CMOS Stuck-Open Fault Detection Using Single Test Patterns

CMOS combinational circuits exhibit sequential behavior in the presence of open faults, thus making it necessary to use two pattern tests. Two or multi-pattern sequences may fail to detect CMOS stuck-open faults in the presence of glitches. The available methods for augmenting CMOS gates to test CMOS stuck-open faults, are found to be inadequate in the presence of glitches. A new CMOS testable design is presented. The scheme uses two additional MOSFETs, which convert a CMOS gate to either pseudo nMOS or pseudo pMOS gate during testing. The proposed design ensures the detection of stuck-open faults using a single vector during testing.