Improving Error Resilience for Compressed Test Sets by Don´t Care Assignment

Error-resilience is related to the capability of a compressed test data stream (which is transferred from an automatic test equipment (ATE) to the device-under-test (DUT)) to tolerate bit-flips. The bit-flips may occur in an ATE in the electronics components of the loadboard. As reported in (Hashempour et al., 2005), 10%-30% loss in the fault coverage of compressed test streams can occur due to bit flips for ISCAS89 benchmark circuits. This paper presents a novel technique based on don´t care assignment (prior to compression) to improve the error-resilience of a compressed test stream. Experimental results substantiate its effectiveness: fault coverage loss was contained to only 0.5%-6% compared to (Hashempour et al., 2005)