Intermittent Faults: A Model and a Detection Procedure

Intermittent faults are those faults whose effects on the behavior of a system are present only part of the time. A probabilistic model for intermittent faults in digital circuits is suggested. A procedure for the detection of such faults in combinational circuits is proposed. The procedure employs the repeated application of tests that test for these faults as if their effects were permanent. The procedure is analogous to a sequential statistical decision problem. Least upper bounds on the number of repetitions of tests that detect a particular fault are derived. These bounds are then employed in designing optimum detection experiments. Such an optimization problem is found to be equivalent to an integer programming problem.