NPR Measurement Panel: Source

This tab allows defining the I/Q waveform which will be loaded by the RF Source.

Unlike Modulation Measurements, there are only two different modulation loading modes:



Waveform

  • From Waveform Generator: This panel is similar to Modulated measurement sweep settings panel. To learn more see From Waveform Generator.
  • Waveform file: This panel is similar to Modulated measurement sweep settings panel. To learn more see Waveform file.

Waveform Source Optimization

If enabled, two main settings are available:
  • Equalization: This setting is used to compensate any distortion usually visible in the signal band, implied by the non linearities of the different RF components used in front of the DUT input plane such as drivers, couplers... This lead to a poor signal flatness over the band, made worse the higher the signal bandwidth is. In order to compensate it, IQSTAR can perform a test measurement to analyse the spectrum at the DUT reference plane via the receivers spectrums, and process the data in order to linearize it at best.
    • Iteration: The number of iteration to perform to linearize the spectrum. Usually one is performing well, but using an higher value can improve a little more the flatness. Using too much can lead the algorithm to unconvergence issues and result in a completely wrong spectrum.
    • Force at each power: If checked, the linearization will be performed at each power value of the power sweep. It can be necessary if working in the non linear regions of devices in the RF path in order to ensure linearity at each power level.
  • LO feed through: Regarding the signal used, the LO signal can leak and be seen on the waveform. This particularly happens when the NPR signal notch are located on this LO frequency. To reduce the magnitude of this LO tone appearing on the spectrum, we can apply an offset to the I and Q values.
    • Optimization: Using this option lets the software optimizing the I and Q values via an iterative algorithm. It can cost time regarding the offset values to apply to obtain the minimum leakage, as the number of iteration to converge can be high.
    • Fixed offsets: Manually sets a fixed offset for I and Q values during the measurements.