Gate-level power estimation using tagged probabilistic simulation

In this paper, we present a probabilistic simulation technique to estimate the power consumption of a CMOS circuit under a general delay model. This technique is based on the notion of a tagged (probability) waveform, which models the set of all possible events at the output of each circuit node. Tagged waveforms are obtained by partitioning the logic waveform space of a circuit node according to the initial and final values of each logic waveform and compacting all logic waveforms in each partition by a single tagged waveform. To improve the efficiency of tagged probabilistic simulation, only tagged waveforms at the circuit inputs are exactly computed. The tagged waveforms of the remaining nodes are computed using a compositional scheme that propagates the tagged waveforms from circuit inputs to circuit outputs. We obtain significant speed up over explicit simulation methods with an average error of only 6%. This also represents a factor of 2-3/spl times/ improvement in accuracy of power estimates over previous probabilistic simulation approaches.