I would wonder why your antipads are so large. If there is room to run a trace between pins, there is room to have a plane web underneath the traces. The impedance of the trace will certainly go up in this area and if there are several sets of pads in a row, you will see an impedance increase. 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: steve weir <weirsi@xxxxxxxxxx> > To: <jain.nitin@xxxxxxxxx>; <si-list@xxxxxxxxxxxxx> > Date: 12/8/2005 1:08:31 AM > Subject: [SI-LIST] Re: Gigabit traces on Backplane > > Nitin, FYI attachments don't generally make it to postings. Variation in > channel geometry does cause impedance variations. Whether it is enough to > be a problem or not depends on a number of other factors. > > Steve. > At 02:12 PM 12/8/2005 +0530, jain.nitin@xxxxxxxxx wrote: > > >=0D > >Hello, > > > >Enclosed is the snapshot of Gigabit traces (differential) running on the > >Backplane in my design. The Blue color shows the traces in one signal > >layer and green color shows the ground plane.=0D > > > >Now if you look closely, you will find that at some places, the plane is > >not there for the differential trace because of the Antipads. Although > >this for a short segment only. > > > >Could somebody let me know if this is okay or any problems are expected > >because of this. Will this cause any impedance discontinuity. > > > >With regards, > >Nitin Jain > > > > > > > >Confidentiality Notice=0D > > > >The information contained in this electronic message and any attachments to= > > this message are intended > >for the exclusive use of the addressee(s) and may contain confidential or= > > privileged information. If > >you are not the intended recipient, please notify the sender at Wipro or= > > Mailadmin@xxxxxxxxx immediately > >and destroy all copies of this message and any attachments. > >------------------------------------------------------------------ > >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 > ------------------------------------------------------------------ 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