The typical procedure for a noise figure measurement is listed below.
1. It is assumed that the user has already acquired non-compressed DUT gain data and has it available in an S2P file.
2. It is assumed the user has performed a composite receiver calibration.
• See the VectorStar MS4640A Measurement and Calibration Guide – 10410-00269 for more information about a noise figure measurement composite receiver.
Change the Instrument Mode to Noise Figure
3. On the APPLICATION menu, select the Noise Figure button.
• A notice dialog box advises about saving the current instrument setup so it can be recalled at a later time.
• When Continue is selected, the instrument changes application modes to Noise Figure.
• The NF Setup (Noise Figure Setup) menu appears.
• The instrument resets the default settings for noise figure trace condition to a single trace and Noise Figure (LogMag) response.
4. On the NF SETUP menu, select Noise Figure Configuration.
• The NF CONFIG (Noise Figure Configuration) menu appears.
Set the Noise Figure Measurement Configuration
5. On the NF CONFIG menu, select the configuration parameters for the noise figure measurement:
• Frequency Start
• Frequency Stop
• Number of Sweep Points
• CW ON/OFF
• CW Frequency
• Number of RMS Points
• Intermediate Frequency Bandwidth
Get the DUT S-Parameter Data
6. Go back and get the DUT S-Parameter data.
7. Return to the NF SETUP menu by selecting the back icon at the bottom of the menu.
• The NF SETUP menu appears.
8. On the NF SETUP menu, select Get DUT S-Param Data.
• The DUT S-PARAM DATA dialog box appears.
• Navigate to the stored data and open the file.
Get the Receiver Calibration Data
9. Go back and recall the Receiver Calibration file.
10. On the NF SETUP menu, select Recall Receiver Calibration.
• The RECALL RECEIVER CALIBRATION dialog box appears.
• Navigate to the stored data and open the file.
Perform the Noise Calibration.
11. Insert the DUT with the cold source on input.
12. The trace display shows Log magnitude noise figure versus frequency.
13. When all noise figure measurements are complete, on the APPLICATION menu, select the Transmission/Reflection button.
• A notice dialog box advises about saving the current instrument setup so it can be recalled at a later time.
• When Continue is selected, the instrument changes application modes to Transmission/Reflection and the Noise Figure Setup button becomes unavailable.
• The instrument resets the factory as-shipped default settings for transmission/reflection which are four traces as:
• S11 response on a Smith Chart trace display
• S12 response on dual LogMag + Phase trace display
• S21 response on dual LogMag + Phase trace display
• S22 response on a Smith Chart trace display
14. If a prior preset was in effect, it can be recalled using the RECALL SETUP dialog box located at MENU BAR | File | Recall Setup | RECALL SETUP Dialog Box.
Primary Application Menus and Noise Figure Dialogs and Menus
The primary menu and dialog set for noise figure measurement on the APPLICATION menu, the NF SETUP menu, and the related dialog boxes is shown below. After clearing the entry T/R to NF dialog box, the NF SETUP menu appears. When changing from NF to T/R, a similar exit dialog box appears, and when cleared, resolves into the APPLICATION menu in Transmission/Reflection mode.
APPLICATION Menu and NF SETUP Menu and Dialog Set
1. APPLICATION Menu – Transmission/Reflection Mode – Typical APPLICATION menu variant with Option 041 equipped on VNA.
2. NOISE FIGURE MEASUREMENT Mode Change Dialog Box – Provides options for canceling or saving setup and proceeding by selecting Continue.
3. APPLICATION Menu – Noise Figure mode selected on typical menu variant.
4. NF SETUP Menu – After APPLICATION menu Noise Figure Setup button is selected.
5. To exit Noise Figure Mode, select the Transmission/Reflection button on the APPLICATION menu.
7. APPLICATION Menu – Transmission/Reflection Mode.
Transmission/Reflection Mode to Noise Figure Mode
When the APPLICATION menu is set to Transmission/Reflection application mode and Noise Figure mode is selected, the NOISE FIGURE MEASUREMENT dialog box appears. The dialog provides opportunities to:
• Cancel out of the change to Noise Figure application mode, and remain in Transmission/Reflection application mode.
• Save the current instrument setup as an Active Channel Setup and Calibration CHX file and then either Cancel (above) or proceed (below).
• Continue into Noise Figure application mode.
Noise Figure Mode to Transmission/Reflection Mode
Similarly, when the APPLICATION menu is set Noise Figure application mode, and Transmission/Reflection application mode is selected, the TRANSMISSION REFLECTION MEASUREMENT dialog box appears. The dialog provides the opportunities to:
• Cancel out of the change to Transmission/Reflection application mode and remain in Noise Figure application mode.
• Save the current instrument setup as an Active Channel Setup and Calibration CHX file and then either Cancel (above) or proceed (below).
• Continue into Transmission/Reflection application mode.
