What is the difference between MOSFET and IGBT? Olukey will answer your questions!

As switching elements, MOSFET and IGBT often appear in electronic circuits. They are also similar in appearance and characteristic parameters. I believe many people will wonder why some circuits need to use MOSFET, while others do. IGBT?

What's the difference between them? Next, Olukey will answer your questions!

What is a MOSFET?

MOSFET, the full Chinese name is metal-oxide semiconductor field effect transistor. Because the gate of this field effect transistor is isolated by an insulating layer, it is also called an insulated gate field effect transistor. MOSFET can be divided into two types: "N-type" and "P-type" according to the polarity of its "channel" (working carrier), usually also called N MOSFET and P MOSFET.

The MOSFET itself has its own parasitic diode, which is used to prevent the MOSFET from burning out when VDD is over-voltage. Because before the overvoltage causes damage to the MOSFET, the diode reversely breaks down first and directs the large current to the ground, thereby preventing the MOSFET from being burned out.

What is IGBT?

IGBT (Insulated Gate Bipolar Transistor) is a compound semiconductor device composed of a transistor and a MOSFET.

The circuit symbols of IGBT are not unified yet. When drawing the schematic diagram, the symbols of triode and MOSFET are generally borrowed. At this time, you can judge whether it is IGBT or MOSFET from the model marked on the schematic diagram.

At the same time, you should also pay attention to whether the IGBT has a body diode. If it is not marked on the picture, it does not mean that it does not exist. Unless the official data specifically states otherwise, this diode is present. The body diode inside the IGBT is not parasitic, but is specially set up to protect the fragile reverse withstand voltage of the IGBT. It is also called FWD (freewheeling diode).

The internal structure of the two is different

The three poles of MOSFET are source (S), drain (D) and gate (G).

The three poles of IGBT are collector (C), emitter (E) and gate (G).

An IGBT is constructed by adding an additional layer to the drain of a MOSFET. Their internal structure is as follows:

The application fields of the two are different

The internal structures of MOSFET and IGBT are different, which determines their application fields.

Due to the structure of MOSFET, it can usually achieve a large current, which can reach KA, but the prerequisite voltage withstand capability is not as strong as IGBT. Its main application areas are switching power supplies, ballasts, high-frequency induction heating, high-frequency inverter welding machines, communication power supplies and other high-frequency power supply fields.

IGBT can produce a lot of power, current and voltage, but the frequency is not too high. At present, the hard switching speed of IGBT can reach 100KHZ. IGBT is widely used in welding machines, inverters, frequency converters, electroplating electrolytic power supplies, ultrasonic induction heating and other fields.

Main features of MOSFET and IGBT

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

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

The ideal equivalent circuit of IGBT is shown in the figure below. IGBT is actually a combination of MOSFET and transistor. MOSFET has the disadvantage of high on-resistance, but IGBT overcomes this shortcoming. IGBT still has low on-resistance at high voltage. .

In general, the advantage of MOSFET is that it has good high-frequency characteristics and can operate at a frequency of hundreds of kHz and up to MHz. The disadvantage is that the on-resistance is large and the power consumption is large in high-voltage and high-current situations. IGBT performs well in low frequency and high power situations, with small on-resistance and high withstand voltage.

Choose MOSFET or IGBT

In the circuit, whether to choose MOSFET as the power switch tube or IGBT is a question that engineers often encounter. If factors such as the voltage, current, and switching power of the system are taken into consideration, the following points can be summarized:

People often ask: "Is MOSFET or IGBT better?" In fact, there is no good or bad difference between the two. The most important thing is to see its actual application.

If you still have questions about the difference between MOSFET and IGBT, you can contact Olukey for details.

Olukey mainly distributes WINSOK medium and low voltage MOSFET products. Products are widely used in military industry, LED/LCD driver boards, motor driver boards, fast charging, electronic cigarettes, LCD monitors, power supplies, small household appliances, medical products, and Bluetooth products. Electronic scales, vehicle electronics, network products, household appliances, computer peripherals and various digital products.