Logic Circuits Testing for Transient Faults

Transient faults are becoming an increasingly serious concern for logic circuits. They can be caused by thermal neutrons, present at all altitudes, and by other types of ionizing radiation, especially in aerospace applications and nuclear engineering. In this paper we examine issues related to detection of transient errors. The difficulty in testing for transient errors is that they are not always present. Test vectors need to be repeated a number of times in order to detect a fault. We show how to compute a measure for the detectability of transient faults with respect to specific test vectors. This is done using a matrix-based gate-fault model known as the probabilistic transfer matrix model. Using this detectability measure we derive methods to generate multisets of tests to verify probability distributions of faults and detect abnormalities in circuit behavior. Applications of this method include detection of increased atmospheric radiation in terms of its impact on circuits, and testing for process variation that increases the susceptibility of a circuit to transient errors.