Hierarchical specification-driven analog fault modeling for efficient fault simulation and diagnosis

In this paper we discuss the capabilities of the MiST PROFIT (Mixed Signal Test Program for Fault Insertion and Testing) software for hierarchical fault modeling, tolerance modeling, fault clustering and fault diagnosis of complex mixed-signal systems. The software is designed to exploit the relationships between high level system specifications and module-level faults in complex and nonlinear mixed signal systems. Hierarchical simulation based methods are used to capture fault effects at different levels of circuit abstraction. The key features of our approach are: (a) the ability to compute tolerance effects from nonlinear behavioral models at different levels of circuit design hierarchy accurately using low-cost simulation based methods, (b) the ability to perform compaction of fault effects while transferring fault effects from the leaf cells to the highest level behavioral models, (c) the ability to capture parametric (soft) failure effects over the entire anticipated range of faulty parameter values and (d) the ability to construct fault dictionaries given a set of least replaceable units to diagnose.