Concepts and Features
R&S
®
ZNA
212
User Manual 1178.6462.02 ─ 12
The source ports and the properties of the coherent signals are all defined in the
"Source Coherence" dialog. After a system error correction, the coherent signals with
the selected properties are available at the calibrated reference plane.
Prerequisites for accurate phase control
●
Defined Coherence mode relies on wave correction. A consistent system error cor-
rection is essential for accurate coherent waves at the reference planes. You
should always perform a full n-port calibration (TOSM, UOSM or one of the Txx cal-
ibration types) of all physical ports involved and change the reference impedances,
if they differ from the default settings. A subsequent source power calibration is
recommended.
The system error correction applies to all a- and b-waves of the n calibrated ports,
not only to waves with a defined phase. You can also use offset parameters in
order to move the reference plane where the analyzer provides an accurate coher-
ent signal.
●
The defined phases are established during a pre measurement per sweep point
and source coherent port, which significantly slows down the sweep.
5.7.5
True Differential Mode
Option R&S
ZNA-K61
Differential transmission lines and circuits are widely used, because their characteris-
tics give them a lower susceptibility to electromagnetic interference. Linear balanced
devices can be tested with sufficient accuracy using the
, where
the vector network analyzer generates unbalanced stimulus signals and uses a mathe-
matical transformation to convert unbalanced wave quantities into balanced S-parame-
ters. A different behavior is expected for nonlinear balanced devices, where the trans-
mission characteristics of the DUT may depend on how closely the stimulus signal
matches real operating conditions.
In
true differential mode
, a four-port R&S
ZNA generates true differential and common
mode stimuli at arbitrary reference planes in the test setup and determines mixed-
mode S-parameters, wave quantities and ratios. It is also possible to perform true dif-
ferential measurements on
or to use true differential mode
in combination with external frequency converters. Moreover the true differential mode
provides two additional sweep types, the
Amplitude Imbalance and Phase Imbalance
Optional Extensions and Accessories
