What Is a MOSFET Transistor?

Metal-Oxide Semiconductor Field-Effect Transistor (Metal-Oxide-Semiconductor Field-Effect Transistor, MOSFET) is a field-effect transistor that can be widely used in analog and digital circuits. ). ^[1] MOSFETs can be divided into two types: "N-type" and "P-type" according to the polarity of their "channels" (working carriers). , PMOS, etc.

MOSFET

Metal-Oxide Semiconductor Field-Effect Transistor (Metal-Oxide-Semiconductor Field-Effect Transistor, MOSFET) is a field-effect transistor that can be widely used in analog and digital circuits. ). ^[1]

Figure 1 shows a typical planar N-channel enhancement mode NMOSFET.

For the enhanced N-channel MOSFET to work, a positive value must be added between G and S.

There are many parameters of the field effect tube, including DC parameters, AC parameters and limit parameters, but the following main parameters are concerned when generally used:
1. IDSSsaturated drain-source current. It refers to the drain-source current in the junction or depletion type insulated gate field effect transistor when the gate voltage UGS = 0.
2. UPPinch off voltage. It refers to the gate voltage of the junction or depletion type insulated gate field effect transistor immediately after the drain-source is turned off.
3. UTOpening voltage. It refers to the gate voltage when the drain-source is just turned on in the reinforced insulated gate field effect transistor.
4. gMtransconductance. It is the gate-to-source voltage UGSthe ability to control the drain current ID, that is, the ratio of the change in the drain current ID to the change in the gate-source voltage UGS. gM is an important parameter to measure the amplification ability of the FET.
5. BUDSDrain-source breakdown voltage. It refers to the maximum drain-source voltage that the field effect tube can withstand when the gate-source voltage UGS is constant. This is a limit parameter. The working voltage applied to the FET must be less than BUDS.
6. PDSMMaximum power dissipation. It is also a limit parameter, which refers to the maximum drain-source dissipation power allowed when the performance of the FET is not deteriorated. When used, the actual power consumption of the FET should be less than PDSM and leave a certain margin.
7. IDSMMaximum drain-source current. It is a limit parameter, which refers to the maximum current allowed between the drain and the source when the field effect tube works normally. The working current of the FET should not exceed IDSM.

Over the past decades, the size of MOSFETs has continued to decrease. In the early integrated circuit MOSFET process, the channel length was on the order of several micrometers. But in today's integrated circuit manufacturing process, this parameter has been reduced by dozens of times or even more than one hundred times. In early 2006, Intel began to use 65 nanometer (nanometer) technology to manufacture a new generation of microprocessors. The actual component channel length may be smaller than this number. By the end of the 1990s, the size of MOSFETs continued to shrink, which greatly improved the efficiency of integrated circuits. From a historical perspective, these technological breakthroughs are closely related to the progress of semiconductor processes.

In theory, the gate of the MOSFET should be a conductor with good electrical properties as much as possible. The polysilicon after heavy (read as zhong) doping

Double-gate MOSFET

Dual-gate MOSFETs are commonly used in radio frequency (RF) integrated circuits. Both gates of this MOSFET can control the current. in

Power MOSFET stands for Power Field Effect Transistor. Its three poles are the source (S), the drain (D), and the gate (G). Main advantages: good thermal stability and large safe working area. Disadvantages: low breakdown voltage and small working current. IGBT stands for Insulated Gate Bipolar Transistor. It is a combination of MOSFET and GTR (power transistor). Its three poles are the collector (C), the emitter (E), and the gate (G). Features: The breakdown voltage can reach 1200V, and the maximum saturation current of the collector has exceeded 1500A. The inverter with IGBT as the inverter device has a capacity of more than 250kVA and an operating frequency of 20kHz.