RE: [SI-LIST] : Broadside v edge coupled striplines

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From: Aubrey_Sparkman@Dell.com
Date: Fri Jan 19 2001 - 11:25:33 PST


Scott,
You have pointed out good ways to reduce those two factors, not eliminate
them, right? Do you have manufacturing data to how much reduction in
variation?

And CPW is an Edge-coupled system, right?

And I hope everyone realizes my comment about Compaq and Sun was made in
fun.

And I do know how to spell Broad Side, even if Outlook does not.

Aubrey Sparkman
Signal Integrity
Aubrey_Sparkman@Dell.com
(512) 723-3592

> -----Original Message-----
> From: Scott McMorrow [mailto:scott@vasthorizons.com]
> Sent: Friday, January 19, 2001 12:00 PM
> To: Aubrey_Sparkman@exchange.dell.com
> Cc: ldmiller@rhapsodynetworks.com; ribrooks@nortelnetworks.com;
> SI-LIST@silab.eng.sun.com
> Subject: Re: [SI-LIST] : Broadside v edge coupled striplines
>
>
> Aubrey,
>
> The manufacturing issues can be reduced by constructing the
> broadside pair on core material and keeping the spacing between
> the pairs small compared to the spacing to the planes. Then the
> separation between the pair is well controlled and the fields are
> well contained between the pairs.
>
> Another solution which works quite well is to use CPW or
> grounded CPW construction for diff pairs on outer layers.
>
>
> regards,
>
> scott
>
> --
> Scott McMorrow
> Principal Engineer
> SiQual, Signal Quality Engineering
> 18735 SW Boones Ferry Road
> Tualatin, OR 97062-3090
> (503) 885-1231
> http://www.siqual.com
>
>
> Aubrey_Sparkman@Dell.com wrote:
>
> > Thanks for that correction. Isn't the difference is really in
> > manufacturing, not physics? An EDGE-coupled diff pair is
> more uniform
> > because the pattern is etched in the same process. The
> BROADSICE-coupled
> > diff pair is etched at two different times and additionally
> has to be
> > mechanically aligned for lamination. This adds two
> additional error terms
> > to the accuracy of your BROADSICE-coupled diff pair that
> the EDGE-coupled
> > diff pair does not have. So IMHO, you should really have a
> packing density
> > problem before you consider using BROADSICE-coupled traces.
> >
> > But if you are doing work for Compaq or Sun, you should use
> > BROADSICE-coupled diff pairs whenever possible. :-)
> >
> > Aubrey Sparkman
> > Signal Integrity
> > Aubrey_Sparkman@Dell.com
> > (512) 723-3592
> >
> >
> >
>
>
>
>



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