Procedures to Characterize Maury s Automatic Tuner Using ATS Software Version 5.1 or above

Transcription

1 Procedures to Characterize Maury s Automatic Tuner Using ATS Software Version 5.1 or above Things to check before tuner characterization Make sure tuner is power up and USB cable is connected to the computer Make sure GPIB cable is connected between the computer and the VNA Make sure NI software is properly installed (for ATS version prior to 5.21, only support NI version 2.4. ATS version 5.21 and above supports all NI version) Run the ATS software and it should start with the Demo.cfg by default if the software is used the first time. Setting up block diagram and drivers for tuner characterization Start with the Default block diagram by selecting the menu item FilesDefault. It will show up the power block diagram with two tuners and bias system. Change the block diagram to S-parameter block diagram from the menu SetupS-parameter Block Diagram Right click on the bias system icon and select Disable. The bias system should disappear. Also disable the tuner that you are not using. For example, if the load tuner is to be characterized, right click on the source tuner and select Disable. Make sure that the Demo mode is set to NO. To verify, select SetupOptions, and set Demo Mode to NO. Enable the VNA in the block diagram by selecting SetupInstruments. Instruments setup dialog will pop-up. Click on the Network Analyzer, then Browse for the VNA driver and check the Enabled. Select the right model number and GPIB address.

2 Verify the GPIB connection by clicking on the Test. A new window appears and clicks on the Test menu and select Find VNA, make sure the model and GPIB address are correct and click OK. A message will appear saying VNA found. Otherwise, go back and check for the driver, model number or GPIB address. Configure the tuner properties by double click on the tuner icon. Tuner properties dialog will pop-up. Click Browse for tuner driver (For all USB tuners, select TunUSB.exe ). Click on Scan and a dialog will show up with the current connected tuner model and serial number. Select it from the dialog and it will automatically update in the tuner properties window. Note: Scan button only works for USB tuners. For non-usb tuner, user needs to enter all tuner properties manually, including controller parameters. Check the tuner connectivity by click on the Test button in tuner properties dialog. A new window will pop-up. Click on Test from the menu and select Find Tuner and click OK. A message will appear saying Tuner Found. Otherwise, go back and check the tuner parameters.

3 After all the configuration are setup, the block diagram will look like one of the below, depending on the tuner selected to be characterized. The tuner is now ready to be characterized. Steps to characterize the tuner There are four methods of tuner characterization, Adaptive Modeling, Step Reflection, Step Position, and Fixed Position. Adaptive Modeling Step Reflection Step Position Fix Position Fast cal Support interpolation Most commonly used method for power measurement Evenly spaced pattern Slow cal Interpolation not supported Uneven spaced pattern Faster cal Mainly used for traditional Noise measurement Uneven spaced pattern Fastest cal Limited gamma coverage Mainly used for NP5 and Fast Noise meas To start the tuner characterization, follow the procedure below: From ATS main window, select CalibrateTunersCharacterize a Tuner, and the tuner characterization wizard will begin. Note: This document will only describe Adaptive Modeling method.

4 Select the method to characterize the tuner, and select Initialize Now if the tuner has not been initialized yet, then click next. The VNA Calibration dialog window will appear and it should read the current VNA frequencies and display the list in VNA frequencies box. The frequency list can be modified by clicking Add/Delete Frequency, or Delete All Frequency and Add Frequency Range for a new range of frequency list. Once the frequency list has been modified, click Write New VNA Frequencies to send the new frequency list to the VNA. The maximum VNA frequencies are limited to 801 points.

5 Now calibrate the VNA manually at coaxial reference plane. The accuracy of the VNA calibration is extremely important in order to obtain the repeatable and reliable tuner data (please see Maury s application note 5C-026, Verifying the Performance of VNA). Note: If the Speed Enhancement feature is to be used during characterizing (only certain VNA, which has ability to read and write error terms supports this feature), the calibration need to be save in one of the VNA s registry. For Agilent PNA model, the file name must be csetx.csa, where x being a number from 1 to 9, and the file location should be in the default directory (C:\Program Files\Agilent\Network Analyzer\Documents\). The software then recalls the cal later for fast tuner characterization). Once the VNA calibration is verified, connect the tuner to the VNA as shown below. Note that the DUT side of the tuner will always be connected to VNA port 1. Port 1 Port 2 DUT side of the tuner

6 Next step is to select the frequencies to characterize the tuner. The tuner frequencies have to be a subset of VNA frequencies, and are limited to 401 frequencies maximum. Click next and it will bring up the Tuning Range Setup dialog. Harmonic frequencies can be included (up to 10 th harmonics) during tuner characterization. In order to do that, VNA should be calibrated to 10 times the fundamental frequency. Point separation will determine number of points to be calibrated. The smaller this#, the more points will be calibrated and will take longer time. Maximum phase step will limit the phase separation at each VSWR and make sure the points are within specified phase step during tuner characterization (for better accuracy on interpolation).

7 If enabled, the VNA cal must be saved as csetx.csa, where X being an integer (1-10) and enter the number in Calset to read box (Not all VNA support this feature). Click Finish will start the tuner characterization process and repeats at all the frequencies specified to characterize. Tuner file will get saved at specified location and can be viewed after it finish.