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[SI-LIST] Re: PureMode VNA vs 4port VNA

From: dgun@xxxxxxxxxx
To: si-list@xxxxxxxxxxxxx
Date: Sat, 09 Apr 2005 20:02:08 -0800

If you are trying to characterize a system in it's non-linear region,
you need more information than just s-parameters.  Even, so-called
"large-signal" s-parameters will not be adequate.

This doesn't mean the measurements aren't useful--just that they aren't
generally applicable.

There is a lot of work going on to develop robust measurement-based
models of general non-linear systems. Finding the correct stimulus
is a key factor for a successful model (and then being able to
measure it!). The correct stimulus will elicit a response from the
system that can be used to create a general non-linear model. This
general model will then be able to accurately predict the response for
any arbitrary stimulus. Not an easy task.

I think it will require a new class of instrument different from either
a pure-mode or a 4-port VNA.

--
Daniel

From: "Loyer, Jeff" <jeff.loyer@xxxxxxxxx>
>=20
> Hi Pat (and others),
> Maybe I'm having a temporary brain misfire here, but doesn't the
> argument of using a "pure-mode" differential VNA for non-linear systems
> imply that the excitation of the differential VNA has to be a voltage
> representative of the actual range under consideration?
>=20
> I.E., it seems not merely enough to be "pure-mode"; the voltage swing
> must also be modified/controlled. This would also seem to be true for
> measuring any non-linear system, including 2-port measurements, and
> TDR/TDT.
>=20
> If I'm not missing something, how do you solve characterizing and
> building measurement-based models with this added complexity (transfer
> as a function of frequency and voltage)?

--=20
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[SI-LIST] Re: PureMode VNA vs 4port VNA

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