You are given a blackbox with four terminals The blackbox de

You are given a black-box with four terminals. The black-box definitely contains an n-channel MOSFET.

a. What will be your strategy to identify the Gate terminal using only a DMM?

b. What will be your strategy to identify the Bulk terminal using only a DMM

c. For all MOSFETs, using a DMM only, is it possible to differentiate between the Source and Drain? If yes, what will be your strategy to differentiate between Source and Drain? If no, why not?

Solution

what is going on it\'s straight forward to determine the package pins. Note the gate will be a capacitor and the S-D connection is a diode.

Digital Multi-meter set in diode mode. Pick a pin with one probe, and then probe one of the remain other ones.

1) If it reads a diode (but doesn\'t change) then you have found S and drain right away. Other pin is gate.

2) if it reads open (and doesn\'t drift) then you have found S and D right away but in reverse bias. Switch leads on pins and follow instruction from #1.

3) If you can\'t get a stable reading then one of your probes is on the gate is the meter is slowly charging the gate capacitance. Change one of the leads and then the other until you see either 1 or 2.