Go to www.awrcorp.com
Back to search page Click to download printable version of this guide.

Generalized Load Pull Contours Aligned to a Value: G_LPCM_A

Summary

G_LPCM_A can be used to align the data along the iPower dimension to a user-specified quantity and value. This measurement should only be used with swept power load pull files (files with a swept iPower). This measurement allows the data plotted for a contour to be derived from consistent specification of the input power level over all the impedance points. A typical use is when the data to be contoured is PLoad, and the data to align to is G_Compress. The Align type is set to "Align to specify", so the next parameter in Align to specify value is used. If Align to specify value is set to 1, the Data to align to is aligned to the 1db compression point. Aligning to a compression point is a common use for this measurement, but it can also be used to align to other quantities such as a fixed available input power, which can correct for variations of available power over gamma due to imperfect measurement conditions.

For any aligned data measurement you should visually verify aligned data by plotting the aligned computed value to itself using the PlotMD_R_A measurement.

Because the data is aligned by "sliding" it along the iPower sweep dimension, selecting an iPower value at which to plot the data is very important. You can do so manually by visually inspecting the aligned data or by finding the appropriate warning in the Status Window, but the recommended approach is to use the "Auto Align" option for the iPower index which correctly chooses the index at which the data is aligned for contour plotting.

Parameters

Name Type Range
Load Pull Data File Name Subcircuit A/B Wave Load Pull File or Derived Value Load Pull File
Data for contour   Calculated Values
Contour Step or Value   1; When Max number of contours > 1, the contours are automatically generated based on even multiples of the step size. When Max number of contours = 1, this value is used for the contour value. For data that has units, the step value is specified in base units, even if the values are displayed in user units. For example, if you plot the contour of AMPM values for a load pull file, and the unit setting for angles is set to degrees, then the Contour Step or Value size is specified in radians, even though the contour values display as degrees.
Max number of contours Real -500 to 500; if 1, Contour Step or Value is used to specify the value.
Z0, real (ohms) Real 0.1 to 2500; the normalization impedance used to display the contours on the Smith chart.
Z0, imag (ohms) Real -2500 to 2500; the normalization impedance used to display the contours on the Smith chart.
Data to align to   Calculated Values
Align type   Center (Default) aligns the data by shifting the traces both to the left and to the right such that the data lines up with the user-specified value.
Shift right aligns the data by shifting the traces to the right such that the data lines up with the user-specified value. This type is recommended for all computed values, especially G_Compress or IPN since shifting to the right does not cause the traces to drop their lowest power point as the data is shifted (note that they may drop higher power points than needed for the specified value but that is acceptable).
Shift left aligns the data by shifting the traces to the left such that the data lines up with the specified value.
Shift right & refine aligns the data by shifting the traces to the right such that the data lines up with the user-specified value and then iteratively refines the aligned solution a few times to see if the specified goal is better achieved. This type is recommended for any aligned data where visual inspection of the aligned data indicates a poor alignment.
Center & refine aligns the data by shifting the traces both to the left and to the right such that the data lines up with the user-specified value and then iteratively refines the aligned solution a few times to see if the specified goal is better achieved.
Shift left & refine aligns the data by shifting the traces to the left such that the data lines up with the user-specified value and then iteratively refines the aligned solution a few times to see if the specified goal is better achieved.
Align to specify value   Aligns to this value when Align type is Align to specify.

Options

In addition to the standard parameters, you may need to specify the following swept parameters.

Sweep Description
iPower Index into the values used for swept power. It is recommended to use Auto Align. If Align type is "Align to specify" for example, then there is only one iPower index where the measurement is actually aligned to the specified value. Exposing the iPower sweep allows insight into how the contours change over power, but it also adds an extra step if you want to see the contours at the specified alignment value. When the measurement is run, it automatically posts a message (as a warning message) to the Status Window to indicate the iPower index at which the data is aligned.
harm Specifies which harmonic to use.

Please send email to awr.support@ni.com if you would like to provide feedback on this article. Please make sure to include the article link in the email.

Legal and Trademark Notice