Recovery during concurrent on-line testing of identical circuits

We show that a concurrent online testing scheme based on output comparison of identical circuits can also identify situations where the circuit recovers from a permanent fault, i.e., functional operation can continue temporarily in spite of the presence of a fault. We show that the ability to recover from a fault is circuit-dependent, and that some circuits are better than others at allowing recovery. We also discuss the possibility of false recovery in the presence of multiple faults and its implications.