Hello Steve!

it is possible to design the impedance of a coplanar differential pair
without ground reference.
Brian Wadells "Transmission Line Design Handbook", ISBN 0-89006-436-9 covers
this. The impedance calculator of Polar Instruments www.polarinstruments.com
may be helpful too. Another valuable source of information is the si-list
(Signal Integrity) on Yahoo.

Regards
Thomas

> -----Original Message-----
> From: Steve Kelly [mailto:[log in to unmask]]
> Sent: Wednesday, March 03, 2004 8:53 PM
> Subject: Impedance design question
>
>
> Good day to all,
>
> I have been asked by a customer to design a single layer 100 ohm
> differential pair circuit. I realize the impedance may be
> highly variable
> but I do not know how to do the calculation when there is
> only one layer of
> copper. If I assume there is a ground line next to the
> differential pair do
> I use this as the reference? Any advice or help would be
> appreciated. Thanks
> in advance. Steve Kelly
>
>
>
> PFC Flexible Circuits Limited
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>
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>
>
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