Fault Modelling with Structural BDDs

In this chapter, we propose methods for modelling faults in structural Binary Decision Diagrams (BDDs). We show how to map the nodes in different structural BDDs, such as SSBDDs and S3BDD to signal paths or path segments in the gate-level circuits, and how they can represent the Stuck-At Fault (SAF) locations. A method is presented for extending the SAF to the conditional SAF model for detecting physical defects, and a method is developed for formal calculation of the conditions related to defects. We present novel ideas of formal fault collapsing by applying the fault equivalence and dominance relationships using the formalism of structural decision diagrams. To reduce the size of the SAF model, we propose a fault-collapsing method with linear complexity.