Graph partition based path selection for testing of small delay defects

Critical path selection plays an important role in testing of small delay defects (SDD). For some timing-balanced circuits, the numbers of candidate critical paths may be very large, and this will make Monte Carlo simulation based statistical timing analysis very inefficient. A fast path selection approach based on graph partition is proposed in this paper. First, a critical path graph (CPG) is generated to implicitly enumerate almost all candidate critical paths, and then the CPG is partitioned into several sub graphs which contain limited numbers of paths using two graph partition approaches. After that, Monte Carlo simulation is applied on each sub graph for path selection. At last, according to the partition topology of the CPG and path sets selected from each sub graph, a path set for the original CPG is generated using Union and Cartesian product operations for testing SDDs. Experimental results show that for circuits containing large numbers of candidate critical paths, the proposed path selection approach can reduce the CPU time significantly and maintain a higher probability of capturing delay failures compared to path selection methods based on general Monte Carlo simulation.