Robust Fault Models Where Undetectable Faults Imply Logic Redundancy

We define a robust fault model as a model where the existence of an undetectable fault implies the existence of logic redundancy. The stuck-at fault model is robust, but other fault models such as certain bridging and interconnect open fault models are not. A robust fault model provides a mechanism to synthesize circuits in which all the target faults are detectable and 100% fault coverage is achievable. This is important since it provides a direct link between test quality and the circuit synthesis. We discuss robust fault models for bridging faults and interconnect open faults, and their use as part of a test generation process for a non-robust fault model.