Regards,
Alok
On Fri, 13 Nov 1998, Bob Davis wrote:
> Magnus,
>
> The RC termination is usually the same as the AC termination that you think
> about. It does not matter which is first in the R - C coupling to
> ground(signal return). When this is designed, the Resistor is the energy
> absorption terminating element and the Capacitor is for the DC isolation.
> The Resistor is chosen to match the line impedance at the point of
> termination and the capacitor is chosen to couple the resistor for the high
> frequencies of the edge and discharge prior to the next edge.
>
> I like the resistor at the ground(signal return) end to make the observation
> of the termination voltage more easily seen. The circuit still works the
> same with either order of R and C.
>
> Using this termination on stubs has worked for me to reduce multiple
> reflections back to the normal line provided the stub is long enough to
> adopt a transmission line propagation mode at the frequencies.
>
> Good luck.
>
> Bob Davis, Consulting Engineer.
> Summit Computer Systems, Inc
> Signal Integrity Specialists - High Speed, Critical PCB Design
> 408-353-2706
> [email protected] , www.scsi.com
>
>
> -----Original Message-----
> From: [email protected]
> [mailto:[email protected]] On Behalf Of Magnus Homann
> Sent: Friday, November 13, 1998 8:37 AM
> To: [email protected]
> Cc: [email protected]
> Subject: Re: [SI-LIST] : RE: RC terminations on multidrop busses
>
>
> > Abe,
> >
> > Thanks for your reply.
> >
> > If I read it correctly, you are talking about RC terminations at each end
> > of the backplane line. Have you ever looked into RC terminations at the
> > receivers / drivers on the daughter board stubs?
>
> I have to ask,
>
> Is the RC termination you mentioned the same as an AC-termination (cap+res
> to ground from signal) or is it a low-pass filter (res in series with
> signal,
> cap to ground). I've seen both used, but have never found a reason to use
> either in my designs. Yet.
>
> Magnus Homann
> Ericsson Mobile Data Design AB
>
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