[SI-LIST] Re: Split Ground Planes
- From: Doug Smith <doug@xxxxxxxxxx>
- To: jose_moreira@xxxxxxxxxxx
- Date: Tue, 26 Oct 2004 15:04:15 -0700
Hi Jose and the group,
I normally reply personally to people to avoid the glut of
"out-of-office" messages, but feel I needed to add to this discussion.
Signal propagation is an important but small part of the trouble you
can get into with split planes if not implemented properly. Even if
you manage to get the signal propagation right, system reliability can
be severely compromised as it is easy to turn every cable in the
system into a great receiving array to pick up impulses you can easily
miss in the lab, but your customers won't!
I worry also about the common mode voltage that can result across the
board and drive enclosures, cables, etc. This voltage will cause
radiation that depends on a lot more that the board itself. Also
common mode voltages can be developed from outside sources as
mentioned above.
There are probably thousands of modes to get in trouble with split
planes of which the referenced paper covers a subset. You can cover
many of the problems by not ever allowing a trace to cross the slit.
Even DC signals like LEDs are generally too noisy to allow to cross a
slit in many cases.
Most of the examples of splitting up ground planes I have seen were
not necessary and just caused problems (remember that at high
frequencies everything is connected together whether you want them to
be or not, lots of articles on my website about this effect). There
are a few justified cases though. Video can be one example where the
signal can be degraded by just a small amount of powerline current
(hum bars in the video).
In general, I would not recommend splitting planes unless you can
state and MEASURE (to confirm) why a split plane is needed.
Doug
jose_moreira@xxxxxxxxxxx wrote:
> Nikhil,
>
> you can find the article on the IEEE xplore site (if you have acess) or =
> in a library.
>
> Details:
>
> Signal propagation and radiation of single and differential microstrip =
> traces over split image planes
> Orhanovic, N.; Raghuram, R.; Matsui, N.;
> Electromagnetic Compatibility, 2000. IEEE International Symposium on =
> ,Volume: 1 , 21-25 Aug. 2000=20
> Pages:339 - 343 vol.1
>
> Best Regards
> Jose
>
> -----Original Message-----
> From: si-list-bounce@xxxxxxxxxxxxx
> [mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of Nagel, Michael
> Sent: Dienstag, 26. Oktober 2004 16:39
> To: si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] Re: Split Ground Planes
>
>
> Nikhil,
>
> There is a quite instructive paper with the title:
>
> Signal Propagation and Radiation of Single and Differential
> Microstrip Traces Over Split Image Planes
>
> written by:
> N. Orhanovic, R. Raghuram, N. Matsui
> from: Applied Simulation Technology
> e-mail: { neven, raghu, matsui} @apsimtechcom
>
> Unfortunately I have no direct link to the document.
>
> Generally spoken - the split plane itself may not be
> harmful in terms of EMI unless you start routing=20
> traces across the gap!
>
> Best regards,
> Michael
>
>
> -----Original Message-----
> From: Nikhil Patel [mailto:npatel@xxxxxxxxxxxxxxxxxxx]
> Sent: Dienstag, 26. Oktober 2004 15:40
> To: si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] Split Ground Planes
>
>
> Hi all,
> =20
>
> I have been doing a lot of reading on Split ground planes and am a bit
> confused now. Do most people use just one solid ground in the schematic =
> and
> layout for EMI issues or do you prefer split ground planes? Any input is
> greatly appreciated.=20
>
> =20
>
> Thanks
>
> =20
>
> Nikhil=20
>
> =20
>
>
>
> ------------------------------------------------------------------
> To unsubscribe from si-list:
> si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
>
> or to administer your membership from a web page, go to:
> //www.freelists.org/webpage/si-list
>
> For help:
> si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
>
> List FAQ wiki page is located at:
> http://si-list.org/wiki/wiki.pl?Si-List_FAQ
>
> List technical documents are available at:
> http://www.si-list.org
>
> List archives are viewable at: =20
> //www.freelists.org/archives/si-list
> or at our remote archives:
> http://groups.yahoo.com/group/si-list/messages
> Old (prior to June 6, 2001) list archives are viewable at:
> http://www.qsl.net/wb6tpu
> =20
> ------------------------------------------------------------------
> To unsubscribe from si-list:
> si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
>
> or to administer your membership from a web page, go to:
> //www.freelists.org/webpage/si-list
>
> For help:
> si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
>
> List FAQ wiki page is located at:
> http://si-list.org/wiki/wiki.pl?Si-List_FAQ
>
> List technical documents are available at:
> http://www.si-list.org
>
> List archives are viewable at: =20
> //www.freelists.org/archives/si-list
> or at our remote archives:
> http://groups.yahoo.com/group/si-list/messages
> Old (prior to June 6, 2001) list archives are viewable at:
> http://www.qsl.net/wb6tpu
> =20
>
> ------------------------------------------------------------------
> To unsubscribe from si-list:
> si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
>
> or to administer your membership from a web page, go to:
> //www.freelists.org/webpage/si-list
>
> For help:
> si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
>
> List FAQ wiki page is located at:
> http://si-list.org/wiki/wiki.pl?Si-List_FAQ
>
> List technical documents are available at:
> http://www.si-list.org
>
> List archives are viewable at:
> //www.freelists.org/archives/si-list
> or at our remote archives:
> http://groups.yahoo.com/group/si-list/messages
> Old (prior to June 6, 2001) list archives are viewable at:
> http://www.qsl.net/wb6tpu
>
>
>
>
--
-------------------------------------------------------
___ _ Doug Smith
\ / ) P.O. Box 1457
========= Los Gatos, CA 95031-1457
_ / \ / \ _ TEL/FAX: 408-356-4186/358-3799
/ /\ \ ] / /\ \ Mobile: 408-858-4528
| q-----( ) | o | Email: doug@xxxxxxxxxx
\ _ / ] \ _ / Website: http://www.dsmith.org
-------------------------------------------------------
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List FAQ wiki page is located at:
http://si-list.org/wiki/wiki.pl?Si-List_FAQ
List technical documents are available at:
http://www.si-list.org
List archives are viewable at:
//www.freelists.org/archives/si-list
or at our remote archives:
http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
Other related posts:
