Yeah, A small series resistor can interact with the capacitance of the 
transmission line to limit the slew rate and act as a rudimentary low pass 
filter.  And it still form a match as long as the resistance plus the output 
impedance of the driver roughly equal the characteristic impedance of the 
transmission line.

Regards,

Jeff Condit

----- Original Message ----- 
From: "Jon Elson" <[EMAIL PROTECTED]>
To: "Jeff Condit" <[EMAIL PROTECTED]>; "Protel EDA Discussion List" 
<[email protected]>
Sent: Friday, January 25, 2008 10:37 AM
Subject: Re: [PEDA] Advice needed...


>
>
> Jeff Condit wrote:
>
>>How many things get clocked along the line?  If there is only one then 
>>series termination at the source works well.  If there are multiple things 
>>to be clocked along the line, then parallel termination at the end is in 
>>order.
>>
> Good point, a full impedance match series termination will muck up the 
> signal
> except at the far end.  But, far end termination won't help the radiation 
> (unless it is the
> ringing on the line that is causing the radiation.)  In some cases, a 
> small series resistor
> at the source can reduce EMI without wrecking the signal characteristics 
> in the middle.
>
>>
> Jon
>
>
>
> -- 
> No virus found in this incoming message.
> Checked by AVG. Version: 7.5.516 / Virus Database: 269.19.11/1243 - 
> Release Date: 1/25/2008 11:24 AM
>
> 


 
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