LOW-COMPLEXITY FAULT SIMULATION UNDER THE MULTIPLE OBSERVATION TIME AND THE RESTRICTED MULTIPLE OBSERVATION TIME TESTING APPROACHES

The use of three-value logic for the fault simulation of synchronous s equential circuits may incur a loss of accuracy that would cause the f ault coverage to be underestimated. In addition, loss of fault coverag e may occur due to the test strategy employed. These problems were pre viously alleviated at the cost of a high computational complexity. We present an observation that allows us to alleviate loss of fault cover age in many cases, at a computational cost similar to conventional thr ee-value fault simulation. Based on this observation, we propose a fau lt simulation procedure that uses a conventional fault simulation proc edure enhanced by a simple implication procedure. The proposed fault s imulation procedure identifies faults that are detected under the mult iple observation time approach and under a special case of this approa ch, called the restricted multiple observation time approach. The resu lts of the proposed simulation procedure are compared to the results o f a previously proposed procedure to demonstrate its effectiveness. He uristics to guide a test generation procedure whose test sequences are effective for faults that can only be detected under the multiple obs ervation time approach are also described.