Table of Contents
VLSI Design
Volume 2, Issue 3, Pages 241-257

SEGMA: A Simulated Evolution Gate-Matrix Layout Algorithm

Department of Electrical and Computer Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA

Received 3 December 1992; Revised 17 March 1993

Copyright © 1994 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


In this paper, we present a Simulated Evolution Gate Matrix layout Algorithm (SEGMA) for synthesizing CMOS random logic modules. The gate-matrix layout problem is solved as a one-dimensional transistor gates placement problem. Given a placement of all the transistor gates, simulated evolution offers a systematic method to improve the quality of the layout that is measured by the number of tracks needed for the given netlist. This is accomplished by identifying a subset of gates whose relative placements are deemed “poor quality” according to a heuristic criterion. By rearranging the placement of these identified subsets of gates, it is hoped that a gate placement with better quality, meaning fewer tracks, may emerge. Since this method enables the current “generation” of gate placement to evolve into a more advanced one in a way similar to the biological evolution process, this method is called simulated evolution. To apply simulated evolution to solve the gate-matrix layout problem, we propose a novel heuristic criterion, called randomized quality factor, which facilitates the judicious selection of the subset of poor quality gates. Several carefully devised and tested strategies are also implemented. Extensive simulation results indicate that SEGMA is producing very compact gate-matrix layouts.