[SI-LIST] Re: How good are tools to predict Radiated Emissions ?

Silqun:

It was already asked in reply to the guy talking about the mentor tools, but
where do you get your device models? How good are they? Is your tool also
doing ground/power noise, taking into account common mode noise that gets
out on cables, etc. Yes, it can do a lot if you have good models and put
them in correctly. You don't just push a button. The setup and model
collection/setup is a major time investment. I suspect the price for both
SIWAVE and HFSS, which together have a huge learning curve, is also huge.
The tools like Quiet Expert are good when you need to debug something and to
predict dangerous combinations of harmonics but will not give you the proper
emissions spectrum (in dB) for a board in a package and seldom agree for no
package if you have lots of buried lines. They are good at calculating
magnetic field emissions only for tracks on the primary/secondary sides. The
rules based tools are probably better if a an EMC engineer gets to tweak
them. This way you layout the board to avoid EMC problems. FloEMC at least
passes the IEEE test cases for EMC and has an easy to use UI when designing
packaging to meet a certain shielding budget.

It all comes down to what you need the tool for, are you trained in the tool
and in properly applying it, and what kind of budget and design flow you
have? The most ROI is in a predictive tool and in applying sound design
principles so that you pass the EMC tests on the first board/packaging spin.
Nothing beats a trained EMC engineer working with his brain, experience, and
whatever tools he has available. The most cost is when you need a diagnostic
tool to determine why you failed because you then need to respin the board
or packaging.

No disrespect to pure board designers/packaging engineers but you really
need an EMC person working with you on the design. Some designs are easy and
require little input from the EMC person and some are really tough requiring
a lot of effort from the EMC person. The EMC person can recognize what tools
he needs for the job. Every company should have 1 or more EMC people spread
over several design groups.

Cheers,

-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx
[mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of Silqun Leung
Sent: Sunday, May 28, 2006 9:31 PM
To: kalevi@xxxxxxxxxx; weirsi@xxxxxxxxxx; Shiraz.Bashir@xxxxxx; SI-List
Subject: [SI-LIST] Re: How good are tools to predict Radiated Emissions
?


Actually, there is something.  For the complex board one can use Ansoft
SIwave to compute the radiated far and near fields.  If you want to
place this board into a housing/enclosure, this near or far field
solution can be passed via co-simulation to HFSS for the 3D analysis.

Regards,
Silqun

-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
On Behalf Of Kai Keskinen
Sent: Saturday, May 27, 2006 7:31 PM
To: weirsi@xxxxxxxxxx; Shiraz.Bashir@xxxxxx; SI-List
Subject: [SI-LIST] Re: How good are tools to predict Radiated Emissions
?

FloEMC passes the IEEE test cases for radiated emissions. It is intended
to model the effects of packaging and takes into account things such as
slots, cavities, EMI gaskets with lower conductivity than metal etc. It
is helpful in creating packaging with high shielding effectiveness. None
of the tools let you take a complex board, stick it into a package or
housing, and then push a button to predict far field emissions.



-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx
[mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of steve weir
Sent: Friday, May 26, 2006 12:57 PM
To: Shiraz.Bashir@xxxxxx; SI-List
Subject: [SI-LIST] Re: How good are tools to predict Radiated Emissions
?


There has been much disappointment in this area.  Tools can show
relative noise sources.  Absolute accuracy seems poor.
Steve.
At 09:48 AM 5/26/2006, Bashir, Shiraz \(GE Healthcare\) wrote:
>How good are tools to predict Radiated Emissions ?
>
>I mean..we can layout a board using some flow. Then use a tool to see=20
>how this design will do from Radiated Emissions perspective..
>Did anyone of you have experience in this area ?
>
>Are there any tools which can pull in products' packaging (mechanical=20
>housing/ plastics, connectors location, length of slots etc..) and take

>into account for analysis for Radiated Emissions..
>
>Reason I am asking is that most of the company I know including mine=20
>heavily rely on actual testing in-house (3 meter chambers) and outside=20
>(10 Meters) which is risky..
>Because project is near completion and any tweaks cost big $s.
>
>Please let me know.
>Shiraz Bashir
>GE Healthcare
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