[SI-LIST] Re: Decoupling capacitors
- From: "Heiko Dudek" <heikod@xxxxxxxxxxx>
- To: <Raymond.Anderson@xxxxxxx>, <si-list@xxxxxxxxxxxxx>
- Date: Wed, 29 May 2002 18:10:17 +0200
Ray,
1x1, 2x2, 4x4, 8x8 and 16x16 are only suggestions ... you can enter
anything you want (just type it in, don't pick a selection from the
pull-down menu).
- Heiko
-----Original Message-----
From: Ray Anderson [mailto:Raymond.Anderson@xxxxxxx]
Sent: Dienstag, 28. Mai 2002 18:55
To: si-list@xxxxxxxxxxxxx
Cc: arpad.muranyi@xxxxxxxxx
Subject: [SI-LIST] Re: Decoupling capacitors
Arpad-
I think you are probably correct. I really hadn't looked at
the meshing selections in the sqpi preferences menu for quite a while.
I believe in a very early pre-release version sqpi had the ability=20
to select meshing up to 32x32 (or something like that), but the
execution time was so long that apparently they opted to limit
the available size to 16x16 in the released version. Currently
the selections are 1x1, 2x2, 4x4, 8x8, and 16x16. I kind of wonder
what practical use the 1x1 and 2x2 (and even 4x4) meshing serves.
Meshing that coarse will limit the accuracy of the simulation to
very low frequencies (but it sure will simulate fast...).
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.
So to re-answer the the original question, 16x16 meshing is more than
adequate for most real world problems if one realizes that the selection =
of
a mesh size is a tradeoff of accuracy vs time. Most of our simulations =
are
done with 8x8 meshing which provides good accuracy at "SI" frequencies
(i.e. < say ~600 MHz or so depending on the board size), but introduces=20
some error at higher frequencies. At one point in time I built a simple=20
test board consisting of just a couple planes and measured the impedance =
profile in the lab with a VNA. Then I simulated the same board (about 4" =
x 6")=20
using the plane model with 8x8 meshing. I found real good measurement to =
simulation correlation up to about 1.3 GHz from which point on there was
increasing divergence between the measured and simulated data.
Referencing back to my fouled-up numerical example of yesterday,
with 16x16 meshing, accuracy should be fine up to 1 GHz on a
board of about 240mm x 240 mm size. (1/10 lambda @ 1GHz ~ 15mm
on FR-4, so 16 x 15 mm =3D 240 mm). (thanks to Scott for pointing out=20
my metric unit errors yesterday:)
-Ray
>
>Ray,
>
>I think he was asking you whether SQPI's maximum mesh
>density (16x16) is good enough...
>
>Arpad
>=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D
>
>
>
>
>>sogo_hsu wrote:
>>.
>> ..... text deleted....
>>
>> Besides, don't you think the mesh density in 16 by 16 is too rough to
>> analyze a real PDS plane in SQPI?
>>=20
>> Sogo
------------------------------------------------------------------
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: =20
//www.freelists.org/archives/si-list
or at our remote archives:
http://groups.yahoo.com/group/si-list/messages=20
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
=20
------------------------------------------------------------------
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:
