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WaveForms v3.9.1 to v3.10.9 Impedance problems


Rick314

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I am getting significantly different results with the attached .dwf3work file that was created using WaveForms v3.9.1 and is now being used with v3.10.9.  The 3 images below are:

  1. Version 3.9.1 results.
  2. Open the .dwf3work file in WaveForms 3.10.9. Turn on the Factor window to see Quality and Dissipation. Adjust window size and position. So far things look good and the results from the previous v3.9.1 measurement are shown as expected.
  3. Run the Impedance measurement in v3.10.9.

There are several differences in the v3.10.9 results.  Perhaps these come from a common problem, but what is wrong?

  • The Input window trace changed from attenuation (0 to +27 dB) to something I don't understand with values from +60 to -30 dB.  (I had to re-scale to get these values.)
  • In the Impedance window, the Rs results changed dramatically.
  • In the Admittance window, the Gp results changed dramatically.
  • In the Factor window, Quality and Dissipation results changed dramatically.
  • In the Nyquist pane, the results changed dramatically.

(Edit added after posting: This is using an Electronics Explorer board, measuring a series 1 kohm resistor and shunt 250 nF ceramic capacitor.)

190324_Impedance1_v3.9.1.png

190324_Impedance2_v3.10.9_pre-run.png

190324_Impedance3_v3.10.9_post-run.png

190324_Impedance.dwf3work

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Hi @Rick314

In v3.9.1 the Input was measuring Scope1/2
Later this was changed to show DUT/Resistor to be regardless of the used circuit model.

The difference in (Rs,Gp,Q,D) measurements due to different Scope input gains.
In 3.9 it was called Auto now it is renamed to Amplitude/Offset and it is not loaded from the workspace correctly.
Please change under Options drop-down the Channel 1/2 Range to Amplitude.

You should enable the warnings.
Note thate the reference resistor value is not suitable for such capacitance and low frequency measurement. The impedance of DUT/Resistor is above 100dB, leading to inaccurate measurements.

WF v3.11.4

image.thumb.png.2cd1abf2c18c6c611aca33416ea93f56.png

WF v3.9.1

image.thumb.png.3df429a7376b2be54887dfffde847e69.png

 

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