There is a large body of free information on the UltraCAD website:
http://www.ultracad.com/homepage.htm
that deals with trace impedance and other layout issues.  They also have
several free calculator programs, including one to verify or aid impedance -
vs. - geometry tradeoffs.  Try it . . . you'll like it!


Carl Van Wormer
Cipher Systems
1815 NW 169th Place, Suite 5010
Beaverton, OR  97006
Phone (503)-617-7447    Fax (503)-617-6550

 -----Original Message-----
From:   Earl Moon [mailto:[log in to unmask]]
Sent:   Friday, November 30, 2001 7:07 AM
To:     [log in to unmask]
Subject:        Re: [TN] Fw: Differential impedance

I know you remember the classic definition of microstrip as a function of
surface traces referenced only to one internal plane - either exposed to air
or buried by solder mask. Likewise, stripline is a function of traces
between two reference planes either centered or offset. Don't know what
difference continuous or split planes make to these definitions but for
possible functionality and performance factors.

MoonMan

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