In this paper we present an input pattern independent method to compute the maximum current envelope, which is an upper bound over all possible current waveforms drawn by a circuit. The maximum current envelope can be used to compute the worst-case RMS current and average current drawn by a set of gates. These current values can be used in the design of the power bus to ensure that the power bus interconnects are not susceptible to electromigration EM induced failure. We also present comparisons with exhaustive long simulations for MCNC ISCAS-85 benchmark circuits to verify the accuracy of the method.
Sudhakar Bobba, Ibrahim N. Hajj