RE: [SI-LIST] : CAD for SI, EMC. Hyperlynx experiences.

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From: Chris Rokusek (crokusek@viewlogic.com)
Date: Thu Feb 17 2000 - 14:51:55 PST


Mike,

The EMC problem is very tricky to solve both completely and efficiently with
reasonable accuracy.

There are tools that can give you a very accurate answer for a very simple
and specific case and work well for research but not practical PCBs. The
downsides are runtime, not being able to setup the tool properly (requires
Ph.D.), and not being able to test all conditions (software vectors, antenna
positions, cable position variance, pcb position within enclosure, etc!)
within a reasonable amount of time.

There are tools that perform simple FFT of T-LINE signals on surface layers
and predict differential mode only. They can only find the "long clock line
routed on surface layer" problem.

IN MY VERY BIASED OPINION, the ideal tool to have at your disposal is one
that acts as if it's an EMC consultant. These guru's can come in look at
your board, find the problem and fix it. You give them the layout, tell
them some basic information about what parts/nets do what and they can probe
around and find the "most likely suspects" on the board and tell you how to
improve them. Well, with the proper knowledge base built in, a CAD tool can
do a more-thorough job in a fraction of the time. This effective EMC
Software "Expert System" estimates Common-Mode, Diff-Mode and performs
"Screening" based on extensible rules just as an EMC consultant would do.

Chris Rokusek
Viewlogic Systems

> -----Original Message-----
> From: owner-si-list@silab.eng.sun.com
> [mailto:owner-si-list@silab.eng.sun.com]On Behalf Of Mayer, Mike
> Sent: Thursday, February 17, 2000 1:35 PM
> To: 'si-list@silab.eng.sun.com'
> Subject: RE: [SI-LIST] : CAD for SI, EMC. Hyperlynx experiences.
>
>
> > My main objective is to reduce the number of PCB iterations
> > and off-site testing, by predicting the EM radiation from a
> > PC board, and be able to compare different ground plane and
> > signal routing strategies.
>
> I have no direct experience with EMC tools, but as far as I know they are
> not very good at predicting emissions caused by common mode currents.
>
> I do have direct experience with EMC testing, and most emissions
> problems I
> have had are with common mode currents on cables.
>
> ==================================================================
> ==========
> =
> Mike Mayer Artesyn Communication
> Products, Inc
> Senior Hardware Design Engineer Madison, WI
> Mike.Mayer@cp.artesyn.com http://www.artesyn.com/cp
> ==================================================================
> ==========
> =
>
>
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