Full 2-Ports Calibration

Application

Used to calibrate 2-ports systems when small signal measurements in Forward and Reverse modes are required:

S-Parameters Measurements (S11, S12, S21, S22)

Setup Editor Requirement

In IQSTAR, the calibration wizard is linked to the Setup Editor configuration. In order to get access to a full 2-Ports calibration wizard, the following conditions have to be respected:

Vector Network Analyzer needs to be enabled
Number of receiver of Vector Network Analyzer has to be set to 4

Calibration Wizard

To start a new calibration, select Calibrations tab and click on New Calibration . The software will verify communication with each instrument needed and will configure it using the settings previously defined.

Once all required hardware are listed, click ‘Next’.

Define the frequency list and the input and output power levels of the VNA. These power levels should not exceed the maximum power supported by the calibration kit, yet the level should be sufficient to provide noiseless and detectable signals at the VNA receivers even when adding attenuators to keep the receivers safe during the DUT characterization.

Note: It is possible to set different power levels for the input and the output port. this setting is useful when the DUT has a high gain, leading to unbalanced attenuation settings between the input and output receivers.

In the example above, the sweep type is frequency sweep starting from 1GHz to 10GHz with 50MHz step. In the example below, DUT has a 20W output power and 30dB gain. The calibration will be performed with the RF source of the VNA set to 0dBm at the input port, whereas the output port will be set to10dBm. Note that there will be a 30dB (input) and a 60dB (output) attenuator connected before the VNA’s receivers. To define appropriate attenuator values on each receiver, see 2) Power Budget.

Once the frequencies and the VNA power level have been set, click ‘Next’.

At this step, a classic Full-2 ports calibration using the VNA interface has to be performed.

Note: All the parameters (IFBW, Power level, Frequency sweep, Pulse Timings) will be automatically set in the VNA, according to the Setup Editor configuration. Depending on the VNA model, a 'Single' Trigger is needed to update the settings.

When the calibration is finished on the VNA, go back to IQSTAR and press ‘S-Parameters calibration Check’ to validate your vectorial calibration or save a 'Thru.s2p' file. Learn more see Validate Calibration.

Note: It is recommended to save the calibration state on the VNA so it can be reloaded by IQSTAR without having to redo the vector calibration. Just reload the calibration on the VNA when prompted in IQSTAR to perform a Vector calibration and then click next in IQSTAR calibration wizard to reload all the error terms.

Note: If the frequency list contains too many points, the VNA sweep may take a long time and may cause a timeout error. To avoid this issue, one need to increase the VNA timeout in the instrument settings Vector Network Analyzer

Once the calibration has been completed, the error terms are downloaded and recorded in Calibrations tab. A default comment is automatically added but it could be modified. This calibration will be used by default for the measurement unless the box Use this calibration is unchecked.

Quick checks can be performed to verify the accuracy of this calibration using Validate calibration button. To learn more see Validate Calibration.