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these contributors have been propagated to the different amplifier
parameters characterised using a VNA. The following
results were obtained from our measurements:
◗ The uncertainty in return loss depends on the magnitude
of the reflection and can be accurately characterized using
S-parameters.
◗ The uncertainty in small-signal gain (S21) is around
0.03 dB.
◗ The uncertainty in large-signal gain is around 0.11 dB,
i.e., around 0.08 dB larger than the small-signal gain. This
shows that the uncertainty due to the power meter is the
dominant source of uncertainty in large-signal measurements.
The uncertainty in different types of amplifier gain
can be determined. For example, in our analysis, smallsignal,
large-signal, and power gains were considered.
◗ The uncertainty in input power depends on the input
reflection coefficient of the amplifier as is evident in the
increase in the uncertainties above 3 GHz.
◗ The uncertainty in power gain is around 0.03 dB larger
than the uncertainty in the input power.
◗ The uncertainty in the 1 dB gain compression point is
around 0.03 dB larger than the uncertainty in the power
gain.
The power meter uncertainty is a dominant factor in the
measurement uncertainty for large-signal parameters. The
manufacturer-supplied power meter uncertainty information
was used in our experiment. It is also possible to independently
characterize the power meter uncertainty and provide
this uncertainty information in VNA-DUO.
Summary and Conclusions
Methods to quantify the measurement uncertainties associated
with some basic parameters characterizing the linear and
non-linear operation of an amplifier have been presented in
this paper. These methods have been applied to measurements
of several amplifiers and results have been presented here for
one of these amplifiers. A similar methodology could be deployed
to analyze other amplifier parameters.
A VNA can be used to characterize parameters such as return
losses, small-signal gain, input power, output power,
large-signal gain, 1 dB compression point, etc. which describe
the small-signal and large-signal behavior of an amplifier. To
characterize the large-signal parameters, an extra step involving
a power meter is required in the calibration of the VNA.
This paper has shown that VNA-DUO can be used to provide
an estimate of the uncertainty in these amplifier parameters.
The uncertainty in the large-signal parameters were found to
be larger than the uncertainty in the small-signal parameters
and this is mainly due to the uncertainty in the power meter
used to calibrate the VNA for large-signal measurements.
Acknowledgment
The work described in this paper was partially funded by
the UK Government's National Measurement System (NMS)
program, partially funded through the European Metrology
Programme for Innovation and Research (EMPIR) project
September 2022
16ENG06 Metrology for advanced energy-saving technology in the
next-generation electronic applications, and partially funded by
EMPIR project 20IND03 RF Measurements for future communications
applications. The EMPIR is jointly funded by the EMPIR
participating countries within EURAMET and the European
Union.
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IEEE Instrumentation & Measurement Magazine
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