MultiPath Scalar Calibration using 3 Power Sensors

Application

Used to correct the wideband power meter measurements at the the DUT reference plane including the input reflected power. The aim of this calibration is to determine, without S-parameters pre-characterization, the factor offset to apply on each power meter to get calibrated measurements. Used to calibrate input, input reflected and output ports when wideband modulated signal measurements are required:

1-Tone Measurements (Pin Available, Pin delivered, IRL, Pout, Gt, Gp, PAE, Drain Efficiency, Transducer Efficiency)
2-Tones Measurements and Video Bandwidth (VBW) Measurements (Pin Available, Pin delivered, IRL, Pout, Gt, Gp, PAE, Drain Efficiency, Transducer Efficiency, C/In, OIPn, ….)
Modulation Measurements (Pin Available, Pin delivered, IRL, Pout, Gt, Gp, PAE, Drain Efficiency, Transducer Efficiency, ACPR, PAPR, CCDF, ...)
I/Q Measurements (Pin Available, Pin delivered, IRL, Pout, Gt, Gp, PAE, Drain Efficiency, Transducer Efficiency, ACPR, PAPR, CCDF, ...)

Note: Vector Signal Analyzer is not mandatory for the calibration, but should be enabled for 2-Tones Measurements, Video Bandwidth (VBW) Measurements, Modulation Measurements and I/Q Measurements .

Setup Editor Requirement

The IQSTAR calibration wizard is linked to the Setup Editor configuration. In order to get access to the Scalar Power calibration wizard, the following conditions have to be respected:

A minimum of three Power Meter instruments (input, input reflect and output) need to be enabled
One RF Source instrument need to be enabled
I/O Switch needs to be enabled

Calibration Wizard

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

Once all required hardware is listed, click on ‘Next’.

Select the RF path to calibrate.

Note: Unselected paths won't be calibrated and so not available during measurement.

Define the frequency list and the power level to use during the calibration. The calibration power level should be high enough to get noiseless and detectable signals measured by the power meters even with the added attenuators for power sensor protection during the DUT measurents. This power level should not exceed the power meters limit.

Note: If a Driver Amplifier is enabled in the Schematic, the set power level will take into account the Driver Amplifier offset.

For High Power Amplifier characterization, it is sometime necessary to do a calibration at a power level that is beyond the limits of the power sensors. Therefore, it is possible to add, during the calibration, an attenuator to protect the power sensor. Enter the *.S2P File of the attenuator in the Adapter de-embedding file field once the box is checked.

Note: This calibration step can be performed in the 'Basic' mode as shown below, but it also possible to switch to the 'Advanced' mode in order to evaluate the linearity range of the receiver. To learn more see Absolute Power Calibration.

Once the frequency list and the power level have been defined, click ‘Next’. Then select the first path, and connect the output power meter at the first input calibration path, to extract the first input factor offset, clicking "Perform measurement".

Once the output power meter is connected to the input calibration plane, click ‘Next’ to start the process.

Once first path has been calibrated, use drop-down list to select second path and force swith matrix to swicth on second path.

This calibration step will be done iteratively for each RF path until all RF path are done and become "green".

Note: When RF paths are similar, error terms retrieved for a specific path can be used for other paths using "Copy" button. In this case, the path using error terms form another path becomes "black".

Connect a short at the input calibration plane, in order to extract the reflect factor offset.

As done for the previous calibration step, refected calibration has to be done iteratively on each path using the drop down list, selecting the path to calibrate and pressing "Perform measurement".

Once the Short (or an Open)is connected to the input calibration plane, click ‘Next’ to start the process.

Connect a 'Thru' at the calibration plane and connect the output power meter after the appropriate output attenuators. The objectif is to extract the output factor offset. Set the power level at which you desire to calibrate the output receiver. Setting an appropriated power level for the calibration of the output power meter is the key of an accurate calibration. Depending on the output power of the DUT, the external output attenuators added can have a high value (>60dB). In this case, the power level used during this calibration step should be sufficiently high to provide noiseless and detectable signals to the output power meter.

Note: This calibration step can be performed in the 'Basic' mode as shown below, but it also possible to switch to the 'Advanced' mode in order to evaluate the linearity ranger of the receiver . To learn more see Absolute Power Calibration.

In the case where the connectors at the input and output are note insertable, Male-Male or Female-Female, you need to add an adapter that must not be taken into account in the calibration. therefore, you can enter the *.S2P file of the Thru in the Thru de-embedding file field once you check the box.

Once the 'Thru' file and the power level have been set, click ‘Next’ to start the process.

Once the calibration is finished, the error terms are downloaded and recorded in the Calibrations tab. A comment is automatically added but can 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. To learn more see Validate Calibration.

Note: During the Scalar Calibration, IQSTAR performs automatically a Raw Power Calibration.