A timing-constrained simultaneous global routing algorithm

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21 Scopus citations


Proposed in this paper is a new approach for VLSI interconnect global routing that can optimize both congestion and delay, which are often competing objectives. The authors' approach provides a general framework that may use any single-net routing algorithm and any delay model in global routing. It is based on the observation that there are several routing topology flexibilities that can be exploited for congestion reduction under timing constraints. These flexibilities are expressed through the concepts of a soft edge and a slideable Steiner node. Starting with an initial solution where timing-driven routing is performed on each net without regard to congestion constraints, this algorithm hierarchically bisects a routing region and assigns soft edges to the cell boundaries along the bisector line. The assignment is achieved through a network flow formulation so that the amount of timing slack used to reduce congestions is adaptive to the congestion distributions. Finally, a timing-constrained rip-up-and-reroute process is performed to alleviate the residual congestions. Experimental results on benchmark circuits are quite promising and the run time is between 0.02 s and 0.15 s per two-pin net.

Original languageEnglish (US)
Pages (from-to)1025-1036
Number of pages12
JournalIEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems
Issue number9
StatePublished - Sep 2002

Bibliographical note

Funding Information:
Manuscript received December 18, 2000; revised September 7, 2001 and January 21, 2002. This work was supported in part by the National Science Foundation under Contract CCR-9800992 and by the SRC under Contract 98-DJ-609. This paper was recommended by Associate Editor M. Pedram.


  • Global routing
  • Interconnect
  • Layout
  • Performance optimization
  • Physical design
  • VLSI


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