How to distinguish whether MOS tube is N-channel or P-channel?

1. How to judge the three poles of MOS?

The key points should be grasped in the identification of the three feet on the MOS diode symbol.

G pole, needless to say, is easier to recognize. S-pole, whether it is P-channel or N-channel, is where two lines intersect. The D-pole, whether it is a P-channel or an N-channel, is the side of a single lead.

2. How to distinguish whether the FET is N-channel or P-channel?

A: In the circuit diagram, the arrow of the N-channel MOS diode points inward, and the arrow of the P-channel points outward.

The measurement method of N-channel is: the multimeter is set to diode, the red stylus is connected to the S pole, and the black stylus is connected to the D pole. It can be judged that this MOS diode is N-channel when the resistance value is measured to 400 to 800. The measurement method of the P-channel is: the multimeter is set to the diode position, the red stylus is connected to the D pole, and the black stylus is connected to the S pole. When the resistance of 400-800 is measured, it can be judged that this MOs diode is P-channel.

A set of values (600-800) of the S and D poles are measured with a probe diode. Red S, black D, N-channel black S, and red D, P-channel.

3. How to determine the direction of parasitic diode?

Next, it is the direction judgment of parasitic diode:

Its judgment rule is: n channel, from s pole to d pole; P-channel, from D-pole to S-pole.

Regardless of the N-channel or P-channel MOS transistor, the arrow direction of the intermediate substrate and the arrow direction of the parasitic diode are always the same: either both point from S to D or both point from D to S..