Schedule-Clock-Tree Routing for Semi-Synchronous Circuits

Kazunori INOUE  Wataru TAKAHASHI  Atsushi TAKAHASHI  Yoji KAJITANI  

Publication
IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E82-A   No.11   pp.2431-2439
Publication Date: 1999/11/25
Online ISSN: 
DOI: 
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on VLSI Design and CAD Algorithms)
Category: 
Keyword: 
clock-tree,  clock-scheduling,  semi-synchronous circuit,  deferred-merge embedding,  

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Summary: 
It is known that the clock-period can be shorter than the maximum of signal-delays between registers if the clock arrival time to each register is properly scheduled. The algorithm to design an optimal clock-schedule was given. In this paper, we propose a clock-tree routing algorithm that realizes a given clock-schedule using the Elmore-delay model. Following the deferred-merge-embedding (DME) framework, the algorithm generates a topology of the clock-tree and simultaneously determines the locations and sizes of intermediate buffers. The experimental results showed that this method constructs a clock-tree with moderate wire length for a random layout of scheduled registers. Notably, the required wire length for a gentle layout of scheduled registers was shown to be almost equal to that of zero-skew clock-trees.