Patent ID: 7191374

Claim:
A method of fault diagnosis of an integrated circuit having failing test vectors with observed fault effects using fault candidate fault-effects obtained by simulation of a set of test vectors, comprising: determining a fault candidate diagnostic measure for each fault candidate, said fault candidate diagnostic measure having a fault candidate match metric, an observed fault effect mismatch metric and a fault candidate excitation metric; ranking fault candidates in decreasing diagnostic measure order; and identifying fault candidate(s) having the highest diagnostic measure as the most likely cause of observed fault effects, said determining a fault candidate diagnostic measure comprising, for each fault candidate: determining a match metric indicative of fault candidate fault-effects that match observed fault effects; determining a mismatch metric indicative of observed fault effects that do not match fault candidate fault-effects; and determining a fault candidate excitation metric indicative of the number failing vectors that have at least one fault candidate fault effect that matches an observed fault effect and of the number of vectors that have at least one fault candidate fault-effect.