My thanks to all and especially Jon Elson for an enlightening little session
on this subject.  I would otherwise have no way of anticipating the
consequences of this idea.


regards,
Tim Hutcheson
[EMAIL PROTECTED]




> -----Original Message-----
> From: Jon Elson [mailto:[EMAIL PROTECTED]]
> Sent: Monday, August 06, 2001 6:20 PM
> To: Protel EDA Forum
> Subject: Re: [PEDA] 5/5 Manufacturing Issues
>
>
>
>
> Mike Reagan wrote:
>
> > source termination allows the signal to reflect off the load and
> > > travel back to the source, where is absorbed by series
> termination. > > >
> >
> > And I will bet his analysis was done with  sine wave reflections not  a
> > rising edge of a pulse.   Try  a simple experiment,   pick a design you
> > already have on the bench,  replace the resistor with  10 ohms
> then replace
> > it with 50,   Get a high speed scope and measure the leading edges.
> > If you apply his theory you are playing games with bouncing
> spikes back and
> > forth.. which .equals a very noisy board.  The name of the game
> is to keep
> > the spikes from being generated in the first place   not spike
> management.
> > I guess you could do spike management but I prefer  the first
> method.    Try
> > the bench test   and look at the edge.  I had a very good rf engineer
> > explain then he showed me.
>
> Yes, but once we get down to specifics with line length and Tr,
> the picture
> changes.  If the Tr is less than the one-direction Tp (propagation delay)
> of the line, then the reflection problem is a bear, and must be
> dealt with.
> If the Tp is MUCH less than the Tr (as it was in this particular
> case) then
> the reflection is 'distributed' across many reflections of the
> partial rising
> (or falling) edge.  This makes for wave shape distortion, but the
> reflection
> is much smaller.  In between these two cases, the reflection is in between
> minimal and full scale.
>
> Jon

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* To post a message: mailto:[EMAIL PROTECTED]
*
* To leave this list visit:
* http://www.techservinc.com/protelusers/leave.html
*                      - or email -
* mailto:[EMAIL PROTECTED]?body=leave%20proteledaforum
*
* Contact the list manager:
* mailto:[EMAIL PROTECTED]
*
* Browse or Search previous postings:
* http://www.mail-archive.com/proteledaforum@techservinc.com
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * *

Reply via email to