finding VGS value for diode connected MOSFET

Status
Not open for further replies.

kiransbaddi

Member level 2
Joined
Nov 30, 2015
Messages
51
Helped
0
Reputation
0
Reaction score
0
Trophy points
6
Activity points
427
please help me find the value of VGS

 

Hi,

I = ( V1 - V_gs) / 10k (calculated with the voltage across R which depends on V_gs)
And the mosfet has it's own characteristic.
I mainly depends on V_gs, but also on V_ds.

Now you have two I, both needs to be equal.
You can solve this mathematically or by drawing a chart.

Klaus
 

    V

    Points: 2
    Helpful Answer Positive Rating
You have the MOSFET inverted, so the MOSFET will conduct through the substrate diode.
Since you have the gate tied to the source the Vgs is zero.

For a diode-connected MOSFET you would invert the MOSFET with the gate still connected to V1.
In that case Vgs would be slightly above its threshold voltage.
 
As mentioned by crutschow, the substrate connection has to be corrected.

For a first order estimation, solve the idealized quadratic MOSFET equation.
 
Status
Not open for further replies.

Similar threads

Cookies are required to use this site. You must accept them to continue using the site. Learn more…