what if gate is connected with source in nMOS transistor

[Rahul Sharma]

what is the use of this connection in any circuit. i think it will always be in cut off mode.

& how to make a nMOS to work as a current source?

 

[Audioguru]

A Jfet can be used as a current source when its gate is connected to its source. Because a Jfet has depletion mode and conducts its maximum current when Vgs is zero..
A Mosfet cannot be used because it has enhancement mode.

 

[Rahul Sharma]

A Jfet can be used as a current source when its gate is connected to its source. Because a Jfet has depletion mode and conducts its maximum current when Vgs is zero..
A Mosfet cannot be used because it has enhancement mode.

Thanks for providing clarification.
At this moment my next question would be "if i want a current source in my circuit and i want to make it using MOS only thn what should i do????

 

[FvM]

If it's an IC design problem (number of utilized transistors not important), review the bandgap reference chapter in your favourite analog IC design text book.

Enhancement MOSFETs (negative Vth) are possible, but not widely used.