METHOD AND APPARATUS FOR COMBINED STUCK-AT FAULT AND PARTIAL-SCANNED DELAY-FAULT BUILT-IN SELF TEST

摘要

This invention relates to a method and apparatus for combined stuck-fault testing and partial scan delay-fault built-in self testing (BIST) (20). For partial scan delay-fault (BIST) (20), the circuit is modeled for breaking all flip-flop feedback cycles in the circuit. A selection of flip-flops to be scanned to break all sequential cycles is determined from an optimal feedback vertex set. A digest, devour and tidy-up (DDT) (4C) heuristic can be used on a weighted signed graph formed from an S-graph of the circuit to determine an optimal feedback vertex set. Determined partial scan delay fault (BIST) (20) hazards can be removed from the circuit by inserting parity flippers to invert selected paths during testing. The same (DDT) (4C) heuristic can be used to determine optimal placement of the parity flippers in the circuit.