A Hybrid Method for Signal Probability Estimation with Combinational Circuits

Signal probability is one of the most important factors in evaluating the performance of digital circuits. However, estimating signal probability for large circuits could be difficult due to signal delay and/or complex signal correlations caused by reconvergent fanouts. In this paper, we propose a hybrid approach to estimate signal probability by categorizing the strength of signal correlations in order to propagate signal probabilities through logic gates. Probabilities for signals with strong correlation are calculated directly and accurately, while those with relatively-weak correlations are evaluated using local bit-stream simulations. Simulation results on benchmark circuits show that the proposed method is both efficient and effective with a high level of accuracy.