Re: [SI-LIST] : Transmission line termination

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From: Vinu Arumugham (vinu@cisco.com)
Date: Fri Apr 06 2001 - 09:36:12 PDT


And DC drive current requirement. A Vtt termination requires equal but
smaller driver Ioh and Iol. A termination to ground will require large Ioh
to guarantee logic levels.

Thanks,
Vinu

Scott McMorrow wrote:

> Sunil,
>
> The average DC level is different.
>
> Terminating to a Vtt that is near the switching threshold causes a
> signal swing which is relatively symmetric about the threshold. This
> is the case with SSTL-2 signalling.
>
> scott
>
> sunil-chandra.kasanyal@st.com wrote:
>
> > Hello all,
> > What is the difference between these two terminations?Why?
> > 1)
> > -----------------------
> > DRIVER->-----| TRANSMISSION LINE |-------------RECIEVER
> > ----------------------- \
> > Zo=50ohms /Rtt=50ohms
> > \
> > /
> > ---GND
> > 2)
> >
> > -----------------------
> > DRIVER->-----| TRANSMISSION LINE |-------------RECIEVER
> > ----------------------- \
> > Zo=50ohms /Rtt=50ohms
> > \
> > /
> > ------TERMINATION VOLTAGE=Vtt
> >
> > If signals of 5V come from drivers,no reflection will take place at the
> > reciever ends.Since in above two cases,way of termination is
> > different,what exactly the different uses of these two terminations.
> >
> > Regards
> > Sunil
> >
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> --
> Scott McMorrow
> Principal Engineer
> SiQual, Signal Quality Engineering
> 18735 SW Boones Ferry Road
> Tualatin, OR 97062-3090
> (503) 885-1231
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>
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