Dear Technetters,

Many designers and PCB fabricators ask me why differential traces often
measure higher impedances than predicted.

The following new application note explains how the physical characteristics
of woven glass reinforced substrates cause this to happen. And, how you can
help
minimize the differences between your calculations and the finished board.

http://www.polarinstruments.com/support/cits/AP139.html

I am sure you will find this note helps explain some of
the underlying reasons why sometimes the measured values
of impedance vary from the theoretical.

Hope this is of interest

Kind regards
Martyn Gaudion
www.polarinstruments.com

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