Standard cell placement using simulated sintering

  • Authors:
  • L. K. Grover

  • Affiliations:
  • AT&T Bell Laboratories, Murray Hill, New Jersey

  • Venue:
  • DAC '87 Proceedings of the 24th ACM/IEEE Design Automation Conference
  • Year:
  • 1987

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Abstract

Simulated annealing is a powerful optimization technique based on the annealing phenomenon in crystallization. In this paper we propose a simulated sintering technique which is analogous to the sintering process in material processing. In sintering one improves the quality of a processed material by heating it to a temperature close to the melting point. Analogously, we show that by starting out with a good initial configuration instead of a random configuration, and restricting uphill moves, we can considerably speed up simulated annealing. We use this idea for a standard cell placement program - GRIM in LTX2, an AT&T Bell Labs VLSI layout system. The initial configuration is produced either by changes to a layout the designer had done previously, or else by a fast program like min-cut. We obtain improvements of about 10% in chip area starting from a min-cut placement, in times about 3 times faster than our simulated annealing program (which itself is several times faster than other well known simulated annealing programs).