On removing redundancy in sequential circuits
Kwang-Ting Tim Cheng · 1991
ABSTKACT -A procedure of removing redundancy in large sequential circuits is proposed.In this procedure, no global reset state is required and no state transition information is needed.A definition of sequential redundancy is first given.We show that if a fault is pdentidy undetectubfeit is sequentially redundant.An aigorithm of identifying p-undetectable faults is then described.For large circuits, we propose a practical procedure to identify a subset, tailed feedback-free sequential redundant faults of redundant faults.In this procedure, a minimal set of signais is selected and assumed fully controllable and observable to convert the given circuit into a feedback-free model.Redundancies in the feedback-free circuit model are then identified and removed.This procedure could also eliminate redundant flip-flops.Experimental results show that our method successful y minimizes the signal count by about 8.4%, in average, on six iarge MCNC benchmark sequential circuits with up to 20K gates and 1700 flip-flops.In some examples, up to 7.8 % of the flip-flops is removed without changing the circuit's input/output behavior.