FreeLists / si-list / [SI-LIST] Re: inductance of differential stripline

[Steve Weir <weirsi@xxxxxxxxxx>]

That is correct it is lower than 2X.  Istvan only offered the description 
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 
>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 
>current in one traces aiding
>the current flow other.
>
>i.e differential inductance will be, equlaent to 2 single ended 
>inductances in series and their
>mutual inductance between them in parallel.
>
>I don't know about the accuracy the tool Iused , but Inductance calculated 
>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
> > >
> > >
> > >
> > >
> >
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