A diagnostic test generation system and a coverage metric

A diagnostic automatic test pattern generation (DATPG) system is constructed by adding new algorithmic capabilities to conventional ATPG and fault simulation programs. The system generates tests to distinguish between fault pairs through different output responses. Given a fault pair, by modifying circuit netlist a new single fault is modeled and targeted for detection by a conventional ATPG. The test distinguishes the given fault pair. In the fault simulator faults are partitioned into different groups according to their output responses. Thus, fault pairs that a simulated vector can distinguish between are split among separate groups. Faults that form single-fault groups are dropped from further simulation. Using a proposed diagnostic coverage (DC) metric, we observe improved DC in most benchmark circuits. Cases of low DC have helped identify new open problems.