Related to capacitance

[oly]

what is the relation between drain voltage and capacitance and also in gate voltage and capacitance?

 

[Venkadesh_M]

What capacitance ? gate capacitance ? in FET? MOSFET? IGBT?

 

[oly]

in simple nmos-
relation between drain capacitance and drain voltage
relation between drain capacitance and gate voltage

 

[pplus]

WIKI !!!! :bang:
https://en.wikipedia.org/wiki/Power_MOSFET

 

[oly]

I test nmos in hspice and i found that
drain voltage is inversly proportional to capacitance and gate capacitance is directly proportional to capacitance?
Is the analysis correct or not?

 

[betwixt]

capacitance is directly proportional to capacitance?

That makes sense! :grin:

Brian.

 

[oly]

its very obvious typing mistake sorry for that, I test nmos in hspice and i found that
drain voltage is inversly proportional to capacitance and gate voltage is directly proportional to capacitance?
Is the analysis correct or not?
Now can you give me the answer?

 

[Venkadesh_M]

take a capacitor of 10uF and charged for 10V. what will happen if the capacitance reduced to 1uF ? ? ?

 

[pplus]

Capacitance is determined by voltage, not otherwise.

where

\[CGD = \frac{1}{\frac{1}{AGD\sqrt{\frac{qeN }{2VGD}}} + \frac{1}{CoxD}}\]

so capacitance is directly proportional square root of gate drain voltage

 

[Venkadesh_M]

C = q / V

In any cap if capacitance reduces voltage will increase.

 

[pplus]

The voltage causes an outflow of charge carriers, which is equivalent to an increase in dielectric thickness and reduced capacity.;-)