Noise Figure Measurements Option (K30) R&S FSL
1300.2519.12 2.106 E-11
M
easurement on a mixer with an average sideband suppression
freq.
LORFIFImage
4dB
For measurements on a mixer with a low image–frequency rejection, a measuring error of 0 to 3 dB is
obtained if the image–frequency rejection is not taken into account. In this case, set the image rejection
in the Frequency Settings dialog box to 4 dB to produce the correct results.
Measurement on a mixer with unknown sideband suppression
freq.
LORFIFImage
X dB
If the image rejection is not known, accurate noise results can still be produced. However, the gain of
the DUT must be known and an additional filter is required.
Test setup
Fig. 2-76: Preparation for calibration
Fig. 2-77: Test setup for the main measurement
In this test setup, a low pass filter prevents noise from the noise source from being fed in at the image
frequency. Depending on the position of the frequency bands, a highpass or bandpass filter may also
be necessary for the RF frequency instead of the lowpass filter. The important point is that noise from
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