Generating single-stuck-fault coverage from a collapsed-fault set

Fault simulators do not simulate all the single stuck faults (SSFs), because as the simulated fault set grows, the increase in their runtime and memory requirements is greater than linear. Fault-set size is reduced, or collapsed, during circuit preprocessing by using the concepts of equivalence and dominance. It is shown that collapsed-fault (CF) coverage is not the same as SSF coverage and that this difference has a large effect on the defect level as the coverage approaches 100%. A very-low-overhead technique is presented that calculates true fault coverage while simulating with a CF set, thereby retaining the runtime and memory savings of simulating with CFs without sacrificing fault-coverage accuracy. This technique can be applied to any fault model exhibiting equivalence and dominance properties. The results are confirmed by benchmark results.<
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