[SI-LIST] Re: Decoupling capacitors - mesh density
- From: "Raj Raghuram" <raghu@xxxxxxxxxxx>
- To: <si-list@xxxxxxxxxxxxx>
- Date: Tue, 28 May 2002 17:12:20 -0700
Sogo, Ray,
The limiting constraint for the number of meshes is usually the spatial
resolution instead of the one-tenth wavelength criterion. The planes are
typically of complex shapes with multiple patches and voids. Moreover, there
can be a large number of via connections between the planes. In order to
adequately represent the geometry, the vias connected between planes, and
components (such as decaps) mounted on the board, it is often necessary to
use a few hundred meshes to the side even for small boards or packages.
The simulation times for HSPICE are unusually high because HSPICE was not
designed to solve such circuits containing transmission line meshes.
Therefore, special solvers are needed for such applications. By way of
comparison, using our special solver (PowerSI) we were able to solve a
208x208 transmission line mesh plane model in about 14 seconds. In 23
minutes, we were able to compute 100 frequency points. Loading time is
negligible. The data was obtained on a Pentium III 866 PC with Windows 2000
OS.
Best Regards,
Raj Raghuram
Sigrity, Inc.
"Achieve what others can't"
raghu@xxxxxxxxxxx
http://www.sigrity.com
4675 Stevens Creek Blvd. , Ste 130
Santa Clara, CA-95051
PH: 408-260-9344 x116
CELL: 408-390-7614
FAX: 408-260-9342
> -----Original Message-----
> From: si-list-bounce@xxxxxxxxxxxxx
> [mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of Ray Anderson
> Sent: Tuesday, May 28, 2002 3:25 PM
> To: si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] Re: Decoupling capacitors
>
>
>
>
> In an earlier message I wrote:
>
> >I have written some simple C code that can generate plane models
> >equivalent to the ones in sqpi for use with hspice with any arbritrary
> >meshing. Models with very dense meshing can be very expensive in
> >terms of compute time.
>
>
> As an experiment I generated a 208x208 mesh plane model. Just
> to read it into Hspice (2001.2) without even doing any simulation
> at all took 1398 seconds ( ~23 minutes) on a 440 MHz Ultra-10
> workstation. Had this model been used for a simulation it would
> have been able to simulate a board 10ft 3in square accurately to
> 1 GHz (or a much smaller board to a much higher frequency).
>
> What's it prove? Not much except to point out that very large
> models consume lots of computer resources, and that users need
> to make intelligent choices on how detailed of a model makes
> sense for any particular application......
>
>
>
> -Ray Anderson
> Sun Microsystems Inc.
>
>
> ------------------------------------------------------------------
> To unsubscribe from si-list:
> si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
>
> or to administer your membership from a web page, go to:
> //www.freelists.org/webpage/si-list
>
> For help:
> si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
>
> List archives are viewable at:
> //www.freelists.org/archives/si-list
> or at our remote archives:
> http://groups.yahoo.com/group/si-list/messages
> Old (prior to June 6, 2001) list archives are viewable at:
> http://www.qsl.net/wb6tpu
>
>
>
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List archives are viewable at:
//www.freelists.org/archives/si-list
or at our remote archives:
http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
Other related posts:
