Defect-oriented module-level fault diagnosis in digital circuits

We propose a hierarchical approach for physical defect diagnosis in combinational or full scan-path digital circuits represented as module networks. As modules we may consider arbitrary subcircuits or library components (e.g. complex gates) of digital circuits. Both, cause-effect and effect-cause approaches are exploited intermittently. The higher level fault diagnosis is carried out in two phases. In the first phase, faulty modules are located by cause-effect analysis using high-level faulty module dictionary. The size of the dictionary depends linearly on the number of modules in the circuit. In the second phase, the set of suspected faulty modules is pruned by effect-cause indirect defect reasoning. At the lower level, the physical defects are directly located in suspected faulty modules. The proposed approach to fault diagnosis helps to cope with the growing complexities of digital circuits. The experimental results show high diagnostic resolution of the proposed approach.