The Fidelity Property of the Elmore Delay Model in actual comparison of routing algorithms

Abstract

Despite the existence of several other alternatives for estimating delay of interconnects, the Elmore Delay Model still has been used for comparison of routing algorithms. The criterion used to establish Elmore's model as a confident metric for this purpose is the so-called Fidelity Property. In this work we investigate the Fidelity Property using nowadays interconnect parameters, in four routing scopes. For the first time the Fidelity is evaluated in actual algorithms comparison, one of the main utilities it was established for. What is found is that the original methodology used to evaluate this property hides a significant standard deviation. This standard deviation strongly impacts the capacity of Elmore's model to provide good certainty of choosing the best routing solutions among several ones. Additionally, the experiments of algorithms comparison show that different routing alternatives are appropriated for different routing scopes, with respect to metal layers, driver strengths and routing areas.