Actually Doug unless Polars Si6000 impedance calculator is wrong the answer is yes. trace width 11.97/12.97 mils, separation 5.323 mils, 1.2 mil thick, 16 mils above plane, Er 4.2 Differential impedance 100 ohms, Z odd 50, Z even 99.99 Zcommon 50 I've attached a jpeg screenshot, which the list will strip off, but you should get it. Dave Instone Oxford Semiconductor Ltd 25 Milton Park Abingdon Oxon ox14 4sh UK www.oxsemi.com +44 (0)1235 824963 Doug Brooks wrote: > Actually, the answer is no. > > Zdiff = 2*Zo(1 - k) > Zcommon = .5 * Zo(1 + k) > > where k is a factor related to the coupling between the traces (and > whose limits are between 0 and 1.0). > > Single-ended impedance and common mode impedance of a differential > pair have different meanings. > > Doug Brooks > > > > > At 06:48 AM 11/21/2006, you wrote: > >> Hello All, >> One basic question on differential pair trace >> impedance. Is it possible that a differential pair with 100 ohm >> differential impedance will have 50 ohm common mode impedance? Are >> the single-ended and common mode impedances of a differential pair >> has the same meaning? >> Thanks and advance, >> shekh >> >> >> >> __________________________________________________________ >> Yahoo! India Answers: Share what you know. Learn something new >> http://in.answers.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 >> >> > > ____________________________________________________________________________- > Check out UltraCAD's differential impedance and skin effect > calculators at http://www.ultracad.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 > > > > > -- Binary/unsupported file stripped by Ecartis -- -- Type: image/jpeg -- File: common.jpg ------------------------------------------------------------------ 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