Design and test rules for CMOS circuits to facilitate IDDQ testing of bridging faults

摘要

All possible bridging faults (BFs) between any two circuit nodes are considered, where a circuit node may be the drain, source, or gate terminal of a transistor. Several examples are given to show that under certain circumstances current supply monitoring (CSM) cannot give correct test results. A circuit partitioning model is described, and a minimal set of design and test rules is presented. This set of rules is minimal in the sense that if any one of these rules is removed, then circuits exist for which CSM cannot give correct test results. When all the rules are satisfied it can be formally shown that: (1) all signal irredundant BFs can be detected by single vector tests, and (2) a test vector that detects a single bridging fault f/sub 1/ also detects all multiple BFs that contain f/sub 1/. To enhance the applicability of CSM, test and/or design strategies for dealing with circuits that do not satisfy each rule are proposed. Such circuits include a special exclusive OR gate, BiCMOS circuits, domino logic, synchronous sequential circuits, and circuits implemented by the silicon on insulator (SOI) technology.