Monitoring BIST by covers

The authors show how to combine a conventional built-in self-test method with a simple method for online error detection for combinational circuits. The output sequence of one or more components of the signature analyzer is monitored, in test mode, by an error detection circuit consisting of a one-cover and a zero-cover. The cover circuits need to detect only such faults that are masked by the signature analyzer. Because of a large number of don't-care conditions for the cover circuits the hardware overhead is very low. All faults in the fault model under consideration are detected either by the cover circuits or, due to an erroneous signature, by the signature analyzer.<
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