Diagnostic Test Set Minimization and Full-Response Fault Dictionary

Abstract

We minimize a given test set without loss of diagnostic resolution in full-response fault dictionary. An integer linear program (ILP), formulated from fault simulation data, provides ultimate reduction of test vectors while preserving fault coverage and pair-wise distinguishability of faults. The complexity of the ILP is made manageable by two innovations. First, we define a generalized independence relation between pairs of faults to reduce the number of fault pairs that need to be distinguished. This significantly reduces the number of ILP constraints. Second, we propose a two-phase ILP approach. In the first phase, using an existing procedure, we select a minimal detection test set. In the second phase, additional tests are selected for the undiagnosed faults using a newly formulated diagnostic ILP. The overall minimized test set may be only slightly longer than a one-step ILP optimization, but has advantages of reducing the minimization problem complexity and the test time required by the minimized tests. Benchmark results show potential for significantly smaller diagnostic test sets.