Thanks,
-Dima
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D
Dima Smolyansky
Marketing and System Development
TDA Systems, Inc.
7465 SW Elmwood St.
Portland, OR 97223
(503) 977-3629
(503) 245-5684
dima@tdasystems.com
http://www.tdasystems.com
The Interconnect Modeling Company(tm)
-----Original Message-----
From: fabrizio zanella =
[SMTP:fabrizio=3Dzanella%eng%emchop1@fishbowl02.lss.emc.com]
Sent: Wednesday, November 11, 1998 4:04 PM
To: si-list@silab.Eng.Sun.COM
Subject: [SI-LIST] : Differential impedance
To calculate the differential impedance of a transmission line pair, =
I've=20
always used=20
1) Zdiff =3D 2 * Zoo, where Zoo is the odd mode impedance of the pair. =
This=20
formula is used by the pc board manufacturers.
I was speaking to someone last week who has 30+ years in the industry =
and=20
said this formula is wrong, that the real differential impedance should =
be=20
calculated as
2) Zdiff =3D square root of (Zoo * Zee), where Zee is the even mode=20
impedance. =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
EMC corporation
fzanella@emc.com
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