Doug, Well put. Lee W. Ritchey Speeding Edge P. O. Box 2194 Glen Ellen, CA 95442 Phone- 707-568-3983 FAX- 707-568-3504 I just used the energy it took to be angry to write some blues. Count Basie > [Original Message] > From: Doug Smith <doug@xxxxxxxxxx> > To: <jose_moreira@xxxxxxxxxxx> > Cc: <si-list@xxxxxxxxxxxxx> > Date: 10/26/2004 3:04:16 PM > Subject: [SI-LIST] Re: Split Ground Planes > > 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 > ------------------------------------------------------------------ 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