428
Keysight EXG and MXG X-Series Signal Generators User’s Guide
Troubleshooting
RF Output
The solution at right shows a
similar configuration with the
addition of a 10 dB attenuator
connected between the RF output
of the signal generator and the
input of the mixer. The signal
generator’s ALC level increases to
+2 dBm and transmits through a
10 dB attenuator to achieve the
required –8 dBm amplitude at the
mixer input.
Compared to the original
configuration, the ALC level is 10
dB higher while the attenuator
reduces the LO feedthrough (and
the signal generator’s RF output) by 10 dB. Using the attenuated configuration, the detector is
exposed to a +2 dBm desired signal versus the
–15 dBm undesired LO feedthrough. This 17 dB difference between desired and undesired energy
results in a maximum 0.1 dB shift in the signal generator’s RF output level.
Mixer
LO
ALC Level/
RF Output
=
+
2 dBm
RF
Level
Signal Generator
Output Control
Detector
measures
+
2 dBm
ALC level
Detector
measures
−
15 dBm
reverse
power
LO
Feedthru
=
−
5 dBm
RF
Output
=
−
8
LO Level
=
+10
dBm
IF
Reverse Power Solution
10 dB
ATTEN
