Gain Compression Calibration


The GCA Calibration Wizard guides you through a calibration of GCA or GCX channel. The procedure is the same regardless of the Gain Compression Settings. Option 086 or S9x086A/B is required.

See Also

Gain Compression Application

Gain Compression for Converters

Calibration Programming commands

 

How to start a GCA Calibration

Using Hardkey/SoftTab/Softkey

Using a mouse

  1. Press CAL > Main > Smart Cal....

  1. Click Response

  2. Select Cal

  3. Select Smart Cal...

Overview -  GCA Source Power Cal

The GCA Calibration Wizard first performs a Source Power Cal. The GCA Source Power Cal is a little different from a standard Source Power Cal. Although GCA measurements are performed at many power levels, the GCA source power cal is performed at a single power level over the specified frequency span of your GCA measurement. The required source correction from that single power level is applied to ALL power levels.  This method ensures that the 'absolute' power level being applied to the DUT is within the PNA-X source power linearity specification.

Although it is important for GCA to be able to set the absolute power level to the DUT, it is MOST important to be able to exactly measure the actual incident power. Therefore, during the GCA Source Power Cal, a receiver calibration is applied to the port 1 reference receiver, and indirectly to both test port receivers during the S-parameter calibration, correcting for impedance mismatch between the power meter and the VNA source, and the DUT and the VNA source.

Although the cal process is also at a single power level, the dynamic accuracy of the PNA-X receivers is typically about +/- .05 dB, which is comparable to the accuracy of Keysight's best power sensors. This allows GCA to very accurately measure and report ALL power levels that are actually applied to the DUT.

Full 2-port or Enhanced Response (ER) Cal

By default, a full 2-port calibration is performed as part of a GCA and GCX calibration. However, you can change to an Enhanced Response Cal.  The following issues may help you decide between these two Cal types:

How to select Enhanced Response Cal

At the Select DUT Connectors page of the GCA Cal Wizard:

  1. Check Modify Cal, then click Next.

  2. A Defined Thru or a Flush Thru Cal method must be selected.

  3. Click Cal Type/Stds

  4. Under Calibration type, select EnhResp  (2 <= 1 refers to the receive port 2 and source port 1).

Downgrade a Full 2-port Cal to Enhanced Response Cal if you prefer to perform a Full 2-port cal, but not perform reverse sweeps on the DUT.  

To change the correction on the channel from Full 2-port to Enhanced Response:

  1. Press CAL > Main > Correction Methods.

  2. Select GCA EnhResp, then OK.

 

GCA Cal Wizard

Select DUT Connectors and Cal Kits - GCA Cal dialog box help

This is a standard Cal Wizard page except for the following:

Power Sensor  Specify the connector type and gender of the power sensor. When the power sensor connector is not the same type and gender as the DUT Port 1 connector, then an adapter is required to connect the power sensor to the port 1 reference plane during the Source Power Cal. An extra 1-port cal is performed to measure and correct for the adapter. No characterization S2P files are required.

  • Select Ignored (at the bottom of the DUT Connectors list) to NOT compensate for the adapter.

  • Select the Cal Kit that will be used for that process.

Modify Cal  Check, then click Next, to Modify Cal (Standards AND Thru Method).

Source Cal Settings  Click to launch the Source Cal Settings dialog.

Learn more about GCA Source Power Calibration

 

Gain Compression Calibration Step 1 dialog box help

Power Level at which to perform the Source Power Cal.

It is usually best to perform the Source Power Cal at 0 dBm because the power sensor is calibrated at that level.

However, if the Gain Compression measurement is performed entirely below or above 0 dBm, then perform the Source Power Cal at the Stop power which probably has the lowest level of measurement noise.

Learn more about GCA Source Power Calibration

The remaining Gain Compression Cal dialogs are the same as the standard SmartCal dialogs.

Return to Gain Compression Application.