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Fig. 8.16 Connection in Group Delay Measurement
3) Select the S21 measurement mode.
4) Select the settings corresponding to the tested device, including:
a) Format: phase.
b) Scale: automatic scale.
c) Number of measurement points: select the appropriate number to avoid insufficient sampling.
5) Remove and calibrate the tested device.
6) Reconnect the tested device.
7) Set the group delay display format and the scale of measurement display to realize the best observation effect.
8) Increase the aperture and reduce the noise on the trace by the smoothing function of the analyzer. At the same time, keep
meaningful details. Take the following steps to increase the aperture:
a) Enable the smoothing function of the analyzer.
b) Change the smoothing aperture (max. 25% of the frequency span).
9) Read the group delay of the relevant frequency through the marker.
10) Print or save the data.
8.6.
Absolute Output Power
The absolute output power is the relationship between the displayed absolute power (dBm or W) and frequency.
8.6.1.
What is the absolute output power?
The absolute output power is the power of the reception port of the analyzer. This is the absolute power, not based on the incident
power or source power (or the ratio). The value indicated on the longitudinal axis of the grid is in dBm in the logarithm amplitude
format. It is the power tested based on 1mW.
0dBm=1mW
-10dBm=0.1mW
+10dBm=10mW
The value indicated on the vertical axis of the grid in the logarithm amplitude format is in W.
8.6.2.
Why to measure the absolute output power?
If the absolute power instead of the relative power must be used as the amplifier output, the absolute output power must be measured.
In gain compression measurement, the absolution output power of the amplifier should be measured based on 1dB compression. In
order to improve the measurement accuracy, considerations must be given to the following factors:
