Simulation of Power Grid Networks Considering Wires and Lognormal Leakage Current Variations

As the technology scales into 90 nm and below, process-induced variations become more pronounced. In this paper, we propose an efficient stochastic method for analyzing the voltage drop variations of on-chip power grid networks, considering both wire and log-normal leakage current variations. The new analysis is based on the Hermite polynomial chaos (PC) representation of random processes. Different from the existing Hermite PC based method for power grid analysis, which considers only wire variations and model all the random variations as Gaussian processes. The new method considers both wire variations and leakage current variations. We model the variational sub-threshold leakage currents as log-normal distribution random variables. Our experiment results show that the new method is more accurate than the Gaussian-only Hermite PC method using the Taylor expansion method for analyzing leakage current variations, and two orders of magnitude faster than the Monte Carlo method with small variance errors

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