Fast Test Generation for Structurally Similar Circuits

This paper describes a fast test generation process for digital circuits that exhibit extensive structural similarity. The property of structural similarity can be seen in circuits that are subjected to engineering change order (ECO), circuits that are modified during place and route, circuits subjected to retiming, and circuits with multiple similar cores. The goal of the paper is to determine the testability of a circuit (circuit2) given a test set for a structurally similar circuit (circuit1). This is achieved by transforming a test set generated for circuit1 into a test set for circuit2 as efficiently as possible, without repeating the entire test generation process. The process described in the paper starts with a structural analysis of circuit1 and circuit2 to obtain a mapping between their inputs and outputs. The mapping is used for transforming test patterns from circuit1 into test patterns for circuit2. The experiments conducted on industrial designs show an average of more than 10-fold reduction in runtime, compared with running the entire test generation process for circuit2.