Concepts and features
R&S
®
ZND
176
User Manual 1173.9557.02 ─ 61
Table 4-13: System error correction and power calibration for various measurements
Measurement
System error correction
Scalar power calibration
S-parameter meas. on linear
DUTs
Yes, necessary
Not necessary
Meas. of wave quantities or ratios
on linear or non-linear DUTs
Yes, recommended
a-wave: power (source) neces-
sary
b-wave: meas. receiver necessary
Power sweep, e.g. for compres-
sion point measurement
Yes, necessary
Power (source): necessary
Meas. receiver: not necessary
In general, a power calibration involves two stages:
1.
Source power calibration:
An external power meter is connected to the calibra-
tion plane. The analyzer uses the power meter readings to calibrate its reference
receiver. Subsequently, it modifies its source power so that the calibrated reference
receiver reading corresponds to the desired source power value (flatness calibra-
tion).
Tip:
Since version 3.0 of the analyzer firmware, it is possible to perform the source
(flatness) calibration using the power meter (without previously calibrating the refer-
ence receiver).
2.
Measurement receiver calibration:
The analyzer uses the calibrated source sig-
nal to adjust the power reading at the receive port.
4.5.6.1
Source power calibration
A source power calibration ensures accurate power levels of the generated waves at
an arbitrary calibration plane in the measurement path. Typically the calibration plane
corresponds to the input of the DUT.
In a frequency sweep, the power at the calibration plane is maintained at a constant
"Cal Power" value. The source power calibration eliminates frequency response errors
in the signal path between the source and the calibration plane. It is possible to intro-
duce an arbitrary attenuation or gain into the signal path so that the cal power is not
restricted to the power range of the source. A typical application for a power calibration
in a frequency sweep is the measurement of the gain of an amplifier across a fre-
quency range but at a fixed input power.
In a power sweep, the power calibration ensures that the power at the calibration plane
is either constant or a linear function of the stimulus power. A typical application for a
power calibration in a power sweep is the measurement of the gain of an amplifier
across a power range but at a fixed frequency. The correction data acquired in a fre-
quency or power sweep is re-used if a "Time" or "CW Mode" sweep is activated.
Calibration procedure
The source power calibration requires an external power meter, to be connected via
GPIB bus, USB or LAN interface. The power sensor can be connected directly at the
Calibration
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