This LabVIEW example demonstrates fast and accurate load-pull measurements under continuous wave (CW) or digitally modulated conditions, by combining the NI Vector Signal Generator (VSG) and Vector Signal Analyzer (VSA) or the NI PXIe-5644R or NI PXIe-5645R Vector Signal Transceiver (VST) with a Maury Microwave LXI-Certified Tuner in a compact system.
Note 1: The Code is provided As Is. It has not been tested or validated as a product, for use in a deployed application or system, or for use in hazardous environments. You assume all risks for use of the Code and use of the Code is subject to the Sample Code License Terms which can be found at: http://ni.com/samplecodelicense
Note 2: This example has been tested with the NI Vector Signal Transceiver as VSG and VSA (both NI-PXIe-5644R and NI-PXIe-5645R models). By design, this example should work also with all RFSG and RFSA models supported by the NI RFSG and the NI RFSA drivers respectively but it has not been tested yet.
This LabVIEW example allows you to perform a source- and/or load-pull sweep using Maury LXI tuners under CW or modulated conditions, for a given carrier frequency, using a vector signal generator (VSG) and a vector signal analyzer (VSA).
In addition to source and/or load impedance sweep, the application allows you to sweep the available power (Pav) at the device under test (DUT) input port, and up to 2 NI DC SMU channels in order to bias the DUT.
At each sweep point, the application retrieves different measurement results such as RMS and Peak delivered output power (Pdelout), transducer gain (Gt), DC voltages and currents and (drain) efficiency. When performing measurements under modulated conditions, additional measurement quantities are available such as IQ imbalance or error vector magnitude (EVM).
The measurement results can then be visualized on the fly using Source and Load Smith Charts or 2D plots versus Pav.
Finally, the results can be saved to file, using Maury source- and load-pull file formats, and then be imported in ADE tools such as AWR Design Environment for further visualization purpose.
When the DUT is in fixture, one can specify the S-parameters(*) of the path between the fixture ports and the DUT pins, at input and output side respectively.
For power application, a pre-amplifier can be included in the setup, and some nominal amplifier values must be specified in the application to avoid over-driving the pre-amplifier and/or the DUT.
In order to stay out of the 1W (30dBm) maximum handling power of the VST RF input, proper attenuation might be required and the corresponding S-parameters1 must be specified as part of the Back Port block.
When the setup is configured, one needs to perform an input power calibration to determine the required VST source power to achieve a desired Pav at the DUT input port.
(*) The port convention of the different blocks is shown in the configuration tab of the application.
Open the Load-Pull Project.lvproj and run the SourceAndLoadPullApplication.vi
Refer to the LoadPullProject_LV2012_v2_1_GSG documentation, in the Load-Pull Project under Documentation, for further help on running the application.
Please note that the equation on page 14 and 19 (inside the pdf) for calculating the Loss are not correct. The term in the denominator should contain the gamma_term instead of gamma_tuner. The LabVIEW codes seems to be ok.
The equations have been fixed in the documentation.