i am a bit confused if we consider that the frequency is 40 Mhz and L=18uH wher c=33pF and if we consider the DATAx = 1 and the CHx_FIN_SEL=b01. the calculation as folows:

Fsensor =(CHx_Fin_Sel*Frefx*DATAx)/2^28

=(2 * 40*10^6 * 1)/2^28 =0.298 is it correct?

and

Csensor= 1/(L * (2*pi*Fsensorx)^2) - C

= 1/( 18 * 10^-6 *(2 * pi * 0.298)^2) - 33 pF is it correct?

Can you clarify if you are using the FDC2114 or the FDC2214? If you are using the FDC2114 (like you've tagged in your post), then you are using the wrong equation in your calculations above. You've used equation 9, which is only applicable to the FDC2214. You would need to use Equation 8.

Also please note that a DATAx value of 1 is not possible, because 0.298Hz is lower than the 10kHz sensor frequency minimum. You will get much more reasonable numbers if you use a sample DATAx value from the GUI.

If you are using an external 40MHz oscillator (the default on the EVM) and you have configured the CH0_FIN_DIVIDER to 2, then yes, those are the correct values to use in the equation.