My rules of thumb:

Spacing between lines, 2 x trace width.(Trace width determined by impedance)
Spacing between pairs, 4 x trace width.
Avoid stubs
Place in-line series resistors at the source.
Terminations belong at the destination.
Follow the above rules, and trace length and layer changes will have minimal
effect.

BTW, I'm hand routing about 60 differential pairs on my current design,
involving video, audio and ethernet pairs.

David Ricketts

Pertek Engineering
Voice: 949-475-4485
Fax:   949-475-4493

mailto:[log in to unmask]

http://www.PertekEngineering.com



-----Original Message-----
From: DesignerCouncil [mailto:[log in to unmask]]On Behalf Of
Konrad Iten
Sent: Tuesday, October 31, 2000 9:04 AM
To: [log in to unmask]
Subject: [DC] diff pair routing


Hi

Could some please give me some info about diff. pair rounting.
Is it ok to have layer changes ? How about spacing, trace widths and via
count ?
Stubs, source and termination ??

I guess what I'm looking for are some basic rules for Diff. pair rounting.

Thanks everyone for taking the time to answer my questions.

Much appreciated

 Konrad

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