Parallel Critical Path Tracing Fault Simulation in Sequential Circuits

In this paper we present a very fast fault simulation method for sequential circuits, which is based on accommodation of exact parallel critical path tracing in combinational circuits for using it also in case of sequential circuits. Formulas are developed for parallel on-line analysis of the faults to classify them into two classes, which are eligible for combinational simulation, and which are not. The latter class of faults has to be simulated by any conventional fault simulation method used for sequential circuits. Combining two approaches to fault simulation - the combinational and sequential ones - allows dramatic speed-up of fault simulation in sequential circuits, which is demonstrated by experimental results.