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

Dave, no problem.

Best Regards,

Steve
DAVID CUTHBERT wrote:
> 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 
> <mailto: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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>     --
>     Steve Weir
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-- 
Steve Weir
Teraspeed Consulting Group LLC 
121 North River Drive 
Narragansett, RI 02882 

California office
(866) 675-4630 Business
(707) 780-1951 Fax

Main office
(401) 284-1827 Business 
(401) 284-1840 Fax 

Oregon office
(503) 430-1065 Business
(503) 430-1285 Fax

http://www.teraspeed.com
This e-mail contains proprietary and confidential intellectual property of 
Teraspeed Consulting Group LLC
------------------------------------------------------------------------------------------------------
Teraspeed(R) is the registered service mark of Teraspeed Consulting Group LLC

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