Upper bounding fault coverage by structural analysis and signal monitoring

A new algorithm for identifying stuck faults in combinational circuits that cannot be detected by a given input sequence is presented. Other than pre and post-processing steps, certain signal conditions are monitored during logic simulation. These signal conditions are specified by an analysis of dominators and signal reconvergences in the circuit graph. After simulation, a post-processing step identifies faults that cannot be detected by the sequence. For combinational IS GAS benchmarks, the runtime overhead for the algorithm is found to be around 30-40% over that of a logic simulator. Experimental data show a substantial reduction of error in statistical estimates obtained by a stuck-fault coverage estimator when corrected for faults found by this algorithm as guaranteed to be undetected by the given sequence. An effective application of this technique is demonstrated for scan-based test point selection in an industrial scenario where circuit size and vector length prohibit the use of fault simulation