What is the difference between MOS tube and IGBT tube?

Power switching devices play a vital role in modern electronic devices and power systems. As two common power switching devices, MOS tube (metal oxide semiconductor field effect transistor) and IGBT tube (insulated gate bipolar transistor), MOS tube and IGBT tube are similar in shape and characteristic parameters, so why some circuits Use MOS tube? And some circuits use IGBT tubes? They have some important differences in performance and application. This article will delve into the differences between MOS tubes and IGBT tubes to help readers better understand the characteristics and applicable scenarios of these two devices.

What is a MOS tube?

There are two main types of field effect transistors, namely junction field effect transistor (JFET) and insulated gate field effect transistor (MOS transistor).

MOS tube is MOSFET, the full name of the Chinese metal - oxide semiconductor field effect transistor, due to the gate of this field effect tube is isolated by the insulating layer, so it is also known as the insulated gate field effect tube.

MOSFET can be divided into N-channel depletion type and enhancement; P-channel depletion type and enhancement of four categories.

Some MOSFETs will have a diode inside, which is a body diode, or a parasitic diode, or a continuity diode.

Regarding the role of parasitic diodes, there are two explanations:

• The parasitic diode of the MOSFET is used to prevent the MOS tube from being burned out under the condition of VDD overvoltage, because before the overvoltage causes damage to the MOS tube, the diode reversely breaks down first, and the large current is directly connected to the ground, thereby avoiding MOS The tube was burned out.
• Prevent the MOS tube from being burned when the source and drain of the MOS tube are reversely connected, and also provide a path for the reverse induced voltage when the circuit has a reverse induced voltage, so as to avoid the breakdown of the MOS tube by the reverse induced voltage .

MOSFET has the characteristics of high input impedance, fast switching speed, good thermal stability, and voltage-controlled current. In the circuit, it can be used as an amplifier, electronic switch, etc.

What are IGBTs?

IGBT (Insulated Gate Bipolar Transistor), an insulated gate bipolar transistor, is a composite semiconductor device composed of a transistor and a MOS transistor.

As a new type of electronic semiconductor device, IGBT has the characteristics of high input impedance, low power consumption under voltage control, simple control circuit, high voltage resistance, and large current, and has been widely used in various electronic circuits.

The body diode inside the IGBT is not parasitic, but is specially set to protect the fragile reverse withstand voltage of the IGBT, also known as FWD (freewheeling diode).

It is not difficult to judge whether there is a body diode inside the IGBT. You can use a multimeter to measure the C pole and E pole of the IGBT. If the IGBT is good and the resistance values measured at the C and E poles are infinite, it means that the IGBT has no body diode.

IGBT is very suitable for applications such as AC motors, frequency converters, switching power supplies, lighting circuits, traction drives and other fields.

Generally speaking, the advantage of MOSFET is that it has good high-frequency characteristics, and the operating frequency can reach hundreds of kHz and upper MHz. The disadvantage is that the on-resistance is large and the power consumption is large in high-voltage and high-current situations; while IGBT is used in low-frequency and high-power situations. Under the excellent performance, its on-resistance is small, and its withstand voltage is high.

MOSFET is used in switching power supply, ballast, high frequency induction heating, high frequency inverter welding machine, communication power supply and other high frequency power supply fields; IGBT is concentrated in welding machine, inverter, frequency converter, electroplating electrolysis power supply, ultra Audio induction heating and other fields

All in all, MOS tubes and IGBT tubes are two common power switching devices, each with different characteristics and applicable scenarios. MOS tubes perform well in low-voltage, low-power applications, while IGBT tubes have better performance in high-voltage, high-power applications. Understanding these differences will help engineers and electronics enthusiasts make informed decisions when designing and selecting power switching devices to meet the needs of a specific application. Whether it is a MOS tube or an IGBT tube, they provide important support for the efficient operation and reliability of the electronic system, and promote the development of modern technology.

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