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VLSI Design
Volume 5 (1996), Issue 1, Pages 23-36

A Greedy Algorithm for Over-The-Cell Channel Routing

1Sunnuhvoli B, IS-170 Seltjarnarnes Iceland, USA
2Computer Science Program, The University of Texas at Dallas, Richardson 75083-0688, TX, USA

Received 19 September 1994; Accepted 20 June 1995

Copyright © 1996 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.


Recent advances in VLSI technology have made the area over cells available for routing. In this paper we present a new over-the-cell channel router that uses greedy heuristics to make the over-the-cell connections and to define the nets needed to complete the connections inside the channel. The router tries to reduce the channel density by moving segments that cross maximum density columns to the over-the-cell areas. The layout model used allows only planar connections over each cell. The final stage is to use an existing channel router to route the connections inside the channel. An important characteristic of the new router is that there is interaction between the decisions made for the over-the-cell connections and the connections needed inside the channel. It performs significantly better than previous over the-cell routers.