Sorry, the formula given by he link was: L =3D (U0Ur/PI) * cosh^-1(centre-to-centre-dist/w); I have no idea if this accounts (somehow!) for mutual inductance and is taking it from trace inductance.... -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of Steve Weir Sent: 08 February 2005 07:35 To: joepaulm@xxxxxxxxxxxxx; si-list@xxxxxxxxxxxxx Subject: [SI-LIST] Re: inductance of differential stripline That is correct it is lower than 2X. Istvan only offered the description=20 as an approximation to help with Mark's intuitive understanding. Steve At 12:12 PM 2/8/2005 +0550, Joe Paul wrote: >Sir, > >Excuse me and Correct me if I am wrong > >I feel that the inductance of the differential line measured by applying a=20 >differential signal on a >pair of differential traces, will be less than the twice the inductance >measured by applying a >single ended signal on a trace , as the magnetic field formed due to=20 >current in one traces aiding >the current flow other. > >i.e differential inductance will be, equlaent to 2 single ended=20 >inductances in series and their >mutual inductance between them in parallel. > >I don't know about the accuracy the tool Iused , but Inductance calculated=20 >shows that the mutual >inductance are not that small to be ignored. >(as per Inductance calculator at http://emcsun.ece.umr.edu/new-induct/ ) > >My assumptions are >* Single ended inductance measured with no other lines in its vicinity. >* Differential inductance measured with no other lines other than them. > > > >Joe >Ordyn,India. > > > Mark, > > > > Welome to the si-list forum. > > > > In a very simplistic way we can say that the differential impedance > > is twice the single-ended impedance because we connect two > > transmission lines in series. Series impedances add, similarly > > series-connected inductances add. You can use the same > > formula of Zo*delay, just have to substitute the correct terms: > > differential impedance and differential (odd-mode) delay. > > You can find very good tutorials on the subject on the TDA > > Systems website. http://www.tdasystems.com/ > > > > Regards, > > > > Istvan Novak > > SUN Microsystems > > > > Mark Burford wrote: > > > > >Hi guys, just subscribed. > > >I understand the inductance of stripline to be Z0*delay_of_line > > >Could anyone tell me what the inductance is for differential odd mode > > >stripline please? Does it change? I know Z0 for differential stripline > > >is near double that of single stripline, but does this affect > > >inductance? > > > > > >Many thanks > > > > > >Mark Burford > > >Mburford AT xyratex DOT 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 >------------------------------------------------------------------ >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 > The weirsp@xxxxxxxxxx e-mail address will terminate March 31, 2005. 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