Diagnosis for scan-based BIST: reaching deep into the signatures

For partitioning-based diagnosis in a scan-based BIST environment, an exact analysis scheme, capable of identifying all scan cells that receive incorrect data, is proposed. In contrast to previously suggested approaches, the scheme we propose identifies all failing scan cells with no ambiguity whatsoever. Not only do we resolve failing scan cells unambiguously, but we do so at the earliest possible instance through reexamination of already computed signatures. Intensive utilization of this highly precise diagnostic state information leads to prognostic information regarding the usefulness of running upcoming tests which in turn leads to reductions in diagnosis time in excess of 30% compared to previous approaches