Dynamic fault collapsing and diagnostic test pattern generation for sequential circuits

We present results for significantly improving the performance of sequential circuit diagnostic test pattern generation (DATPG). Our improvements are achieved by developing results that permit dynamic, fully functional collapsing of candidate faults. Fault collapsing permits the organization of faults into disjoint partitions based on the indistinguishability relation. These results are used to develop a diagnostic test pattern generation algorithm that has the same order of complexity as that of detection oriented test generation (ATPG). Techniques to identify untestable faults, based on exploiting indistinguishability identification, are also presented. Experimental results are presented on the ISCAS 89 benchmark circuits.