IVCAD VNA Base Load Pull with Active/Hybrid Tuning Getting Started v3.5
1 Setting and Configuration Block Diagram... 3 1.1 VNA setup... 5 1.2 RF source setup... 6 1.3 Power meter setup... 7 1.4 Source tuner setup... 8 1.5 Load tuner setup... 9 1.6 Power supply setup... 12 2 Calibration... 15 3 Calibration Verification using a through standard... 22 4 Device measurement... 30 2 P a g e
1 Setting and Configuration Block Diagram Before setting up IVCAD, the tuners need to be calibrated using ATS software and have the tuner files ready. The procedure to characterize the tuner can be found in the ATS s Help directory. Note that there are two USB tuner drivers in ATS (TunHubMech.exe and TunUSB.exe). One must be consistent using the same tuner driver in ATS for tuner characterization and the device measurement in IVCAD. Launch the IVCAD program and expand Measurement on the left under Plug-ins. Click on Setup & measurement and then New. A dialog will pop-up and will ask user to select either IV-measurement or VNA based LP measurement. Select the VNA based LP measurement. 3 P a g e
A new block diagram for load pull will show up. 4 P a g e
1.1 VNA setup Click on the VNA icon and setting up parameters for the VNA. Click on Test connection button and check for the connection. If unsuccessful, double check driver and address and make sure they are correct. VNA allows GPIB or LAN interface. For LAN we deeply recommend SICL protocol (TCPIP0:: IP address of the instrument ::inst0::instr) instead of SOCKET protocol (TCPIP0:: IP address of the instrument ::5025::SOCKET). Note that a 4-port PNAX is used for this demonstration and receiver port 3 and 4 are used for measurement. For more information on configuration using different VNA model, refer to the document IVCAD OM LoadPull MT930C.pdf from IVCAD s help menu. For X-parameter measurement with NVNA, port 1 and 3 must be used for standard configuration. 5 P a g e
1.2 RF source setup Click on the Src1 icon and setting up parameters for RF source. (Note: Src2 will not be used) Note: To use the internal RF source for the measurement take care about the internal isolation between source and receivers (a test procedure is depicts in the VNA Operating manual of IVCAD) To use internal RF source of the VNA set the address of the VNA, it s possible to use GPIB or LAN protocol (TCPIP0:: IP address of the instrument ::inst0::instr). 6 P a g e
1.3 Power meter setup Click on the Power Meter icon and setting up parameters for power meter. 7 P a g e
1.4 Source tuner setup Click on the Source tuning station icon and select the type of tuning mode (Passive, Active or Manual Hybrid), then setting up parameters for source tuner. 1 2 3 4 5 8 P a g e
Click on the Mode tab and select the tuning mode. The different between each tuning mode and their capability is described in the Tuner configuration dialog in the previous page. Click on the Harmonic tab and enter the weight of the tuning requirement in case a multiharmonic tuner is used. Select the calibrated tuner file from the drop down list. 1.5 Load tuner setup Click on the Load tuning station and setting up parameters for the load tuner. When setting up load tuner, it will first ask for the tuning mode; passive, active or manual hybrid. Passive will be purely mechanical tuner, active is going to be purely active injection (also called active load pull), and manual hybrid will be passive tuner combined with active injection for both at fundamental and harmonics, depending on the active source setup. (Note: Manual hybrid setup will be demonstrated in this document) 9 P a g e
Click on the Passive tuner tab and configure for the passive load tuner. It is going to be exactly the same as source tuner configuration as described before, except for load termination file. Click on the Deembedding tab and select termination file from the drop down list. Click on the Active tuner tab and configure for active source. Select the number of active RF source (support up to 4 active sources). Check each RF source to enable the source to be used. 10 P a g e
Click on the RF source number (the button with label <undefined> ) that needs to be configured. Repeat for additional RF source if the harmonic count is more than 1. Auto range option may be selected to use very low power (lower than -30dBm for most of the RF source), but the use of this option may cause some phase shifting caused by the internal attenuators. Use of External RF source is preferable is this case. 11 P a g e
1.6 Power supply setup Click on the power supply icon on the block diagram and setting up for power supply. 1. Check Enable to active the power supply 2. Check Input (for gate), output (for drain) and any auxiliary supply that need to be used in the setup. 3. Check Same input and output measurement instrument if the power supply is multi channels and uses the same power supply to bias both gate and drain. 4. Check Power off after measurement and the power supply will be off after measurement. Otherwise, it will leave the power supply on until user manually turn it off. 5. Make sure that the power ON sequence is in the right order. Click on the up and down arrow to change the order. Click on the input power supply to configure the instrument. Click on Test connection to check the GPIB connection. 12 P a g e
Click on the output power supply to configure the instrument. Click on Test connection to check the GPIB connection. Click on the measurement unit button and configure the instrument used to measure voltage and current. 13 P a g e
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2 Calibration Once the block diagram is setup and properly configured, we can proceed with the calibration. The actually hardware setup for calibration will look like the diagram below. Note that the attenuation for the receiver input need to be carefully selected so that the power going into the receiver will stay below -20dBm which is the receiver s linear operating range. PNAX PM PS Rcv R3 Rcv C Rcv D Rcv R4 Cal ref B.T B.T Click on the Calibration tab and then click New Calibration to initialize the calibration wizard. Select Coaxial power calibration for in-fixture DUT, and Unsexed power calibration for onwafer DUT. Also select where the power sensor to be connected for amplitude power calibration. 15 P a g e
Click Next and all the instruments as well as tuners will be initialized and it will show up the hardware with a green check. If there is any red cross appears next to the hardware, it needs to go back check the setting for that specific hardware. 16 P a g e
Next dialog is to setup the power level to perform 2-ports vector calibration and the frequency. Select whether frequency sweep, 1-tone, or 2-tones depending on the type of measurement. Click on Inject into list to register the list of frequencies to be calibrated. Click next and the VNA will be configure according to the setup and ready for the calibration. Use VNA front panel to perform 2-port vector calibration (see the diagram for the calibration reference). 17 P a g e
Click next when the calibration is done, and the following dialog will ask to calibrate the power sensor. Skip this step if the sensor is already zeroed and calibrated. Otherwise, perform power sensor calibration and click next when it is done. In the next dialog, setup the power level to perform amplitude calibration. Pmax power sensor is the maximum power that the power sensor can handle. Pinitial source power is the starting power of the RF source for optimization. Ptarget power sensor is the power level to be read at the power sensor reference. 18 P a g e
Next dialog will display where the sensor should be connected. Connect the power sensor on the port as shown in the diagram and proceed to the next step. Click next and it will start to perform a power sweep base on the Pinitial and Ptarget from the previous dialog. 19 P a g e
Once the amplitude calibration is done, click next to finish and enter a comment is needed. After the calibration, a calibration with an ID number is assigned under Available calibration section on the right. 20 P a g e
At this level, it is possible to run an automatic determination of the S parameter block files which are in front of the tuners, and at the rear of the tuners, if these ones have not been taken into account during the tune calibration. This one will be needed in order to drive the tuners directly at the right impedance. Select the line which corresponds to the calibration of interest. Select Tuner autodeembedding, and the frequencies of interest. The frequencies available will be the common frequencies which can be found into the source and load tuner calibration files, plus the VNA calibration. 21 P a g e
3 Calibration Verification using a through standard Once the calibration is finished, the driver amplifier can be added at the input to drive the input power and it will not affect the receiver calibration. The VNA cable at the output can be removed and terminate the load tuner with the components that used to obtain the load termination file (.s1p). For active/hybrid setup, the termination could include isolator, diplexer/triplexer, amplifier, etc. The actual hardware setup for active/hybrid load pull measurement will be similar to the diagram shown below. PNAX AMP AMP Rcv R3 Rcv C Rcv D Rcv R4 Cal ref LPF B.T B.T com HPF 50Ω The setup need to be initialized before the actual measurement can be performed. Click on the Initialize bench from the measurement menu and all the instruments will be initialized and the calibration ID will be recalled and write it to the VNA. 22 P a g e
Once the bench is initialized, go to common tab and enter the fundamental frequency and number of harmonic to be measured. Scroll down and enter the file name under desire directory. 23 P a g e
Click on Power sweep tab and enter power type and desire power range for the sweep. There are 4 different power type user can selecte. i. Raw power the power generated at the VNA ii. Source power available power at the DUT iii. Input power Power deliver at the DUT iv. Output power Power deliver at the device output Next step is to set the source and load tuner to be conjugate of each other. 24 P a g e
From the Plugins under Measurement, click on Tuner Manager. The smith chart for source and load tuning station will appear. o 1/ Select the F0 frequency o 2/ Set the source gamma (0.8 and 120 for source, 0.8 and -120 for load) o 3/ Click on Move button after setting the gamma every time. 25 P a g e
If the active source is disabled, only the passive tuner will be used to get to target gamma. If active source is enabled, passive tuner will operate as a pre-match tuner and active tuning will be used to get to the target gamma. If 2 nd harmonic active source is enabled when using a fundamental tuner, the matching is only done by the harmonic active source because pre-match may not be optimal. Go back to Setup & measurement and click on Start on the right top corner to begin a power sweep. 26 P a g e
Once the measurement is done, IVCAD display a report about the measurement To view the data in visualization, enable the source data file in Datasource and click on Visualization under Plugins. Expend Load Pull and click on Load Pull viewer. A power sweep curve will be display on the right window and user can select to display different parameter from the Custom tab above the graph. Select the parameter to be Power gain as we are expecting 0dB for a through. 27 P a g e
Check the power gain curve and it should be around 0dB Also check the Gamma_in magnitude and phase and it should be the same as gamma load of 0.8 magnitude and -45 degree as we set it in the load tuning station. 28 P a g e
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4 Device measurement Once the power gain and gamma_in are verified, the calibration is considered to be accurate and the device measurement can be performed. The first thing to do after putting the DUT is to check the bias. Click on the DUT biasing from the plug in window. Click Power supplies ON, enter the voltage for gate and drain, click on Apply levels and check the current. 30 P a g e
Go back to the Setup & measurement and enter the frequency, stop conditions and the file name. 31 P a g e
Now user can freely choose to perform either power sweep or impedance sweep. The common procedure would be to perform source pull first to find out the best impedance for power gain. Leave the source impedance at optimum gain and perform load pull at around 1dB or 3dB compression for optimum output power or PAE. Then perform power sweep while the load impedance is set to either optimum power or PAE. To select impedance pattern in the impedance sweep select the shape and configure it, once the preview (blue point) is correct press Add to validate the pattern. It s possible to add as many pattern shape as needed. To perform source pull, click on impedance sweep tab and select Source pull for optimization type. Also select power type and power level to do the source pull. To select the source impedance, scroll down and select one of the four tabs below the smith chart for different impedance pattern. 32 P a g e
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Once the impedance is set, click on the Start from the top right corner to start the measurement. The display will show the load and source gamma, as well as the source pull contour in real time. 34 P a g e
When the measurement is done and the data is loaded into the data source, the source pull contour can be display using visualization. 35 P a g e
To perform load pull, select the optimization type to Load Pull and select the load impedance and click Start to initiate the measurement. Example of load contour is displayed below from visualization. 36 P a g e
To perform active fundamental or 2 nd harmonic active load pull, simply select the active source from load tuning station, then select either f0 or 2.f0 for optimization frequency under impedance sweep tab and select the impedance pattern to be measured, Click Start to initiate the measurement. 37 P a g e
To perform power sweep, click on Power sweep tab and enter power type and power range. Click Start to initiate the measurement. When the measurement is finished, load data into data source and the Pin vs. Pout and PAE curves can be viewed using visualization. Note: For additional software features, terms and definitions please refer to the IVCAD operation manual IVCAD OM LoadPull MT930C.pdf which can be found in IVCAD s Help menu. 38 P a g e