Check at http://www.tdasystems.com/Appnotes/diff1199.pdf -Ray Sun Microsystems Inc. > > >Hi Allen, >Do u have a url where I can directly go to the paper. >Thanks, >Rahul. >--- Michael Allen <mallen@xxxxxxxxxxxxxxx> wrote: >> >> Alexis, >> The odd mode impedance should be approximately >> equal to half of >> the differential impedance and the even mode should >> be as high as >> possible. TDA systems has a very good paper on the >> subject. >> >> Mike Allen >> Principal Engineer, Signal Integrity >> TeraConnect, Inc >> Nashua, NH >> >> >> > -----Original Message----- >> > From: Alexis LESTRA [SMTP:alestra@xxxxxxxxxx] >> > Sent: Tuesday, June 12, 2001 11:58 AM >> > To: si-list@xxxxxxxxxxxxx >> > Subject: [SI-LIST] Even/Odd mode impedance >> >=20 >> >=20 >> > Dear all, >> >=20 >> > I am new in the field of signal integrity and >> would like to submit a=20 >> > basic problem. I am currently designing a >> backplane for differential=20 >> > signals at 2.5 Gbit/s. The receiver is >> differential, with 100 Ohm=20 >> > termination. For coupled transmission lines, which >> characteristic=20 >> > impedance should match 50 Ohm, the even-mode >> impedance or the >> > even-mode=20 >> > impedance ? After reading some documentation on >> the topic, I am=20 >> > confused. On one hand, I read that differential >> signals propagate in=20 >> > odd-mode since coupled transmission lines are >> driven with equel=20 >> > magnitude and 180=B0 out of phase ("High-speed >> Digital System = >> Design",=20 >> > S.H. Hall, G.W. Hall, J.A. McCall, p.53) . On the >> other hand, I read=20 >> > that since differential signals are launched from >> silicon devices, >> > the=20 >> > gates that driver these signals are both >> referenced to ground,=20 >> > resulting in even-mode coupling =20 >> > (http://www.amp.com/simulation/files/papers/98060A >> 5.pdf p.19). >> > Can anyone help me to clarify this point. >> >=20 >> > Thanks in advance. >> >=20 >> > Alexis >> >=20 >> > Alexis Lestra >> > Tachys Technologies >> > Les Algorithmes, Batiment Aristote A >> > 2000, route des Lucioles >> > F-06901 Sophia-Antipolis Cedex >> >=20 >> > >> >------------------------------------------------------------------ >> > To unsubscribe from si-list: >> > si-list-request@xxxxxxxxxxxxx with 'unsubscribe' >> in the Subject field >> > For help: >> > si-list-request@xxxxxxxxxxxxx with 'help' in the >> Subject field >> >=20 >> > List archives are viewable at: >> > //www.freelists.org/archives/si-list=20 >> > Old list archives are viewable at: >> http://www.qsl.net/wb6tpu >> > =20 >> >=20 >> >------------------------------------------------------------------ >> To unsubscribe from si-list: >> si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in >> the Subject field >> For help: >> si-list-request@xxxxxxxxxxxxx with 'help' in the >> Subject field >> >> List archives are viewable at: >> //www.freelists.org/archives/si-list >> Old list archives are viewable at: >> http://www.qsl.net/wb6tpu >> >> > > >__________________________________________________ >Do You Yahoo!? >Get personalized email addresses from Yahoo! Mail - only $35 >a year! http://personal.mail.yahoo.com/ >------------------------------------------------------------------ >To unsubscribe from si-list: >si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field >For help: >si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field > >List archives are viewable at: //www.freelists.org/archives/si-list >Old 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 For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List archives are viewable at: //www.freelists.org/archives/si-list Old list archives are viewable at: http://www.qsl.net/wb6tpu