Just a guess... but the old TV antenna 'twin lead' was 300 ohm impedance...
maybe they want a differential impedance between two lines on the board
rather than an impedance with respect to a ground plane like micro strip
does ???

Bill Brooks - KG6VVP
PCB Design Engineer , C.I.D.+, C.I.I.
Tel: (760)597-1500 Ext 3772 Fax: (760)597-1510
e-mail:[log in to unmask]
http://www.dtwc.com
http://pcbwizards.com

-----Original Message-----
From: Mcmaster, Michael [mailto:[log in to unmask]]
Sent: Friday, April 15, 2005 2:37 PM
To: [log in to unmask]
Subject: Re: [TN] impedance value very high

I ran this through our field solver.  For a 1 mil trace, you'd need a
dielectric thickness of about 5 inches to do this.

Thick as a brick.

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Eric Bonatti
Sent: Friday, April 15, 2005 10:28 AM
To: [log in to unmask]
Subject: [TN] impedance value very high

I have a puzzling question for you impedance experts:

A customer is asking for a PCB characteristic impedance for a single
trace to be 332 Ohms +/- 5%.

I've never seen a requirement for an impedance to be this high.  Has
anyone here seen this before?  HyperLynx is choking on this.

Thank you in advance for your input, it is greatly appreciated.


Eric Bonatti, C.I.D.
PCB Designer
StrataFLEX  Corporation
Tel.: +1.416.752.2224 xt.227
Fax: +1.416.752.6719
Toll Free: +1.866.771.7765
E-mail: [log in to unmask]
Web: www.strataflex.com

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