g:gate； S: source source; D: drain. N-channel power supply is generally connected to D, output S, and P-channel power supply is generally connected to S and output D, and the enhanced depletion connection is basically the same.
This is a MOS tube pyroelectric infrared sensor. The rectangular frame is the sensing window, the G pin is the grounding terminal, the D pin is the drain of the internal MOS tube, and the S pin is the source of the internal MOS tube. In the circuit, G is grounded, D is connected to the power supply, infrared signal is input from the window, and electrical signal is output from S.
It is judged that the gate GMOS driver mainly plays the role of waveform shaping and driving enhancement: if the G signal waveform of MOS transistor is not steep enough, it will cause a lot of power loss in the retrospective switching stage, and its side effect is to reduce the conversion efficiency of the circuit. MOS tubes are seriously heated and easily damaged by heat, and there is a certain capacitance between MOS tubes GS. If the driving ability of G signal is not enough, it will seriously affect the time of waveform jump.
Connect the G-S short circuit, select the multimeter R× 1, connect the black stylus to the S pole, and connect the red stylus to the D pole. The resistance should be above several ohms to ten ohms. If it is found that the resistance between one pin and its two pins is infinite, and it is still infinite after exchanging probes, it is confirmed that this pin is G-pole because it is insulated from the other two pins.
Judge the source S and the drain D. Set the multimeter at R× 1k to measure the resistance between the three pins respectively. Measure the resistance twice by exchanging pens and meters, and the one with lower resistance (generally thousands of ohms to more than 10,000 ohms) is the forward resistance. At this time, the black pen is the S pole, and the red pen is connected to the D pole. Due to different test premises, the measured RDS(on) value is higher than the typical value given in the manual.
As for MOS transistors, there are N channels, so they are called N-channel MOS transistors, or NMOS. There are also P-channel MOS(PMOS) transistors, which are lightly doped N-type back gates and P-type sources and drains.
The working principle of both N-type and P-type MOS transistors is essentially the same. The MOS transistor controls the current at the drain of the output terminal through the voltage applied to the gate of the input terminal. MOS transistor is a voltage-controlled device, and the characteristics of the device are controlled by the voltage applied to the gate, so there will be no charge storage effect caused by the base current of triode as a switch, so the switching speed of MOS transistor is faster than that of triode in switching application.
The name field effect transistor also comes from its input (called gate), which affects the current flowing through the transistor by projecting an electric field on the insulating layer. Actually, no current flows through this insulator, so the gate current of the FET is very small. The most common FET uses a thin layer of silicon dioxide as an insulator under the gate electrode.
This kind of transistor is called a metal oxide semiconductor (MOS) transistor, or a metal oxide semiconductor field effect transistor (MOSFET). MOS transistors have replaced bipolar transistors in many applications because they are smaller and more energy efficient.