A fast, accurate, and non-statistical method for fault coverage estimation

We present a fast, dynamic fault coverage estimation technique for sequential circuits that achieves high degrees of accuracy by significantly reducing the number of injected faults and faulty-event evaluations. Specifically, we dynamically reduce injection of two types of faults: (1) hyperactive faults that never get detected, and (2) faults whose effects never propagate to a flip-flop or primary output. The cost of fault simulation is greatly reduced as injection of most of these two types of faults is prevented. Experiments show that our technique gives very accurate estimates with frequently greater speedups than the sampling techniques for most circuits. Most significantly, the proposed technique can be combined with the sampling approach to obtain speedups equivalent of small sample sizes and retain estimation accuracy of large fault samples.