244VLSI Test Principles and Architecturesthe faultdslow-to-fall, which can be detected byV1V4, has already been detectedby selecting the test chainV2V4V1. Therefore, the edgeV1V4can be removedfrom the weighted pattern graph because it no longer contributes to the detection ofother transition faults. Similar argument can be made for the edgeV3V1. Finally,all the seven originally undetected faults in Table 4.16 are detected with the testchainV2V4V1V3V4V126.96.36.199Bridging Fault ATPGRecall that bridging faults are those faults that involve a short between two signalsin the circuit. Given a circuit withnsignals, there are potentiallyn×n−1 possiblebridging faults. However, practically, only those signals that are locally close onthe die are more likely to be bridged. Therefore, the total number of bridging faultscan be reduced to be linear in the number of signals in the circuit.
This is the end of the preview.
access the rest of the document.