Rohde & Schwarz R&S FSL3 - Duts with very Large Gain

R&S FSL Noise Figure Measurements Option (K30)
1300.2519.12 2.103 E-11
4. Start
the calibration for the Noise Figure Measurements option.

Press the SWEEP key.
 Press the Cal softkey.
The progress bar indicates the progress of the calibration measurement. After successful
calibration, in the status bar, a corresponding message is displayed and the title bar at the top of
the screen shows the status on the right–hand–side.
Performing the main measurement
1. Insert the DUT (in this example, the amplifier) into the test setup between the noise source and RF
input of the R&S FSL (see Fig. 2-74).
Fig. 2-74: Test setup for the main measurement
2. To select the sweep mode, press the SWEEP key.
3. Press the RUN key to start the measurement.
Measurement results are updated as the measurement is in progress. The results are displayed in
graphical form. There are two traces, one for noise figure/temperature and one for the gain of the
DUT.
4. To change the display from the graphical form to a tabular list of measurement points, press the
Display List/Graph softkey.
Note: If a measurement is started while another measurement is still in progress, the first
measurement is aborted and the new measurement started immediately.
DUTs with very Large Gain
If the gain of the DUT exceeds 60 dB, the total gain must be reduced by an external attenuator. The
total gain of the DUT together with the external attenuator should lie within the range from 10 dB to
60 dB. A total gain of 20 dB to 30 dB is recommended. For a DUT with a gain of e.g. 64 dB, it is
recommended to use an external 40 dB–attenuator.
If an external attenuator is used, in the Measurement Settings dialog box, the entry in the Range field
should be modified according to the total gain ( = G
DUT
– external attenuator).
The attenuation values of the external attenuator are entered in the Loss Settings dialog box under
Loss Output Settings.
Inaccuracies when entering this attenuation mainly influence the measured gain. The noise figure
remains to a large extent unaffected.