R&S ZVL
GUI Reference
Channel Menu
Operating Manual 1303.6580.32-06
231
Auto Offset
Determines all offset parameters such that the residual group delay of the active trace (defined as the
negative derivative of the phase response) is minimized and the measured loss is minimized as far as
possible across the entire sweep range.
Auto Offset
involves a two-step procedure:
•
An
Auto Length
correction modifies the phase of the measured quantity, minimizing the residual
group delay. The magnitude of the measured quantity is not affected.
•
The auto loss correction modifies the magnitude of the measured quantity, leaving the (auto
length-corrected) phase unchanged.
Preconditions for Auto Offset, effect on measured quantities and exceptions
Auto Offset
is enabled if the measured quantity contains the necessary phase information as a
function of the frequency, and if the interpretation of the results is unambiguous:
•
A frequency sweep must be active.
•
The measured quantity must be an S-parameter, a converted impedance or a converted
admittance.
The effect of
Auto Offset
on S-parameters is to eliminate a linear phase response and account for a
loss as described above. Converted admittances or impedances are calculated from the
corresponding
Auto Offset
corrected S-parameters. Stability factors are not derived from a single S-
parameter, therefore
Auto Offset
is disabled.
Calculation of loss parameters
The loss is assumed to be given in terms of the DC loss Loss
DC
, the reference frequency f
ref
, and
the loss at the reference frequency Loss(f
ref
). The formula used in the
Auto Loss
algorithm is similar
to the formula for manual entry of the loss parameters (see
Loss parameters: Definition).
The result
is calculated according to the following rules:
•
The reference frequency f
ref
is kept at its previously defined value (default: 1 GHz).
•
The DC loss c is zero except for S-parameters with maximum dB magnitude larger than –
0.01 dB.
•
Auto Offset for S-parameters centers the corrected dB magnitude as close as possible
around 0 dB.
The resulting offset parameters are displayed in the
Electrical Length, Mechanical Length,
and
Delay
dialogs.
Remote control:
[SENSe<Ch>:]CORRection:LOSS<port_no>:AUTO ONCE
Deembedding and Embedding
The
Embedding...
and
Deembedding...
dialogs
define virtual networks (transformation networks) to be
added to/removed from the measurement circuit for a DUT.
Embedding a DUT into a matching network
To be integrated in application circuits, high-impedance components like Surface Acoustic Wave (SAW)
filters are often combined with a matching network. To obtain the characteristics of a component with an
added matching network, both must be integrated in the measurement circuit of the network analyzer. The
figure below shows a 2-port DUT that is combined with a real matching circuit consisting of a serial
capacitor and a shunt inductor.
