Use a PXIe-5653 as an LO Source to PXIe-5831

Updated Jul 27, 2021

The following article describes how to setup, configure, and execute software to enable the PXIe-5831 to be used with an external local oscillator (LO) to improve RF performance.  The 5831 can be configured in a variety of ways, however in the this article we will focus on Configuration 1:
Configuration 1:  PXIe-5820, PXIe-3622, and PXIe-5653
Configuration 2:  PXIe-5820 and PXIe-3622
Configuration 3:  PXIe-5820, PXIe-3622, PXIe-5653, and mmWave Heads (mmHD)

HW Reference:
  • PXIe-5820 Vector Signal Transceiver
  • PXIe-3622 Vector Signal Up/Down Converter
  • PXIe-5653 RF Analog Signal Generator synthesizer/local oscillator (LO) source module
HW Requirements:
  • System controller
  • PXIe compatible chassis
  • NI PXIe-5831
  • NI PXIe-5653 (LO1 frequency range 3.2 GHz to 8.2 GHz)
  • 3-6 dB attenuator
  • Instrument capable of measuring power between 3.2 and 8.2 GHz, in this example we will be using the PXIe-5831.
  • 152 mm MMPX (m)-to-SMA (m) cable 
SW Requirements:
  • LabVIEW 2019 or later
  • RFSA 19.6 or later
  • RFSG 19.6 or later
  • RFmx SpecAn 19.1 or later
  • 5831 and 5653 LO.zip
    • RFSA Get LO Properties.vi
    • Configure 5653 LO1.vi
    • RFSG Single Tone Generation with PXIe-5653 Enabled.vi
    • RFSG Single Tone Generation.vi
Configuration Requirements:

1. Get the PXIe-3622 LO2 Frequency.

​​​​​​RFSA Get LO Properties.png
  • Open the RFSA Get LO Proporties.vi included in the .zip.
  • Set up the front panel as shown.
    • Note your Resource Name might be different.
  • Run the RFSA Get LO Properties.vi.
    • Note: The 3622 LO2 Frequency (Hz) indicator should return 4.25GHz.
    • Note: For other frequencies of interest simply change the carrier frequency.
  • Record the PXIe-3622 LO2 Frequency as this will be used later.

2.  Get the RF output power from the PXIe-5653 LO1.


Configure 5653 LO1.vi.png
  • Open the Configure 5653 LO1.vi included in the .zip.
  • Set up the front panel as shown in the example.
    • Note your Resource Name might be different.
    • Note 2 the Carrier Frequency is the value record from step 1.
  • Connect a 3-6 dB attenuator inline between the PXIe-5653 LO1 output and the measuring instrument.
    • Note:  The attenuator is to ensure the measurement instrument isn't damaged from the output of the PXIe-5653.
    • In this example we are using the PXIe-5831 as the measuring instrument.
5653 Measurement.png
  • Run the Configure 5653 LO1.vi.  
  • Measure and record the power as this will be used later.
  • Stop the Configure 5653 LO1.vi.
  • Disconnect the PXIe-5653 from the measuring instrument.

3.   Connect the output PXIe-5653 LO1 with the attenuator inline to the PXIe-3622 LO2 IN.

5831 with 5653 LO connection v1.png

4.  Execute code to export the PXIe-5653 LO1 to the PXIe-3622 LO2 IN.

RFSG Single Tone Generation with 5653 Enabled.png

  • Open RFSG Single Tone Generation with PXIe-5653 Enabled.vi that was included in the .zip.
  • Set up the front panel as shown in the example.
    • Note: the PXIe-3622 LO2 Frequency (Hz) is the result from step 1.
    • Note: 2 the LO2 In Power is the result from step 2. 
  • To perform a loopback test the following connections need to be made.
5831 Root clean final v2.png
**NOTE PXIe-5653 LO1 to PXIe-3622 LO2 connection still has the 3-6dB attenuator inline**
  • Run RFSG Single Tone Generation with PXIe-5653 Enabled.vi.
  • Open RFmx soft front panel and target the same 5831 using the RFSG Single Tone Generation.vi.
  • Configure the RF Signal Analyzer as follows.

RFmx Session.png

  • Configure the Frequency Settings as follows.
  • RFmx Spec An Settings.png

The resulting spectrum should resemble the following.RFmx Result.png
  • Note: The output power of the acquired tone will vary based upon your attenuator and measurement instrument settings.

To highlight the difference in performance you can compare the phase noise measurement results of the PXIe-5831 verses the PXIe-5831 with the PXIe-5653.  Listed below are the results:

PXIe-5831
Phase Noise.png

  • Note: Measurement result was using the RFSG Single Tone Generation.vi included in the .zip
  • Note:  Disconnect the PXIe-5653 from the PXIe-3622.
PXIe-5831 with PXIe-5653
Phase Noise with the 5653.png
  • Note: Measurement result was using the RFSG Single Tone Generation with PXIe-5653 Enabled.vi included in the .zip
  • Note: Refer to step 3 for connectivity between the PXIe-5831 and PXIe-5653
The measurement results above show ~10dBc of improved dynamic range.
 

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