Concurrent on-line testing of identical circuits through output comparison using non-identical input vectors

Current designs may contain several identical copies of the same circuit (or functional unit). Such circuits can be tested by comparing the output vectors they produce under identical input vectors. This alleviates the need to observe the output response, and facilitates on-line testing. We show that testing of identical circuits by output comparison can be done effectively even when the input vectors applied to the circuits are not identical. This allows concurrent on-line testing even when the circuits are not driven front the same source during functional operation. We present experimental results to support the use of nonidentical input vectors for concurrent on-line testing of identical circuits.