Diode capacitance and Drain to Source capacitance in function of the frequency

Question

I m trying to determine what is the biggest parallel capacitor between a P-CHANNEL MOSFET and a diode. The datasheet give the diode capacitance @ 1 MHz and the different capacitors into the MOSFET @ 1 MHz. The drain to source capacitance is equal to Coss-Crss. Nevertheless, I do not kow how the capacitor into the diode and the MOSFET evolve in function of the frequency. It may decrease for the diode and it may increase for the MOSFET. I would like to determine the two parallel capacitances for each components at a frequency around 50 kHz - 100 KHz. Here are the datasheets:

https://www.infineon.com/dgdl/Infineon-BSS84P-DS-v02_07-en.pdf?fileId=db3a304330f68606013118ac7a9b4549 https://www.vishay.com/docs/88959/byg22a.pdf

Thank you very much !

Answer 1

Just look in the respective data sheets: -

I do not know how the capacitor into the diode and the MOSFET evolve in function of the frequency

You can rely on the capacitance values above for up to 1 MHz but gradually, as frequency rises you will get inductive properties of the devices coming into play and the data sheets are pretty lean in this respect.

As usual, my best advice is get models of them both and do some simulations.

I would like to determine the two parallel capacitances for each components at a frequency around 50 kHz - 100 KHz.

I believe you can trust the above graphs at those frequencies. The MOSFET appears to have lower capacitance than the diode.