Marketing and System Development
TDA Systems, Inc.
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Portland, OR 97223
The Interconnect Modeling Company(tm)
From: fabrizio zanella =
Sent: Wednesday, November 11, 1998 4:04 PM
Subject: [SI-LIST] : Differential impedance
To calculate the differential impedance of a transmission line pair, =
1) Zdiff =3D 2 * Zoo, where Zoo is the odd mode impedance of the pair. =
formula is used by the pc board manufacturers.
I was speaking to someone last week who has 30+ years in the industry =
said this formula is wrong, that the real differential impedance should =
2) Zdiff =3D square root of (Zoo * Zee), where Zee is the even mode=20
If I compare 1) to 2), I get quite different values of differential=20
impedance. Does anyone have comments on this? =20
Thanks, Fabrizio Zanella
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