SST: scan self-test for sequential machines

A new scan, built-in self-test technique called SST for testing sequential machines (finite state machines) is presented. This technique uses an external linear feedback shift register (LFSR) or a cellular-automaton-based (CA-based) test pattern generator to generate exhaustive test patterns. These patterns are scanned into the machine and the output responses are scanned out for comparison. It is shown that SST provides exhaustive patterns for sequential machines, which is not the case using the BILBO technique or other pseudorandom techniques. SST yields shorter test lengths than BIST methods using checking experiments. The technique is well suited to test multiple scan-based sequential machines simultaneously. It does not require that scan paths be reconfigured as test pattern generators on the scan paths, and thus is also suitable for testing sequential machines using off-the-shelf (catalogue) components, such as PLAs or PALs.