Deembedding

In the Deembedding tab on the lower right portion of the Probes/External Hardware Setup dialog box, you have these controls:

• Correction Mode — Use this drop-down list to select between Automatic and Off.

  Automatic — When a probe contains an S-parameter description of its own electrical characteristics, as with InfiniiMax probe amplifiers, the oscilloscope will apply the proper correction for the probe. This is known as factory AC response calibration.

  When automatic probe correction cannot be completed, the channel data will have a questionable status with one of the following status reasons:

  • No transfer function was available for this probe. Channel data is uncorrected.
  • Probe transfer function was invalid. Channel data is uncorrected.
  • De-embedding output was too low for this probe. Channel data is uncorrected.

  In all three cases, the channel data is still acquired and analyzed, However, the data does not have any probe correction applied. Any downstream analysis such as measurements or functions will also contain the same status.

  Beware of analyzing uncorrected data.

  These statuses should not occur, and they should be reported to Keysight if they do.

• Response — Use this drop-down list to select how the time domain and frequency domain response is characterized:

  • True View: Vout/Vin — Characterizes the output of the probe as a function of the input at the probe tips. Defining the response this way lets you evaluate the probe's accuracy in reproducing the actual signal present in your system with the probe attached. This correction is what you would see with a real band-limited probe that has finite input impedance.

    The oscilloscope corrects the “Vout/Vin” response to be flat with frequency and phase to your defined bandwidth limit. It does not de-embed the loading effects of the probe.

    Keysight's probe corrections are typically defined using Vout/Vin.

  • Source Estimate: Vout/Vincident = Vout/Vsrc — This method corrects the probe as “what would be there if the probe were not present”.

    One drawback of defining the probe’s response in this manner is that if the probe’s loading causes your circuit to lose some timing or amplitude margin, you probably want to know that when you make a measurement. Vout/Vsrc compensation will hide these effects from you.

    However, this method can be effective if probing at the transmitter.

    When Vout/Vsrc is selected, the system source impedance is 25 Ohms.

  You can learn more about these types of probe response corrections in Keysight Application Note 1491,  Side-by-Side Comparison of Probing Measurements on High-Speed Signals.