I'm not sure if I'm answering the same question you are asking,
but without doing a complicated formula, I heard a "rule of thumb"
(insert your favorite disclaimer here)
that if the gap between pairs is "5x the trace width" the cross-
talk is virtually nonexistent. I've used "3x the trace width" for years
with no ill effects.

Proper routing of a pair (matched lengths, minimized discontinuities,
etc) makes it relatively impervious to interference anyway (thats the
whole purpose of them), but to answer your question in detail you
need to provide the material you are using, the distance to the
reference plane, and find someone with a greater understanding
of physics (not me).

Also, Ultracad has a free crosstalk calculator if that helps.

good luck,
Jack





D Sharples <[log in to unmask]>@IPC.ORG>
5Jan2002 06:20 AM

Please respond to "(Designers Council Forum)" <[log in to unmask]>

Sent by:  DesignerCouncil <[log in to unmask]>



To:   [log in to unmask]
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Subject:  [DC] Impedence
Retain Until: 02/04/2002 Retention Category: G90 - Information and Reports
Caterpillar Confidential:  Green


Hi All,

I hope I am not to early in the new year for this one.
Please can anyone help.
How far apart and away from other tracks can I run differential pairs with
a
differential impedance of 150 ohm  @ 2gHz without interference.


Regards,

Dave Sharples
[log in to unmask]

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