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I need to use the best model for the MOSFET in my circuit I'm simulation on PSIM, the MOSFET is Si4108-TI-GE3.

But I am not given the parasitic capacitance values (Cgs Cds Cdg), I am only given this:

dynamic charge characteristics of the capacitor to be modeled

I think I should use Q=CU, but I don't see how to use Q=CU for Cds since I only have Total gate charge and I don't know if that is the drain-source charge. How do I calculate the necessary parasitic capacitance values?

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  • \$\begingroup\$ Generally, Q=CV \$\endgroup\$
    – Eugene Sh.
    Jun 17 '15 at 15:55
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Read the data sheet: -

enter image description here

Ciss is gate-source capacitance. You should be able to work out the other two.

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I realize that I am very late to the party but the question remains unanswered.

Cgd = Crss

Cgs = Ciss - Crss

Cds = Coss - Crss

You'll need to pick the values at the operating conditions you are working at.

This video should give some ideas https://youtu.be/iATO3mUKBPc

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The capacitances vary significantly with voltage so it's not so easy. (A different MOSFET)

enter image description here

Here is a SPICE model for the si4108:

enter image description here

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