Testing Strategy and Technique for Macro-Based Circuits

The increasing complexity of VLSI systems demands structured approaches to reduce both design time and test generation effort. PLA´s and scan paths have both been widely reported to be efficient in this sense. This correspondence presents an easily testable structure and its related testing strategies. The circuits are assumed to be based on the interconnection of combinatorial macros, mostly implemented by PLA´s; tests are generated locally, considering the involved macro as an isolated item, and then are expressed in terms of primary inputs and outputs using a topological approach as general strategy and algebraic techniques for the propagation of signals through macros. Propagation is dealt with by new algorithms. Since the problem of test generation is NP-hard, a set of heuristics is introduced to keep the amount of computation reasonable; several implementation issues are finally investigated.