[SI-LIST] Re: non-negative off diagonal capacitive matrix elements ??
- From: "Jian-X. Zheng" <jian@xxxxxxxxxx>
- To: <xlzhou@xxxxxxxxx>, <Raymond.Anderson@xxxxxxx>,<si-list@xxxxxxxxxxxxx>
- Date: Fri, 31 Aug 2001 10:51:17 -0700
Hi, Nick:
If you use static solver to solve for the capacitance matrix, you should get
non-negative capacitance. If they are not, it should be caused by error
(numerical or analytical).
However, you can not guarantee it if you are using full wave solvers. It is
not the problem of the accuracy in full wave solvers. On full-wave solvers,
extraction of the capacitance matrix is basically matching. The solvers can
predict negative off diagonal capacitances because they may represent the
trend of the system responses better in a specific frequency range. Thanks!
Best 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 Zhou, Xingling
(Xingling)
Sent: Friday, August 31, 2001 10:39 AM
To: 'jian@xxxxxxxxxx'; Raymond.Anderson@xxxxxxx; si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: non-negative off diagonal capacitive matrix
elements ??
Hi, Zheng
I think you are talking about another definition which is good for SPICE
simulations. But for fied solvers, it is
better to use Maxwell's definition. We can find the details in any
multi-conductor books. There is a clear description
in Brian Young's book, pp.233-235.
Regards.
Mick
-----Original Message-----
From: Jian-X. Zheng [mailto:jian@xxxxxxxxxx]
Sent: Friday, August 31, 2001 1:17 PM
To: Raymond.Anderson@xxxxxxx; si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: non-negative off diagonal capacitive matrix
elements ??
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
---------------------------------------------------------------------------
-----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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