FreeLists / si-list / [SI-LIST] Re: EMI simulation tools at PCB level

[Julian Ferry <julian.ferry@xxxxxxxxxx>]

I concur with Ron on the effectiveness of the FLO/EMC software. We use the
Microstripes portion. Its been a while since I looked into Flomerics
packaging, but I think Microstripes is part of the FLO/EMC group.  I'm not
saying that its better or worse than anything else available. What I am
saying is that it is a tool we use regularly, and it works great for us. 

Learning how to get the right info from the software for our particular
situation was a long, painful process. I know that can be said about most
any engineering tool, but be prepared for something longer and more painful
than you might expect.  But now that we are over that hump, I don't know how
we could get along with out it (or a similar tool) now.  We keep two seats
running practically 24/7/52. 

We have analyzed PCBs, connectors (shielded and unshielded), and cable
assemblies with connectors attached.  In radiation simulations, we have
gotten 1 or 2 dB correlation with lab measurements. Its important to note
that this is a relative correlation. So it's a great tool for doing what-if
type comparative analysis. I can't vouch for pass/fail type analyses.

Some caveats in addition to Ron's:

1) The software is expensive, and not just in the up front dollar cost. The
learning curve is steep (measured in months), and its not something you are
going to do in your spare time. It is also very much a "use it or lose it"
kind of experience. If you don't use it regularly, it can be frustrating and
not even worth the effort.  Consultants really are a good way to go
initially.

2) Run times can be in the weeks.  If you've got real parts available, it
can be faster and cheaper to just go to the lab and measure.

3) We needed to develop some custom post processing procedures to get the
exact kind of data we were looking for. That took some more time and effort.

Some plusses:

1) Once you have made the initial investment in dollars and time, and have
developed a good modeling process, you can save many dollars and much time
versus building prototypes and testing them.

2) The field visualization and animation capabilities can highlight problem
areas very quickly. They also can be a big help in developing an intuitive
feeling for what is happening.  But plan on adding another couple days or
weeks to your run times if you want that info.....

3) With proper set up, one solver run can give you more than just EMC
information. We also get SI info like crosstalk, impedance profiles,
S-parameters, etc. In realty, we use the tool for obtaining SI info much
more often than for EMC info.

Bottom line, its a great tool, but it takes time, effort, and dedication to
learn to use it properly. 


Julian Ferry
High Speed Engineering Manager
Samtec, Inc.
   

 

-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
Behalf Of Ron Matthews
Sent: Friday, December 03, 2004 10:20 AM
To: rsefton@xxxxxxxxxxxxx; Chris.Cheng@xxxxxxxxxxxx; si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: EMI simulation tools at PCB level

I've used FLO/EMC extensively and I can tell you that it's very accurate 
and is a good solution for doing a serious EM evaluation of a PCB. You can 
also evaluate the PCB within a chassis with or without cables. That's the 
good news. The caveat here is that FLO/EMC is a full-wave 3D field solver. 
As such, there is quite a bit of setup and possible translation of board 
files involved if you are going to get meaningful results. Further, the 
user really has to know the right questions to ask when using a tool of 
this type. This is definitely not a tool where one can simply create a 
model, kick off the field solver to solve the entire domain and expect to 
come away knowing if their system is going to pass EMI testing. However, if 
the user has a fair idea of the EMI-related risks their system is likely to 
present, those risks can be effectively evaluated and meaningful results 
can be obtained.

Regards,

Ron Matthews
Principal MTS
Signal Integrity/EMI
Charles Stark Draper Laboratory
555 Technology Square
Cambridge, MA 02139
Voice: 617-258-2519

At 06:56 AM 12/3/2004 -0800, Robert Sefton wrote:
>Chris Cheng wrote:
> > You mean the =22 part ? :-D
> >
> > Seriously, I know it is understandable and explainable but I want it
> > to be automatically predicted and simulated by a tool. It is easy to
> > fix and patch after the fact but I have yet to see a tool to tell me
> > ahead of time the db and peaks location. A bare PCB with a few
> > "experimental traces" as in some EMI papers, sure. A multi-boards
> > system with chassis and spaghetti cables come out ? Show me the
> > money.
> >
>
>Chris -
>
>I've never used the software and don't know the details of it (i.e., I'm
>just aware that it exists), but take a look at FLO/EMC from Flomerics. They
>claim to do pretty much exactly what you describe.
>
>http://www.flomerics.com/
>
>Regards,
>Bob Sefton
>
>
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