Design replacements for sequential circuits
Vigyan Singhal, Robert K. Brayton · 1996
In this dissertation we study the problem of design replacements for synchronous sequential circuits. There have been previous efforts to characterize the criterion for replacement for such circuits. However, all previous attempts either make implicit or explicit assumptions about the design or the environment of the design (for example, all latches have a hardware reset line and the design operation starts in a unique designated initial state). We present a notion for replacement which works for any arbitrary environment, and without making these assumptions. We also observe that if the design's output is not used for a certain number of cycles after power-up then allows additional flexibility is available for replacement. We have used these notions of design replacement for logic optimization and we report encouraging results. We also prove the complexity of the verification problem for these notions as well as heuristics for this this problem.