Hello,
1) as written in the datasheet LDC1000 the inductance is calculated with the formula:
L=1/[C*(2*pi*fsensor)^2]
I assume that the resonant circle is swinging at resonant frequency and this frequency is measured by LDC1000. Knowing the resonant frequency the formula is used to calculate inductance L. Nonetheless I observed a dependcy between Rp and L. By changing the Rpmin and Rpmax setting, inductance is changing. How is this possible? According to the L formula there is no dependency or does it mean, that the resonant frequency of the resonant circle is changing? In my opinion this cannot be the reason because I did not change anything except the boundary of Rp.
2) In addition to that I would like to know how the LC resonant circle is supplied with energy? I assume that the resonant circle is powered by a short step voltage with a fixed frequency(e.g.120 kHz much lower than LC resonant frequency). The amplitude can be set in the preferences. After power supply the LC circuit is swinging at resonant frequency. Am I right? Please correct me if I am wrong.
If I supply the LC circuit with e.g a sine wave, the LC circuit cannot swing at resonant frequency?! Therefore I think the voltage supply is a short step function.
Thanks for your help.
Jo