A satisfiability-based test generator for path delay faults in combinational circuits

The paper describes a new formulation to generate robust tests for path delay faults in combinational circuits based on Boolean satisfiability. Conditions to detect a target path delay fault are represented by a Boolean formula. Unlike the technique described by A. Saldhana et al. (1992), which extracts the formula for each path delay fault, the proposed formulation needs to extract the formula only once for each circuit cone. Experimental results show tremendous time saving on formula extraction compared to other satisfiability based ATPG algorithms. This also leads to low test generation time, especially for circuits that have many paths but few outputs. The proposed formulation has also been modified to generate other types of tests for path delay faults.