PXIe VNA Help
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Active Hot Parameters

This application measures the optimum Gamma that provides the maximum delivered power for nonlinear devices. Unlike classic S-parameters, which capture only linear device behavior and ignore nonlinear behavior, X-parameter terms (Xf, Xs, Xt) are used to predict the Gamma that yields the optimum power delivered to a load from a nearly matched device under large-signal drive and thus define the nonlinear behavior of the DUT.

The X-parameter terms assume the following:

In this topic:

Features and Requirements

Features

Requirements

Measurement Parameters

How to Make Active Parameter Measurements

Create an Active Parameter Channel

  1. On the VNA front panel, press Meas > Main > Meas Class....

  2. Select Active Parameters, then either:

  1. An Active Parameter measurement is displayed.

Configure Active Parameter settings

Using Hardkey/SoftTab/Softkey

Using a mouse

  1. Press Freq > Main >  AHP Setup....

  1. Click Stimulus

  2. Click Frequency then select ACTS Frequency...

Active Parameter Sweep tab help

Sweep Type - Sets the sweep type to the active channel:

Linear Frequency  Sets a linear frequency sweep that is displayed on a standard grid with ten equal horizontal divisions.

Log Frequency  The source is stepped in logarithmic increments and the data is displayed on a logarithmic x-axis. This is usually slower than a continuous sweep with the same number of points.

Power Sweep  Activates a power sweep at a single frequency that you specify. Learn about power sweep.

Multisweep  Selects multiple sweep. This is also called 3D sweep (power, phase, and frequency). Each sweep can be set to a different power level. Within each sweep is a 2D sweep of phase and frequency. With a fixed input power, a frequency-swept trace is useful to analyze the DUT’s frequency response. With fixed input power and fixed frequency, offset-phase measurements are performed to get adequate values to compute the “active S22” and X parameters.

Linear/Log Frequency Sweep Type

Source

  • Start Frequency  Sets the beginning value of the frequency sweep.
  • Center Frequency  Sets the center frequency of the frequency sweep.
  • Stop Frequency  Sets the end value of the frequency sweep.
  • Frequency Span  Sets the frequency span of the frequency sweep.
  • Number of Frequencies  Sets the number of data points that the analyzer measures during a sweep. Range: 2 to 20001.(Default is 201).
  • Power Level  Sets the power level of the source. Learn more.

Power Sweep Sweep Type

Source

  • Start Power  Sets the beginning value of the power sweep.

  • Stop Power  Sets the end value of the power sweep.
  • Number Of Powers  Sets the number of data points that the analyzer measures during a sweep. Range: 2 to 20001. (Default is 201).
  • CW Frequency  Sets the single frequency where the analyzer remains during the measurement sweep.

Multisweep Sweep Type

Source

  • Start Frequency  Sets the start frequency of the frequency sweep.
  • Center Frequency  Sets the center frequency of the frequency sweep.
  • Stop Frequency  Sets the stop frequency of the frequency sweep.
  • Frequency Span  Sets the frequency span of the frequency sweep.
  • Frequency Sweep  Sets the sweep type.
  • Number of Frequencies  Sets the number of data points that the analyzer measures during a frequency sweep. Range: 2 to 20001. (Default is 201).
  • Start Power  Sets the beginning value of the power sweep.
  • Stop Power  Sets the end value of the power sweep.
  • Number of Powers  Sets the number of data points that the analyzer measures during a power sweep. Range: 2 to 20001. (Default is 201).

Extraction

  • IF Bandwidth  Sets the IF (Receiver) bandwidth. Learn more.

  • Absolute Power  The tone power is an absolute power.

  • Relative to Input Power  The tone power is relative to the input power (dBc).

Extraction Tone (ET) Level

The level of the extraction tone must be small enough to ensure a spectrally-linear response, but large enough to ensure that the response is measurable.

A Source Power Cal is performed and both the LSOP (large signal output power) and Extraction tones power levels are adjusted to compensate for loss, external amplifiers, and attenuators.

Select the method used to set the ET Power Level:

The goal of both of the Absolute and Relative ET Level methods is to set the ET level ~16 dB below the LSOP level while ensuring a spectrally-linear response from the DUT.

    • Relative to the Input Power
      For example: At the DUT output you know that the DUT gain at the maximum stimulus power is 12 dB. The extraction level is set to -4 dBc (DUT Gain – 16 dB).
    • Absolute Power
      For example: You know that the DUT gain is 12 dB with the stimulus power at -10 dBm. Then the DUT Max Output power is +2 dBm. The extraction level is set to 16 dB below +2, or -14 dBm (Input Stimulus + DUT Gain – 16 dB).
  • Number of Phases  Sets the number of phase points. At each point, a phase sweep is performed. Several stimulus states are required to extract the unknown parameters. The following is an example of the output power in Polar format with the number of phases set to 21. Note that the oval shown below is due to the non-linearity of the device. The perfect circle shown below is a linear device.

DC

Active Parameter RF Path tab help

Power On - all channels - Check to enable source power for all channels.

Source

  • Source Port  Selects the port through which an internal source is available.

  • Receiver A Attenuator  Sets the Receiver attenuation.

  • Receiver Leveling  Turns receiver leveling on/off. This function adjusts the source power until the measured receiver power is equal to the Port Power.

Extraction

  • Extraction Port  Selects the port to measure the output of the DUT.

  • Receiver C Attenuator  Sets the Receiver attenuation.

  • Receiver Leveling  Turns receiver leveling on/off. This function adjusts the source power until the measured receiver power is equal to the Port Power.

RF Path Config...  

Active Parameter X-axis tab help

This tab allows the user to select a subset of the data to be displayed on the screen (frequency, power, phase) by defining the x-axis and a set of fixed values for the other parameters.

Active  Selects a trace to be active. A trace must be active before its trace settings can be changed.

Select all traces  Check to select all traces.

X-axis display  Sets the x-axis sweep type.

Frequency

    • Fixed Parameters

      • Input Power  Sets a fixed input power level.

      • Enable interpolation  Check to enable displayed data to be computed by interpolation.

Power

    • Fixed Parameters

      • Frequency  Sets a fixed frequency.

      • Enable interpolation  Check to enable displayed data to be computed by interpolation.

Phase

    • Fixed Parameters

      • Input Power  Sets a fixed input power level.

      • Frequency  Sets a fixed frequency.

      • Enable interpolation  Check to enable displayed data to be computed by interpolation.

DC

    • Fixed Parameters

      • Input Power  Sets a fixed input power level.

      • Enable interpolation  Check to enable displayed data to be computed by interpolation.
    • Name

      • AO1 Internal DC source #1.

      • AO2 Internal DC source #2.

Active Parameter Analysis dialog help

This dialog is identical to the X-axis tab above.

Access this dialog by right-clicking in the trace status area then selecting Active Parameter Analysis...:

Accessing Measurement Parameters

How to select and configure Measurement Parameters

Using Hardkey/SoftTab/Softkey

Using a mouse

  1. Select a trace by pressing Trace > Trace N >  Trace N.

  2. Press Trace > Trace Setup >  Measure....

  3. Select a parameter.

  1. Right-click on a trace.

  2. Select Measure Tr N.

  3. Select a parameter.

Active Hot Parameters help

Option S9x111A/B Measurement Parameters

Note: In the example below, Port 1 is the Source Port (DUT input) and Port 3 is the Extraction Port (DUT output). Port 3 or Port 2 can be chosen as the output of the DUT.

IPwr  Check to measure input power.

OPwr  Check to measure output power.

HotS31  Check to measure Active Gain.

HotS33  Check to measure Active Output Match.

HotS13  Check to measure Reverse Isolation.

HotS11  Check to measure Active Input Match.

Gamma  Check to measure optimized Gamma.

Pmax  Check to measure maximum delivered power.

Xs(3,3), Direct Reflection Coefficient. The fundamental XS33 parameter which is used, in combination with XT22, to describe the change in b2 as a function of a2, the signal reflected from the load.

Xt(3,3), Direct Reflection Coefficient. The fundamental XT33 parameter which is used, in combination with XS22 to describe the change in b2 as a function of a2, the signal reflected from the load.

Xf(3,1), Output Coefficient. The fundamental XF31 parameter.

DeltaOPwr  Check to measure the delta between the output wave and output power to Z0 load.

Available for option S9x111A/B only (the following traces are not restricted to 50 GHz)

HotGain  Check to measure forward gain using linear S-parameters output/input.

HotMatch  Check to measure active output match using linear S-parameters.

Buttons

Select All  Click to select all measurement parameters.

Clear All  Click to deselect all measurement parameters.

Create in New Window  Check to create a new trace in a new window for the measurement.

Channel Number  Select a channel number for the measurement.

Calibrating an Active Parameter Channel

A calibration can be performed on the Active Parameter Channel using the Cal All Wizard.

Saving Data

The data can be saved to a *.csv file with a column for each measurement parameter.

How to save data

Using Hardkey/SoftTab/Softkey

Using a mouse

  1. Press Save Recall > Save Other >  Save Data....

  2. Save as type = HotS22 Sweep Data (*.csv)

  1. Click File

  2. Click Save Data....

  3. Save as type = HotS22 Sweep Data (*.csv)