Xref: utzoo comp.lsi:461 sci.electronics:2930
Path: utzoo!mnetor!uunet!lll-winken!lll-lcc!pyramid!decwrl!stark
From: stark@decwrl.dec.com (Don Stark)
Newsgroups: comp.lsi,sci.electronics
Subject: Re: (In)correct Parasitic Extraction
Message-ID: <435@bacchus.DEC.COM>
Date: 10 May 88 04:18:42 GMT
References: <2151@obiwan.mips.COM>
Organization: Digital Equipment Corporation
Lines: 22
Keywords: LPE  fringing-capacitance  MOS
Summary: Take a look at magic

In article <2151@obiwan.mips.COM> mark@mips.COM (Mark G. Johnson) writes:
>
>Why?  We need to distinguish between a poly edge and a metal-2 edge,
>but the L.P.E. software can't tell them apart.
>
Magic does what you're looking for.  Instead of finding the intersection 
between metal2 and polysilicon, it looks at each polysilicon/space edge, and 
sees if it overlaps metal2. If it does, a poly-edge-over-metal2 cap is added.
Metal2-space edges are likewise checked to see if they are over polysilicon; 
if so, a metal2-edge-over-poly cap is added.

This is fast and easy to do in a tiled database, but considerably more 
difficult if you're just sorting polygons and finding their intersection.

I think Walter Scott's paper on the circuit extractor contains more details:

Walter S. Scott and John K. Ousterhout, "Magic's Circuit Extractor", 
Proceedings of the 22nd Design Automation Conference, 1985, 286-292.


Don Stark
Stanford University
stark@bill-the-cat.stanford.edu