Generation of compact test sets with high defect coverage

Multi-detect (N-detect) testing suffers from the drawback that its test length grows linearly with N. We present a new method to generate compact test sets that provide high defect coverage. The proposed technique makes judicious use of a new pattern-quality metric based on the concept of output deviations. We select the most effective patterns from a large N-detect pattern repository, and guarantee a small test set as well as complete stuck-at coverage. Simulation results for benchmark circuits show that with a compact, 1-detect stuck-at test set, the proposed method provides considerably higher transition-fault coverage and coverage ramp-up compared to another recently-published method. Moreover, in all cases, the proposed method either outperforms or is as effective as the competing approach in terms of bridging-fault coverage and the surrogate BCE+ metric. In many cases, higher transition-fault coverage is obtained than much larger N-detect test sets for several values of N. Finally, our results provide the insight that, instead of using N-detect testing with as large N as possible, it is more efficient to combine the output deviations metric with multi-detect testing to get high-quality, compact test sets.