Rohde&Schwarz R&S®ZVA, R&S®ZVT Application Sheets Application Sheet

&S ZVA / R&S ZVT True Differential Mode

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differ from the default settings. A subsequent source power calibration is recommended.

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Test Setup and Preparations

True Differential Mode

This application sheet describes the use of option R&S ZVA-K6, True Differential
Mode, on R&S ZVA or R&S ZVT vector network analyzers. In this mode, the analyzers
can generate true differential and common mode stimuli at arbitrary reference planes in
the test setup and determine mixed-mode S-parameters, wave quantities and ratios.
The true differential mode is suitable for testing nonlinear balanced devices under real
operating conditions.

Test Setup and Preparations

The true differential mode requires a port configuration with at least one balanced port.
In the following we use a four-port network analyzer to measure a 2-port DUT with
balanced input and balanced output.

Calibration and stimulus power

A consistent system error correction is essential for accurate balanced waves at the
reference planes and accurate measurement results. You should always perform a full
n-port calibration (TOSM, UOSM or one of the Txx calibration types) of all physical p
involved in the true differential measurement and change the port impedances, if they

Note that the power setting of a true differential source refers to the differential and
common modes directly.

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&S ZVA / R&S ZVT True Differential Mode

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Measuring Balanced S-Parameters

Measuring Balanced S-Parameters

The following example shows how to activate the true differential mode in order to
obtain mixed-mode S-parameters for the test setup shown above.

1. Perform a full calibration of all four analyzer ports, preferably using a calibration
nit for automatic (TOSM) calibration.

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2. Preferably, perform a source power calibration at the input of your DUT.

3. Click “Trace > Measure > More S-Params...”.

4. In the “Port Configuration” panel of the “More S-Parameters” dialog opened, click

“Balanced and Measured Ports”.

5. In the “Predefined Configs” tab of the “Balanced and Measured Ports” dialog

opened, select the port configuration that is suitable for your DUT.

Allowed port combinations

The true differential mode requires logical port combinations with independent power
sources. Do not use ports 1/2 or ports 3/4 to create a logical port.

6. Still in the “Predefined Configs” tab, enable “True Differential Mode”.

7. Open the “Def Balanced Port” tab and assign the appropriate differential and

common mode reference impedances to both logical ports.

8. Click “OK” to close the “Balanced and Measured Ports” dialog.

9. Connect one balanced port of your DUT to ports 1 and 3 of the network analyzer,

the other balanced port of your DUT to ports 2 and 4 of the network analyzer, in
accordance with the selected port combination and reference impedances.

10. Back in the “More S-Parameters” dialog, select the mixed-mode S-parameter that

you wish to measure.

11. Click OK to close the “More S-Parameters” dialog and observe the measurement

result in the diagram area.

Measurement Wizard

You can also access all the described settings from the „Measurement Wizard“.
You can also use the calibration wizard for step no. 1, e.g. if you want to use one of the
7-term calibration types (TNA, TRL, ...).

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