Question

When V_DS is the drain voltage and V_DS(max) is the maximum drain voltage, the JFET will breakdown if:
1. V_DS < V_DS(max)
2. V_DS = V_DS(max)
3. V_DS > V_DS(max)
4. V_DS = 0.25 V_DS(max)

Answer 1

Correct Answer - Option 3 : V_DS > V_DS(max)

Shorted-gate drain current (I_DSS): It is the drain current with source short-circuited to gate (i.e. V_GS = 0) and drain voltage (VDS) equal to pinch off voltage. It is sometimes called zero-bias current.

• I_DSS is measured under shorted gate conditions, it is the maximum drain current that we can get with normal operation of JFET.
• There is a maximum drain voltage [V_DS(max)] that can be applied to a JFET. If the drain voltage exceeds V_DS(max), JFET would breakdown.
• The region between V_P and V_DS(max) (breakdown voltage) is called the constant-current region or active region.