Shaping a VLSI wire to minimize delay using transmission line model

Youxin Gao, D. F. Wong

Research output: Contribution to journalConference articlepeer-review


In this paper, we consider continuous wire-sizing optimization for non-uniform wires. Our objective is to find the shape function of a wire which minimizes delay. This problem has been studied recently under the Elm ore delay model. However, it is well known that Elmore delay is only a rough estimate of the actual delay and thus more accurate models should be used to determine the wire shape function. Our study uses the transmission line model which gives a very accurate estimation of the actual delay. Since previous studies under Elmore delay model suggest that exponential wire shape is effective for delay minimization, we restrict the wire shape function to be of the form f(x) = ae-bx. By solving the diffusion equation, we derive the transient response in the time domain as a function of a and b for both step and ramp input. The coefficients a and b are then determined so that the actual delay (50% delay) is minimized. Our algorithm is very efficient. In all the experiments we performed, the wire shape functions can be determined in less than 1 second.

Original languageEnglish (US)
Pages (from-to)611-616
Number of pages6
JournalIEEE/ACM International Conference on Computer-Aided Design, Digest of Technical Papers
StatePublished - 1998
Externally publishedYes
EventProceedings of the 1998 IEEE/ACM International Conference on Computer-Aided Design, ICCAD - San Jose, CA, USA
Duration: Nov 8 1998Nov 12 1998

ASJC Scopus subject areas

  • Software
  • Computer Science Applications
  • Computer Graphics and Computer-Aided Design


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