Accurate Estimation of Combinational Circuit Activity

Several techniques to estimate power consumption of a combinational circuit using probabilistic methods have been proposed. However none of these techniques take into account circuit activity when two or more inputs change simultaneously or when glitching occurs. A formulation is presented in this paper which includes signal correlation and multiple gate input switching. Work is also presented in estimating the glitching contribution to the switching activity. Results obtained from benchmarks and test circuits show very good accuracy when compared to actual activities as measured by SPICE and IRSIM.