Design for Testability Using State Distances

The average distance between states is proposed as a new testabilitymeasure for finite state machines (FSMs). Also proposed is theconcept of center state to reduce distances in FSMs. This testfunction embedding technique has been shown to improve thetestability of sequential circuits with minimal overhead. Anoverview of several design-for-testability (DFT) andsynthesis-for-testability (SFT) methods for sequential circuits willalso be given in this paper. Experimental results have shown thatthe DFT approach is more advantageous than the SFT approach toimplement our test function. The contribution of this paper is toanalyze the trade-offs between several aspects of DFT and SFTtechniques.