[SI-LIST] Re: [Help] How to do termination in differential signal with series termination ?

Steve,
in my haste I was thinking double termination ah la video. You are right.
Nothing needs to be done at the driver.

   Dave


On 12/4/08, steve weir <weirsi@xxxxxxxxxx> wrote:
>
> Parallel terminations absorb energy at the far end and is related only
> to the channel, not the driver Z.    Also, you've got your impedances
> backward.
>
> Steve.
> King Da wrote:
> > Hi,Folks,
> > I have a differential pair which odd mode impedance is 48 Ohm and even
> mode
> > impedance is 108 Ohm by TDR measurement.
> > I would like use 100 Ohm for differential termination at far end, but how
> to
> > choose series termination resistor for each trace at near end?
> >
> > I refered Bogatin's "Signal Integrity:Simplified" book that said parallel
> > termination R2 equal Zeven, So, I should use 108 Ohm subtract 20 Ohm of
> my
> > driver's Ro is 88 Ohm for my series termination at near end, am I right?
> >
> > The Rseries = 108 (Zeven) - 20 (Driver's Ro) = 88 Ohm, right ?
> >
> > Does the differential termination resistor is 100 Ohm better than 91Ohm ?
> >
> > Thanks,
> >
> > Yardala
> >
> >
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