[SI-LIST] Re: near and far end crosstalk in frequency domain
- From: Zhangkun <zhang_kun@xxxxxxxxxx>
- To: Istvan.Novak@xxxxxxx
- Date: Tue, 08 Jun 2004 22:38:33 +0800
Dear Istvan
How to improve it? I really doubt the far end measurement, too. Why the far end
need more strict isolation?
Best Regards
Zhangkun
2004.6.8
----- Original Message -----
From: "Istvan Novak" <Istvan.Novak@xxxxxxx>
To: <zhang_kun@xxxxxxxxxx>
Cc: "Istvan NOVAK" <istvan.novak@xxxxxxxxxxxxxxxx>; "si-list"
<si-list@xxxxxxxxxxxxx>
Sent: Tuesday, June 08, 2004 9:46 PM
Subject: Re: [SI-LIST] Re: near and far end crosstalk in frequency domain
> Dear Zhangkun,
>
> Measuring far-end crosstalk with no reference plane is trickier than
> near-end crosstalk. You may need higher isolation in the connecting
> cables' braids. If you already have some means to break the ground
> loop between the two VNA ports, look at it and try to improve on it
> and repeat the measurement.
>
> Regards,
> Istvan
>
>
> have to make
> Zhangkun wrote:
> >
> > Dear Istvan
> >
> > I am analyzing crosstalk at low frequency. The length of transmission line
> > is much less than the wave length.
> >
> > From the tele-formular, it could be gotten that the polarity of electrical
> > coupling and magnetic coupling are same at the near end and are adverse at
> > the far end. Therefore, I think the farend crosstalk is less than near end
> > crosstalk in frequency domain. This is verified by simulation in HSPICE,
> > ANSOFT. I do not consider that in time domain, which has been considered in
> > a lot of books.
> >
> > By the way, this is still the topic about crosstalk between differential
> > pairs without reference plane. I have gotten good result about near end
> > crosstalk. But there is still some problem about the far end. I am sure my
> > measurement is right : )
> >
> > Best Regads
> >
> > Zhangkun
> > 2004.6.8
> > ----- Original Message -----
> > From: "Istvan NOVAK" <istvan.novak@xxxxxxxxxxxxxxxx>
> > To: <zhang_kun@xxxxxxxxxx>; "si-list" <si-list@xxxxxxxxxxxxx>
> > Sent: Tuesday, June 08, 2004 8:11 PM
> > Subject: Re: [SI-LIST] near and far end crosstalk in frequency domain
> >
> > > Dear Zhangkun,
> > >
> > > Unless you have a perfectly homogeious cross section of
> > > material that carries the field, there is always a far-end
> > > crosstalk component, even if you have perfect termination.
> > > One major difference between near-end and far-end
> > > crosstalk is that far-end crosstalk saturates at full coupling.
> > > This means that beyond a certain frequency, the far-end
> > > crosstalk response may be bigger than the near-end crosstalk
> > > response. 'May be' refers to the fact that both near-end and
> > > far-end crosstalk vary sinusoidally with frequency, but with
> > > different periodicity: near-end crosstalk's periodicity depends
> > > on the electrical length of coupled section, far-end crosstalk's
> > > periodicity depends on the electrical length of coupled section
> > > AND the strength of coupling.
> > >
> > > Regards,
> > >
> > > Istvan
> > >
> > >
> > > ----- Original Message -----
> > > From: "Zhangkun" <zhang_kun@xxxxxxxxxx>
> > > To: "si-list" <si-list@xxxxxxxxxxxxx>
> > > Sent: Monday, June 07, 2004 11:02 PM
> > > Subject: [SI-LIST] near and far end crosstalk in frequency domain
> > >
> > >
> > > > Dear all
> > > > Now, we are analyzing the crosstalk between transmission line. There is
> > > something interesting. The far end crosstalk is larger than the near end
> > > crosstalk in frequency domain. Have anybody meet the similar problem?
> > > >
> > > > Best Regards
> > > >
> > > > Zhangkun
> > > > 2004.6.8
> > > >
> > > >
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> --
> Istvan Novak Sun Microsystems, Inc.
> Istvan.Novak@xxxxxxx Workgroup Servers, BDT Group,
> One Network Drive, Burlington, MA 01803
> Phone: (781) 442 0340
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