[SI-LIST] Re: ADS usage in SI analysis

Guys,
Don't get me wrong. I am a big fan of ADS and always willing to stand up =
and defend why I think ADS is a good tool and suits my work well.
But there is an old Chinese saying, "don't try to kill a chicken with a =
cow sword". I am still trying to understand why the original application =
in question needs such a tool. Too many times I hear this "my latest and =
greatest 3D FDTD full wave tool is awesome because I need it to model a =
via on my PC board so that I can design my 50MHz/PCI/DDR bus". I can =
name a few reasons why one will need a full wave FDTD tool and I can =
name a few hundred reasons why you don't need one. I really don't want =
to recommend anything unless there is a need for it. Does it make sense =
?
Chris

 -----Original Message-----
From:   Gary Otonari [mailto:garyo@xxxxxxxxxxxx]=20
Sent:   Tuesday, August 23, 2005 10:55 AM
To:     fzanella@xxxxxxxxxxxxx; Andrew.Burnside@xxxxxxxxxxxxxxxxxxx; Chris =
Cheng; 'List` Si'
Subject:        RE: [SI-LIST] Re: ADS usage in SI analysis

Agree with most that has been posted regarding ADS, Momentum and CST.  =
One
more point.  ADS has a 2D "static" solver which is used by the =
"Multilayer
Line Library" components.  This has been a useful tool here at GigaTest =
for
many reasons:

1.  It is flexible, allowing lots of structures/ stackups to be modeled. =
 We
have used it for package substrates, PCBs, even connectors and cables.

2.  It's accurate. We use these models routinely to model structures to =
10
GHz, less frequently, to 20 GHz and higher.  These are =
measurement-verified.

3.  It's fast.  Because the 2D solver is written for the specific
structures/ stackups in the Multilayer Line library, it is very fast
compared with other field solvers (like Momentum)

4.  It will output a frequency dependent RLGC file, which can be =
translated
into a W-element compatible file for use in HSPICE

-- Gary

-------------------------------------------------------------------------=
---
--------
Attend the GTL Signal Integrity University in Sunnyvale, CA  -  August =
22 -
25=20
=20
GTL 122 - Fundamental Principles of Signal Integrity
GTL 250 - High Speed Board Design
=20
GigaTest Labs   =20
134 South Wolfe Road   *   Sunnyvale,  CA    *     94086
408.524.2700
www.gigatest.com
=20

-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] =
On
Behalf Of Zanella, Fabrizio
Sent: Tuesday, August 23, 2005 10:00 AM
To: Andrew.Burnside@xxxxxxxxxxxxxxxxxxx; Chris.Cheng@xxxxxxxxxxxx; List` =
Si
Subject: [SI-LIST] Re: ADS usage in SI analysis

ADS provides co-simulation with the CST Microwave Studio 3D solver.
This is a better alternative than Momentum for accurate modeling of
packages and other structures.
Regards, Fabrizio

-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
On Behalf Of Andrew Burnside
Sent: Saturday, August 20, 2005 5:09 AM
To: Chris.Cheng@xxxxxxxxxxxx; List` Si
Subject: [SI-LIST] Re: ADS usage in SI analysis

Having used ADS momentum quite a bit for board SI/microwave design, I
wouldn't necessarily agree that it is the best program for package SI.
Yes, you can create packages by adding multiple layers, but the user
interface is in essence 2D, with some limited 3D features.=3D20

The momentum solver, as the name suggests uses the Method of Moments.
This is not as accurate as 3D solvers such as HFSS. In addition, the
Momentum RF mode can give you Quasi-static calculations, slighly less
accurate but a lot faster run times. The accuracy all depends on what
kind of shapes you are trying to simulate.

Regards

Andrew


-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx on behalf of Chris Cheng
Sent: Sat 20/08/2005 07:57
To: List` Si
Subject: [SI-LIST] Re: ADS usage in SI analysis
=3D20
It's no secret I am a big fan of ADS.
I believe it is the closest complete package for highspeed SI design one
can wish.
=3D20
That said, if you are strictly using ADS momentum as a package SI
analysis and nothing else, it may be more cost effective to use a free
tool such as FastHenry/FastCap or more specialized tool like Sigrity. I
think momentum is more like a simplified subset of HFSS that tries to
address a lot of common field solving models I encounter. However, I
seem to be able to break it in every turn I make. The via model simply
doesn't work. I've found the problem since last year and Agilent is well
aware of that.=3D20
=3D20
Will that stop me from using or recommending ADS ? Absolutely not.
Because it is never meant to be a specialized tool for package SI
analysis only. It's tight integration of a SPICE engine to S-parameter
models together with schematics frontend and the limited but sufficient
momentum field solver is all I need for highspeed SI design. The ptolemy
extension is more useful for me than those xxxxAMS.
=3D20
That's my own experience, YMMV.=3D20
=3D20
May be share with us what kind of package SI analysis you really want to
do ? Core power distribution ? SSO models ? Speed limit  @ DDR  Gb
serdes ? Different strokes for different folks.
________________________________

From: si-list-bounce@xxxxxxxxxxxxx on behalf of Bi Han
Sent: Fri 8/19/2005 9:21 PM
To: List` Si
Subject: [SI-LIST] ADS usage in SI analysis



HI, folks:

I am interested to know that how many companies are using ADS momentum
solver as major tool in package SI analysis.

Any one is willing to share me your feeling on this tool's accuracy and
speed?

thanks,
Han


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