Improved single-pass approach for reliability analysis of digital combinational circuits

Designing a highly reliable digital circuit requires tools and techniques for accurately evaluation of its reliability. In this paper, we present an improved single-pass approach for reliability analysis of digital combinational circuits. The main problem of the basic single-pass method is handling reconvergent fan-outs. The proposed method improves the accuracy of the basic single-pass method in two ways. An efficient method is proposed to compute the joint probability between multiple nodes of the circuit which leads to more accurate calculation of correlation coefficients. The second enhancement consists of two methods called case based and mathematical based and concentrates on accurate calculation of conditional joint correlations which makes the algorithm much more dependable than the basic single-pass method. The case based method checks different conditions of the nodes for calculation of conditional joint correlations, while the mathematical based method uses a heuristic expression. The proposed method is applied to a subset of combinational benchmark circuits and our experiments demonstrate that the proposed method eliminates the weaknesses of the basic single-pass method efficiently.