Reducing Output Response Aliasing Using Boolean Optimization Techniques

In digital circuit testing, output response compaction can have a significant impact on fault coverage. The loss of fault coverage is caused by aliasing in the output response compaction. Classical approaches to reducing (eliminating) fault aliasing are based on modifications of the compactor design or modifying precomputed test sequence. In this paper, we propose a completely different approach based on a dedicated test pattern generation algorithm. The algorithm generates a test sequence with minimal aliasing for targeted faults. As the generated test sequence is tailored to given static and dynamic compactor structures, any response compactor can be used without a change in the design. We expand on our previous work, zero-aliasing ATPG, and incorporate pseudo-Boolean optimization techniques in the process.The algorithm is evaluated using an LFSR-based MISR on a selection of benchmark circuits. A comparison with a state-of-the-art ATPG process without anti-aliasing measures is drawn.