IGBT vs MOSFET: What's The Difference?

IGBT vs Mosfet Image source: EtechnoG

Insulated Gate Bipolar Transistor(IGBT) and Metal Oxide Semiconductor Transistor (MOSFET) are two types of transistors used in various electronic devices.

While both are power semiconductor electronic components, there are some key differences between the, For example, they have different voltage and current capacities.

There are also some slight variations on their physical attributes.

Before you proceed to buy either of these transistors, it will be wise to have an in depth overview of them.

In this article, we are going to look at the differences between IGBT vs MOSFET. At the end , you will buy one that suits your application.

I will also give you tips on choosing the best semiconductors supplier in China, whether you want IGBT or a MOSFET.

Table of Contents

What is IGBT?

As we have already introduced, IGBT stands for Insulated Gate Bipolar Transistor. It is a type of power semiconductor designed to combine the key properties of MOSFET and BJT.

We call it a power semiconductor device because it is voltage-controlled. The voltage that is supplied at the gate of this transistor controls the flow of current throughout the device. This is a common feature that you will also find in MOSFET, only that this is a bipolar transistor meaning that it has the capacity to handle both the negative and positive currents while MOSFET is a unipolar device.

The design and make of IGBTs allow them to have high current capacities, not forgetting that they also tend to have fast switching speeds. The two kep properties make them applicable in high-power applications such as electric vehicles, energy systems among others.

Even though they have the same electrical properties, IGBTs come in different current and voltage ratings. This is vital as they are used in different applications that have different power ratings. So, pay attention to such technical details when buying IGBTs for sale.

What is MOSFET?

A Metal-Oxide Semiconductor Field-Effect Transistor (MOSFET) is another power transistor whose gate is made of metal-oxide-semiconductor (MOS) Just like the IBJTs, MOSFETs are voltage-controlled semiconductor devices. This implies that a defined voltage has to be applied at the gate terminal and it will be responsible for controlling the circuit throughout the device.

MOSFETs are widely used in both digital and analog circuits whereby the control the flow of current in their respective application areas.

They come in two major classes. n-channel ad p-channel with the latter being more popular. They also come in different voltage and current ratings. So, when buying one, ensure that it is suitable for your device or application area. Their packages also tend to vary.

How does IGBT work?

AN IGBT has three terminals which are the collector, the gate and the emitter. The collector and the emitter serves as the passage of current in and out of the transistor while the gate serves as a control terminal. An insulating gate separates the gate from the collector and emitter terminals.

When it comes to the actual operation of the IGBT, a small input current is applied at the gate terminal of the transistor. This small current will be responsible for controlling the larger current that is flowing between the collector and the emitter.

When a positive voltage is applied at the gate, it will create a stream of electrons between the collector and the emitter terminals. This will allow current to flow freely. When the supply voltage is disconnected from the gate terminal, the flow of current in the transistor will stop.

From the working formula, you can tell why IGBT is used for motor and power control applications.

How does a MOSFET work?

Like the IGBT, a MOSFET has three terminals which are the source, the drain and the gate terminals. Electrons flow between the source and the drain terminals.

The source and the drain terminals of a MOSFET transistor are located at the opposite sides of each other on the channel. The gate is positioned right above the channel.

A thin insulation layer secludes the gate terminate from the other two.

When a small amount of voltage is applied at the gate terminal, it will create an electric field which will subsequently create an electric field that will determine the movement of electrons. There will be a directional flow of current between the terminals.

A MOSFET is designed to be operated in two modes: enhancement and depletion modes.

In the enhancement mode, the transistor is off and there is no voltage supplied at the gate terminal The transistor will be turned ON when you supply the right amount of voltage at the gate terminal.

The depletion mode is when the MOSFET is turned on. There is a complete path between the drain and the source current. The gate terminal of the transistor is turned off when you apply the voltage.

Comparing IGBT vs MOSFET

Now that you know what these two transistors are and how they work, we can proceed their various features. From this comparison you will know which one to use and where to use.

Structure and design

This is the first comparison point between MOSFET vs IGBT. Just by looking at them, it will be difficult to spot the difference. They have the same design. In fact, you will need to have some level of expertise when it comes to distinguishing them.

The difference comes in the structural arrangement of the layers in both. IGBT features an extra layer of p substrate that is beneath the the n substrate. In this layer, holes tend to penetrate to the resistive n-layer hence causing an overflow of electron carriers. This ends up increasing the conductivity of the n-layer resulting to reduction of voltage in the IGBT.

However, this extra layer is also responsible for blocking the reverse current flow forcing the installation of an extra diode.

On the other hand, the structural arrangement of MOSFET is devoid of this minority carrier hence is capable of switching at high frequencies.

Still on the structural aspect, IGBT has a PN junction that is very conspicuous on its construction. On the other hand, MOSFET does not have the PN junctions.

Switching power

This is another area where MOSFET and IGBT tend to differ. We can define the switching power of a transistor as the maximum power that a tarnsistor is capable of handling while switching between the ON and OFF states. It is also referred to as the conduction loss or the dissipated power.

IGBT has a slower switching speed than MOSFET. This means that its switching power is also relatively lower. This feature alone makes MOSFETs applicable for high-power applications.

However, ensure that switching power of a capacitor does not exceed its rated power as this can cause overheating. At the same time, the operation power should be kept within the safe operation area. (SOA).

Keep in mind that there is a close relationship between the switching power and switching speed. The higher the switching power, the higher the speed. This explains why MOSFET has a higher switching speed than IGBT.

Turn Off time

The turn off time of a transistor refers to the time that it takes for a transistor to switch between the states (usually On and Off). This time is measured in nanoseconds and sometimes in microseconds. This time is usually determined by the physical and electrical properties of a transistor.

MOSFET has a faster turn-off time than IGBT. This explains why it is more suitable for the high-frequency applications. The faster turn-off time for MOSFETs also makes it suitable for the sensitive applications.

Voltage and current characteristics

IGBT and MOSFET also have some major disparities when it comes to their voltage and current properties.

When it comes to voltage and current capacity, IGBT is capable of handling more voltage and current than MOSFET, which is ideal for the medium and low voltage.

Also, IGBT is capable of handling transient voltage and current while MOSFET does not have such capacity.

IGBT has a low forward voltage drop than MOSFET

Application areas and cost

IGBT is a perfect transistor for the high-power AC applications such as power inverter circuits. On the other hand, MOSFET is ideal for the low power DC applications such as residential power systems.

In terms of cost, IGBT is more expensive than MOSFET.

Conclusion

At this point, you know the differences between insulated gate bipolar transistors and Metal-oxide semiconductor field-effect transistors.

Now you know which one to use and how it will be relevant to your application.

As we have already mentioned, you should take extra precautions when buying these power electronic components. Focus on buying quality and genuine products.

The surest way of achieving this goal is by buying from a reputable and reliable supplier in China.

And this is where ICRFQ comes in. We are reputable transistor supplier in China.

Our main task is to source for the quality electronic components and deliver to our clients.

If you want to buy IGBTs and MOSFETs in China, consider contacting us directly for help.

We are experts in the industry and will do all that it takes to deliver.