# How can I test a MOSFET for Zero Gate Voltage Drain Current on my curve tracer?

### 問題：

How can I test a MOSFET for Zero Gate Voltage Drain Current on my curve tracer?

### 答案：

Zero Gate Voltage Drain Current - IDSS

What It Is:

Zero gate voltage drain current is the ID that flows when VGS=0.  It’s the on-state current in a depletion mode MOSFET and the off-state current in an enhancement mode MOSFET.

On the iv curve tracer, the Collector Supply drives the drain and the gate is shorted to the source so that VGS=0.

What The Display Shows:

The display shows VDS on the horizontal axis, and the resulting ID on the vertical axis.  The specification is met when with VGS=0 and the specified VDS applied, ID is less than or equal to the specified maximum.

How To Do It:

1. Set controls:

A:Max Peak Volts to the lowest setting above the specified VDS

B: Max Peak Power Watts to the lowest setting that satisfies (ID x VDS)

C: Horizontal Volts/Div to display VDS between the 5th and 10th

horizontal divisions

D: Vertical Current/Div to display the ID between the 5th and 10th vertical divisions

E: Collector Supply Polarity to (+DC) for N-channel or (-DC) for P-channel

F: Configuration to (Base/Short, Emitter/Common)

G: Variable Collector Supply to minimum % (full ccw)

H: DotCursor ON

2. Apply power to the MOSFET:

A: Position the Left/Right switch as appropriate

B: Slowly increase the Variable Collector Supply % until the specified VDS is reached

3. Compare to data sheet specifications:

Check that at the specified VDS, ID is less than or equal to the specified maximum