Re: [SI-LIST] : RE: RC terminations on multidrop busses

Roy Leventhal (Roy_Leventhal@mw.3com.com)
Fri, 13 Nov 1998 13:20:32 -0600

Thanks Vinu,

Your explanation has improved my understanding of the numbers I've been
seeing in my Cadence simulator.

Best Regards,

Roy

Vinu Arumugham <vinu@cisco.com> on 11/13/98 11:22:02 AM

To: Roy Leventhal/MW/US/3Com
cc:
Subject: Re: [SI-LIST] : RE: RC terminations on multidrop busses

Roy,

When you have unterminated stubs, the reflections from the stubs go back
into the trunk line and aid the wave traveling to the farthest destination.
If you terminate the stubs and therefore reduce the reflection (by
absorbing
signal energy in the R of the RC) that goes back to the trunk line, the
wave on the trunk line will take more time (slower edge) to reach the
farthest destination. Depending on the timing margins of your design, this
may be
acceptable. I think the interactions are complex enough to need simulation.

Thanks,
Vinu

Roy Leventhal wrote:

> 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?
>
> Best Regards,
>
> Roy
>
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