[SI-LIST] Re: si-list Digest V7 #326

From: "Dmitriev-Zdorov, Vladimir" <vladimir_dmitriev-zdorov@xxxxxxxxxx>
To: <si-list@xxxxxxxxxxxxx>
Date: Mon, 1 Oct 2007 08:46:36 -0700

Hi Jeff,

Excuse me for jumping in. It just happened to me recently to refresh my
memory about the relation between S parameters and "voltage transfer
ratio", VTR, (where the latter I think is the ratio of the voltage
across the load to the voltage on the input voltage source, in AC mode).

Actually, VTR is completely defined by S21 if:

- S-parameters were measured for the entire 2-port where the 1-st port
is to attach the source and the 2-nd port is for load;
- the source's internal impedance and the load's impedance are equal the
corresponding S-parameter reference impedances (these two are often
equal but this is not necessary)

If either of these two conditions isn't true, S21 and VTR are not
related with a factor 0.5 (VTR # 0.5*S12)

Vladimir

-----Original Message-----
From: FreeLists Mailing List Manager [mailto:ecartis@xxxxxxxxxxxxx]=20
Sent: Sunday, September 30, 2007 9:21 PM
To: si-list digest users
Subject: si-list Digest V7 #326

Subject: [SI-LIST] Re: AC Coupled Signals
Date: Sun, 30 Sep 2007 19:47:54 -0700
From: "Loyer, Jeff" <jeff.loyer@xxxxxxxxx>

Hi Istvan,
Could you point me towards more information on the "voltage transfer
ratio", and the difference between it and s21/s12?  When I did the pulse
response of a system where S21 =3D3D S12 (though S11 and S22 were very
different, and the reflections were significant), it came out equal (p21
=3D3D p12, see my posting of 9/15).  Thus, I think the eye diagram will =
=3D
come
out equal if S21 =3D3D S12.  =3D20

Thanks,
Jeff Loyer


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[SI-LIST] Re: si-list Digest V7 #326

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