# RE: [SI-LIST] : Common/Differential-Mode Impedance versus frequency

From: Jian Zheng ([email protected])
Date: Thu Apr 27 2000 - 11:14:44 PDT

Hi, Allen:

There are multiple ways to find the even mode and odd mode parameters
depending upon what you get:

(1) If you have the obtained the L11, L12, R11, C11, C12 and G11 for the
unit length of your coupled transmission line, you can get:

Zodd = SQRT{ [ jOmega*(L11-L12)+R11 ] / [ jOmega*(C11+2*C12) + G11 ] }
Zeven = SQRT{ [ jOmega*(L11+L12)+R12 ] / [ jOmega*C11 + G11 ] }

(2) If you get the 4-port s-parameters (y- or z-parameters), the derivation
for Zodd and Zeven can be quite tedious. You may try to extract the LRCG
from the 4-port s-parameters first. We do have utility programs to extract
the LRCG for you or to get the Zodd and Zeven and all the other parameters
for the transmission line under odd or even modes. However, it is part of a
me know. Thanks!

Best regards,

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Jian-X. Zheng, Ph.D
Zeland Software, Inc., 39676 Mission Blvd., Fremont, CA 94539, U.S.A.
Tel: 510-797-8109, Fax: 510-797-8241, Web: http://www.zeland.com
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> -----Original Message-----
> From: [email protected]
> [mailto:[email protected]]On Behalf Of Allen Fernandez
> Sent: Thursday, April 27, 2000 8:30 AM
> To: '[email protected]'
> Subject: [SI-LIST] : Common/Differential-Mode Impedance versus frequency
>
>
> Hello Folks,
>
> I am trying to set-up a coupled microstrip line simulation (using
> HP-EEsof's
> ADS) so I can see the
> effects of its common-mode and differential-mode characteristic impedances
> as a function of frequency.
> I plan on using the coupled microstrip model that is included in ADS's
> standard model library.
>
> Can anyone recommend a method to do this ? Or suggest a paper that will
> explain how to do this ?
>
> Thanks,
>
> Allen S. Fernandez
> Project Engineer - Jabil Circuit Design Services
> 9424 N.International Ct.
> St.Petersburg, FL 33716
> (727) 803-3941
>
>
>
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