[SI-LIST] Re: non-negative off diagonal capacitive matrix elements ??

  • From: "Jian-X. Zheng" <jian@xxxxxxxxxx>
  • To: <Raymond.Anderson@xxxxxxx>, <si-list@xxxxxxxxxxxxx>
  • Date: Fri, 31 Aug 2001 10:16:56 -0700

Hi, Ray:

I think it is possible some off diagonal capacitances can be negative.
However, if most of them are negative, I believe it must be from numerical
error or incorrect extraction setup. In my experience, the capacitance
between adjacent lines should never be negative.

Regards,

---------------------------------------------------------------------------
Jian-X. Zheng, Ph.D.
Zeland Software, Inc., 48890 Milmont Dr. 105D, Fremont, CA 94538, U.S.A.
Tel: 510-623-7162, Fax: 510-623-7135, Web: http://www.zeland.com
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-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx
[mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of Ray Anderson
Sent: Friday, August 31, 2001 10:08 AM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] non-negative off diagonal capacitive matrix elements
??




I've just extracted the RLGC matrices for 5 coupled
striplines using Apsimtech RLGC.

As expected, the diagonal elements of the capacitive matrix are
positive capacitance values. All the off-diagonal elements are
negative EXCEPT one. Is this correct. It has been a while since I've
thought about this, but I was under the impression the capacitive
off diag element were all negative. Anyone know for sure ??

The element in column 1 row 5 is the one I question:


   3.1600e-15
  -4.9360e-16   3.2540e-15
  -2.0080e-17  -4.8990e-16   3.2540e-15
  -1.3380e-18  -1.9820e-17  -4.8990e-16   3.2540e-15
   3.1280e-20  -1.3380e-18  -2.0080e-17  -4.9360e-16   3.1600e-15




-Ray

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