Clock Period Minimization of Semi-Synchronous Circuits by Gate-Level Delay Insertion

Tomoyuki YODA  Atsushi TAKAHASHI  

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E82-A   No.11   pp.2383-2389
Publication Date: 1999/11/25
Online ISSN: 
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on VLSI Design and CAD Algorithms)
delay insertion,  clock period minimization,  semi-synchronous circuit,  

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A semi-synchronous circuit is a circuit in which every register is ticked by a clock periodically, but not necessarily simultaneously. In a semi-synchronous circuit, the minimum delay between registers may be critical with respect to the clock period of the circuit, while it does not affect the clock period of an ordinary synchronous circuit. In this paper, we discuss a delay insertion method which makes such a semi-synchronous circuit faster. The maximum delay-to-register ratio over the cycles in the circuit gives a lower bound of the clock period. We show that this bound is achieved in the semi-synchronous framework by the proposing gate-level delay insertion method.