On the guaranteed failing and working frequencies in path delay fault analysis

When running a set of test vectors to detect path delay faults in a digital system, desired test frequencies are needed. In this paper we determine the guaranteed failure frequency (GFF) and the guaranteed working frequency (GWF) for a given set of test vectors used for path delay testing of a sequential circuit. If the circuit passes the test when the vectors are applied at GFF, then all paths activated by those vectors are guaranteed to be free from delay faults provided the clock frequency does not exceed the GWF. Ambiguity cancellation and minmax-delay or statistical-delay modeling techniques are used in a timing simulation system to determine GFF and GWF. Experiments show that by using the guaranteed failure frequency, we can obtain the best (most reliable) path delay fault coverage provided by the given test vectors.