RE: [SI-LIST] : Transmission line model in Pspice

Tan, Chun Chiat (chun.chiat.tan@intel.com)
Sun, 17 May 1998 18:05:00 -0700

Hamid,

As most engineers would recommend, the "High Speed Digital Design" by
Dr. Howard Johnson & Dr. Martin Graham would be the first reference. The
MathCAD formulae at the end of the book should be useful to use. If you
have MathCAD, downloading those files from Internet to perform the
calculation would save you time. Refer to
http://www.sigcon.com/design.htm

Of course, best if you can access any simulator to perform field
simulation to derive at the result. Previously I have found some slight
differences when comparing to Ansoft parameter extractors. Believe those
formulae would still be a good start.

Some precaution that one has to bear in mind:
1)for microstrip, the formulae applied to trace with copper expose to
the air. This is not exactly the case in real life PCB as there would be
soldermask etc covering up the copper making it a coated microstrip. In
this case, best to use field simulator to solve.
2)if there are many traces concentrate at any place, then calculated
(ideal single trace case) may not reflect the actual application.

Regards,
Chun Chiat
iTTO Penang
Intel Technology (M) Sdn. Bhd.

______________________________ Reply Separator
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Subject: [SI-LIST] : Transmission line model in Pspice
Author: "Hamid Kharrati" [SMTP:hamid@isidesign.com] at MSXGATE
Date: 5/16/98 5:45 AM

I am using Pspice to simulate PCB traces. The lossy models require R, L, G,
and C values. Are there handbooks (or formulas) where I can figure out
these values based on the PCB/Trace characteristics? Any help is
appreciated.

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