MOSFET switch IRF520

Discussion in 'General Electronics Chat' started by sa7her, Mar 21, 2011.

1. sa7her Thread Starter New Member

Oct 19, 2010
8
0
Hi,

Im planing to design a small switching circuit to find the i-v characterstic of the MOSFET IRF520. The circuit diagram can be found at the attachment.In my circuit Vdd= 12V and the current through the load resistor is 100mA. I will vary the input voltage from 0V to 5V to find when the mosfet will switch on or off and by the voltmeter I will find the load voltage ( Vl) and the current ( Il).

The datasheet for the MOSFET IRF520 can be found here :
http://www.datasheetcatalog.org/datasheet/fairchild/IRF520.pdf

all what I want to learn is how can i found the value for load resistor ( Rl) and the gate resistor ( Rg). I understand how the MOSFET work, I read alot about it but the thing that I couldnt found it is how to calculate the resistors values. What equation can I use.

I use this way to find the load resistor, is it correct?:

Code ( (Unknown Language)):
1.
2.
3. Vdd= Il * Rl
4. Vdd= 12V
5. Il=100mA
6.
7. so Rl = ( 12) / ( 100mA) = 120 OHMS
8.
9.

if it is correct, what about Rg. how can i find it. can I use a 1M resistor ?

Im waiting your replays.

Thanks alot

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