System Overview
R&S
®
ZVA
82
Quick Start Guide 1145.1090.62 ─ 10
3.3.2.11
Unbalance-Balance Conversion
Unbalance-balance conversion is the simulation of one or more unbalance-balance
transformers (baluns) integrated in the measurement circuit in order to convert the DUT
ports from an unbalanced state into a balanced state and virtually separate the differential
and common mode signals. The analyzer measures the unbalanced state but converts
the results and calculates mixed mode parameters, e.g. mixed mode S-parameters. No
physical transformer is needed.
With option R&S ZVA-K6, True Differential Mode, the analyzer can generate balanced
waves at arbitrary reference planes in the test setup and determine balanced results such
as S-parameters, wave quantities and ratios. The true differential mode also provides two
additional sweep types, the "amplitude imbalance" and "phase imbalance" sweeps. What
is said below is valid for both the simulated balanced mode and the true differential mode.
To perform balanced measurements, a pair of physical analyzer ports is combined to
form a logical port. The balanced port of the DUT is directly connected to the analyzer
ports
Unbalance-balance conversion avoids the disadvantages of real transformers:
●
There is no need to fabricate test fixtures with integrated baluns for each type of DUT.
●
The measurement is not impaired by the non-ideal characteristics of the balun (e.g.
error tolerances, limited frequency range).
●
Calibration can be performed at the DUT's ports. If necessary (e.g. to compensate
for the effect of a test fixture), it is possible to shift the calibration plane using length
offset parameters.
●
Differential and common mode parameters can be evaluated with a single test setup.
3.3.2.12
Balanced Port Configurations
Defining a logical ports requires two physical analyzer ports. The ports of an analyzer are
equivalent and can be freely combined. Moreover, it is possible to assign arbitrary, inde-
pendent reference impedance values to each unbalanced port and to the differential and
Measured Quantities
