On the diagnostic resolution of signature analysis

An examination was made of the diagnostic properties of signature analysis. By theoretical and experimental studies the authors derived the probabilities that a given number of signatures occur during a test, and that a given number of signatures will be produced uniquely (i.e. by one fault). These characteristics were validated by a series of simulations of the benchmark circuits under test together with a response compaction procedure using linear feedback shift registers (LFSRs) implementing primitive polynomials. The experimental results confirm the validity of the theoretical model. The authors perform further calculations in order to reveal some important relationships between the size of the used LFSR, the total number of faults and the diagnostic resolution of signature analysis. Indeed, these results provide justification for the adoption of a simple formula that encompasses all the factors considered in the signature analysis compaction technique. Because of its simplicity it can be used directly in VLSI BIST design as well as in a wide range of other applications.<>