC lines when the response is nonmonotone; our model is far more accurate than the Elmore model. We also describe an application of our model for controlling response undershoot/overshoot and for the reduction of interconnect delay through constraints on the moments.