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Reply To: | TechNet E-Mail Forum. |
Date: | Wed, 14 Aug 2002 10:47:05 -0700 |
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Wes,
Try www.ideaconsulting.com. They have some on-line impedance calculation
pages.
IPC-2141 has some simple formulas and the specification for TDR (time domain
reflectrometry) impedance measusrments. It also specifies the standard
impedance test coupon for the PCB.
Johnson & Graham "High-Speed Digital Design" has chapter on transmission
line and formulas in appendix C. I've cast these into C programs which I can
give you. (contact me off line.)
National Semiconductor's app note AP-905 shows some formulas for
differential impedance which are reportedly widely used but can have as much
as +/-10% error.
I am now using Hyperlynx which is an expensive ($20K+) package which
proports to use field equations (I assume Maxwell's) to calculate impedance
directly from the trace geometry and PCB bulk parameters.
Ray Klein
-----Original Message-----
From: Malewicz Wesley [mailto:[log in to unmask]]
Sent: Wednesday, August 14, 2002 8:04 AM
To: [log in to unmask]
Subject: [TN] Designing for Impedance Control
Importance: High
Hi,
Does any one have a good source as to where a test engineer can go for a
crash course on designing for Impedance Control for tester PCB's.
Thanking you in-advance for any information.
Wes
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