Keysight Technologies CXA N9000B, Manual

Page: 53 / 88

N9069C Noise Figure Measurement Guide 53
Measurement Related Tasks and Concepts
Setting the Measurement System
Figure 3-2 Single Sideband Mixer Measurements
Figure 3-2 shows an SSB mixer measurement (Downconverter, LSB) where a
filter makes it single sideband. If the IF frequency is lowered, the analyzer is
tuned to a lower frequency, and the USB and LSB bands will move closer to
the LO frequency. This makes filtering more difficult. If the IF is lowered further,
a point is reached where filtering is not possible and SSB measurements
cannot be made. The width of the filter limits where the LO or IF frequencies
sweep to make a measurement.
The analyzer performs frequency calculations and controls the frequency for a
variety of mixer modes. However, you have to determine the filter
requirements, and provide those filters in the measurement setup.
‘Downconverter’ means that the output frequency, (IF) is lower than the input,
(RF).
‘Upconverter’ means that the output frequency, (IF) is higher than the input
(RF).
The analyzer can handle SSB mixer measurements in modes defined by the
following combinational choices:
— DUT : Upconverter, Downconverter , or Amplifier with System
Downconverter On .
— Sideband : LSB or USB .
X-Series Input
LSB Input
USB Input
Amplitude
Frequency
F
LO
Band
F
lo
-F
lsb
mixing
Depending on F
lo
, a DUT
output filter may be needed
to reject LO leakage
Noise reaching mixer from
the DUT Input filter
(Filtered)
This is the convention used in this analyzer. Some engineering terms use
reversed terms for upconverters.