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

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From: Scott McMorrow (scott@vasthorizons.com)
Date: Fri Jan 19 2001 - 23:16:46 PST


Ron,

I would agree. Just trying to dispel the blanket statement that
broadside should be avoided due to manufacturing issues. There
are ways to engineer a board and reduce the tolerance issues
with broadside traces. Trace density is, of course, a seperate
issue.

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

Ron Miller wrote:

> Hi scott > > Broadside lines require more real estate than edge coupled > lines. If you have the real estate that is good. We do not. > > If you disagree the contention that broadside requires more > real estate please e-mail me and I will fill in the details. > > ron Miller > > -----Original Message----- > From: Scott McMorrow [mailto:scott@vasthorizons.com] > Sent: Friday, January 19, 2001 10:00 AM > To: Aubrey_Sparkman@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 > > > > > > > > **** To unsubscribe from si-list or si-list-digest: send e-mail to > majordomo@silab.eng.sun.com. In the BODY of message put: UNSUBSCRIBE > si-list or UNSUBSCRIBE si-list-digest, for more help, put HELP. > si-list archives are accessible at http://www.qsl.net/wb6tpu > **** > > **** To unsubscribe from si-list or si-list-digest: send e-mail to > majordomo@silab.eng.sun.com. In the BODY of message put: UNSUBSCRIBE > si-list or UNSUBSCRIBE si-list-digest, for more help, put HELP. > si-list archives are accessible at http://www.qsl.net/wb6tpu > ****

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