Calulating gate capacitance other parameters of mosfet from datasheet

Thread Starter

aamirali

Joined Feb 2, 2012
412
I have to calculate gate cap, now I got two methods, one is by looking at Vgs vs Qg graph & directly calculate Cgate = Qg/Vgs.
Second is finding separately Cgs & cgD & then adding them.
Problem is both gives two different results.

Plz suggest me some links or application notes where I can calculate these parameters from mosfet datasheet.
 

PaulEE

Joined Dec 23, 2011
423
I have to calculate gate cap, now I got two methods, one is by looking at Vgs vs Qg graph & directly calculate Cgate = Qg/Vgs.
Second is finding separately Cgs & cgD & then adding them.
Problem is both gives two different results.

Plz suggest me some links or application notes where I can calculate these parameters from mosfet datasheet.
I would apply a signal between the gate and source/drain and look at the RC-like curve you get. You know the equation that describes the curve...

Also, with your two methods, the current through the device causes the capacitance to vary. Does the spec sheet tell you under what conditions the graph was drawn?
 

Thread Starter

aamirali

Joined Feb 2, 2012
412
there any many factors which effects these parameters. I have VGS=10V, & need a current of 1A.
Is there any specific AN explaining how to calculate all the parameters by looking at mosfet datasheet
 
Top