[SI-LIST] Re: EMI simulation tools at PCB level

Chris,
I too have used HyperLynx for EMI simulation.  However, for one it does 
not simulate differential lines.  Also, the calculated emissions are only 
differential-mode, whereas we know that almost all the EMI problems are 
associated with common-mode emissions.  Hence, while one can get some idea 
of the emission profile for different topology, it has little relevance to 
the actual emissions one is likely to see in real life.

Regards, Ravinder
Server PCB Development
Hitachi Global Storage Technologies

Email: Ravinder.Ajmani@xxxxxxxxxxxxxx




"Chris McGrath" <chris.mcgrath@xxxxxxxx>
Sent by: si-list-bounce@xxxxxxxxxxxxx
12/03/2004 06:35 AM
Please respond to chris.mcgrath

 
        To:     <si-list@xxxxxxxxxxxxx>
        cc: 
        From:   si-list-bounce@xxxxxxxxxxxxx
        Subject:        [SI-LIST] Re: EMI simulation tools at PCB level




On the whole, I agree with Ron but wanted to add (feel free to disagree)
that I have found it useful to do comparisons of EMI performance within
Hyperlynx between different circuit topologies of on-board interfaces.
For instance, trying an SDRAM interface both with and without parallel
termination yielded quite different results and that helped build a case
for our approach to the design.  In that capacity, I think that the EMC
tool in that simulator can be useful.

-Chris


> -----Original Message-----
> From: si-list-bounce@xxxxxxxxxxxxx=20
> [mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of Ron Matthews
> Sent: Friday, December 03, 2004 9:06 AM
> To: Chris.Cheng@xxxxxxxxxxxx; 'Charles Grasso '; Chris Cheng;=20
> 'zhang_kun@xxxxxxxxxx '; 'si-list@xxxxxxxxxxxxx '
> Subject: [SI-LIST] Re: EMI simulation tools at PCB level
>=20
>=20
> Chris,
>=20
>          This is one of those areas where you'll probably=20
> never be able to=20
> remove the human from the simulation in order to get=20
> meaningful results.=20
> Since the radiated emissions profile of a PCB is heavily=20
> dependent on the=20
> immediate operational environment (i.e. the enclosure, cable,=20
> etc.) it's=20
> not really meaningful to have a program automatically predict=20
> what the EMI=20
> levels are going to be. Bear in mind that, like SI, EMI is=20
> not just one=20
> phenomenon. Rather, it's a host of different electrical and=20
> EM phenomena,=20
> any one of which can cause you EMI problems. I agree with=20
> Charles that=20
> consulting an experienced EMC engineer during the early phase=20
> of a board's=20
> design is the best way to manage EMI-related risk.
>=20
> Regards,
>=20
> Ron Matthews
> Principal MTS
> Signal Integrity/EMI
> Charles Stark Draper Laboratory
> 555 Technology Square
> Cambridge, MA 02139
> Voice: 617-258-2519
>=20
>=20
> At 11:12 PM 12/2/2004 -0800, Chris Cheng wrote:
> >You mean the =3D22 part ? :-D
> >
> >Seriously, I know it is understandable and explainable but I=20
> want it to=20
> >be automatically predicted and simulated by a tool. It is=20
> easy to fix=20
> >and patch after the fact but I have yet to see a tool to=20
> tell me ahead=20
> >of time the db and peaks location. A bare PCB with a few=20
> "experimental=20
> >traces" as in some EMI papers, sure. A multi-boards system=20
> with chassis=20
> >and spaghetti cables come out ? Show me the money.
> >
> >-----Original Message-----
> >From: Charles Grasso
> >To: Chris.Cheng@xxxxxxxxxxxx; zhang_kun@xxxxxxxxxx;=20
> >si-list@xxxxxxxxxxxxx
> >Sent: 12/2/2004 10:31 PM
> >Subject: RE: [SI-LIST] Re: EMI simulation tools at PCB level
> >
> >Chris - It would be *much* easier for you to contact some=20
> experienced=20
> >EMC engineers - the phenomena you describe are understandabe and
> >explainable.
> >
> >-----Original Message-----
> >From: si-list-bounce@xxxxxxxxxxxxx=20
> >[mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of Chris Cheng
> >Sent: Thursday, December 02, 2004 5:13 PM
> >To: 'zhang_kun@xxxxxxxxxx'; si-list@xxxxxxxxxxxxx
> >Subject: [SI-LIST] Re: EMI simulation tools at PCB level
> >
> >
> >I am sure the consumer product guys will laugh at my stupidity but I=20
> >can never design a PCB that will pass FCC B without a large=20
> metal cage=20
> >chassis. I've always wanted to simulate why if I tighten the=20
> screw by=20
> >one more turn
> >on my door and my EMI gaskets compressed a little harder and the
> >signature
> >changed by 10 db.  Or if I hang the cable this way or that way the
> >signature
> >changed by a few db. What I am trying to say is while EMI=20
> from PCB may
> >be
> >the source, the enclosure/environment the PCB is in seems to have a
> >bigger
> >impact on whether you are passing FCC than the PCB itself.=20
> Granted this
> >is
> >just from an incompetent designer like me who cannot ship an absolute
> >clean
> >PCB that can be wrapped in a plastic bag and passing FCC.=20
> Any simulation
> >tools that can help me ?
> >
> >ps Is there any way I can receive messages from the list=20
> from outside=20
> >the US without these =3D2 =3D22 ? I know the US or English=20
> language is not=20
> >the center
> >of the Universe so I appolgize in advanced.
> >------------------------------------------------------------------
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