Electronics - Field Effect Transistors (FET) - Discussion

Option D is correct.

In according to the JFET graph,

1.Linear region
2.Pinch off region
3.Cutt off region

1.Linear region - Gate source voltage increases the drain current also increases.
2.Pinch off region - In which gate-source voltage, the drain current become zero the voltage is known as pinch off.
3.Cutt off region - After the pinch-off region the gate is not dependent the gate-source voltage.

The pinch-off voltage for an N-channel JFET is 4V. When VGS=1V, lVDS(min)l at which pinch-off occurs is equal to

*N-type JFET is operated with VGS<=0; (i.e., reverse gate to source).
* VGS controls ID.

When VGS=0, IDSS=maximum current.
Assuming, initially, VGS=0;

Option A:

Now if we decrease VGS (more negative), then ID decreases; (Option A is correct only if we are given assumption " Assuming, initially, VGS=0;". Note, A and B are giving same meaning if this assumption is not considered.)

Option B:

Increasing VGS(greater than 0), will not increase current as N-channel JFET requires negative VGS for its operation (and thus for to be in constant current region for any VGS.)
Option C and D cannot be correct as VGS controls ID. In constant-current region, current is constant wrt VDS and not VGS.