A unified test architecture for on-line and off-line delay fault detections

This paper proposes a unified delay test architecture, in which the design resources for on-line delay fault detection can be reused to support off-line delay testing. A stability checker, which has low hardware overhead, is presented to monitor the stability violation from each critical combinational output. A global error generator, which is shared among stability checkers, can produce a global error signal from individual stability checkers to indicate whether a delay fault appears. A local scan enable generator is incorporated into the scan chain to support scan-based off-line delay testing. Experimental results are presented to validate the effectiveness of the proposed approach.