Hi Arnaldo,

The time constant of CPE should not be constant, as the phase angle remains constant by definition. However, in some frequency level the amplitude should start to decrease. Your formula does not say anything about parasitic parameters as inductance and ESR. It seems to me that it is better to measure the impedance Bode plot and the cut-off frequency of your component. Having this experimental data, you can compose the proper calculation formula. Maybe, the component producer has the Bode plot already?

Best regards,

Jüri

Please note that at

cutoff frequency the

gain is .707 of the max.

This is due to the fact that

(.707)^2 is 1/2 and this is the

half power point.

This and more is in my book

The American University Laboratories For Electrical Engineering Part 1

I recommend using Micro-Cap (http://www.spectrum-soft.com/download/download.shtm). All EE's at Emerson used Micro-cap, even though it cost $4,000 each. There are no other electronic SPICE modeling programs even close to Micro-Cap capability.

Micro-Cap is now free. Andy Thompson, owner of Spectrum Software, has retired.

Micro-Cap does worst case analysis --- changing the tolerances of components --- changing the temperature --- etc. And it is easy to use.

I have used Micro-Cap for all of my electronic designs since 2001. When I tested prototypes, they worked exactly as the model predicted.

The website --- https://NDAcademy.FoxPing.com/ --- 2.8 Electronic Cascade RC Filters --- and --- 7.2 Electronic SPICE Models --- provide examples.