Hi Mike, Basically I think you are right. However the coupling between the two signal traces and ground determines how much return current go through ground. For example, if the two signal traces are well separated, the return current will be mostly through ground. If the two signal traces are tightly coupled and far to ground (e.g., twist pair), most return currnt will be on one trace. Thanks, Ke --- Michael Kotson <mkotson@xxxxxxxxxxx> wrote: > Hello Gurus, > I have a question regarding the return current > for a high speed > differential signal. I've seen a couple of sources > that state that all > of the signal return current is handled by the other > half of the > differential pair. It seems more logical to me that > there must be some > amount of return current (not just common mode) on > the reference > plane(s) as well. What's the truth? > > > > Thanks in advance, > > Mike > > > > Michael Kotson > > Project Engineer > > VT Miltope > > 4900 Pearl East Circle Suite 106 > > Boulder, CO 80301 > > (303) 473-0388 x132 > > http://www.miltope.com <http://www.miltope.com/> > > > > > > > > ****************************************************************************** > CONFIDENTIALITY NOTE: This email and any > attachments may be confidential > and protected by legal privilege. If you are not > the intended recipient, > be aware that you are hereby notified that any > unauthorized review, use, > disclosure, dissemination, distribution, or copying > of this communication, > or any of its contents, is strictly prohibited. If > you have received this > email in error, please notify us immediately by > replying to the sender and > deleting this copy and the reply from your system. > Thank you for your cooperation. > ****************************************************************************** > ------------------------------------------------------------------ > 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 > > > __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com ------------------------------------------------------------------ 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