BJTs, MOSFETs, and IGBTs serve as crucial semiconductor devices, each offering distinct characteristics and advantages suited to different applications.

The below table provides an overview of the difference between bipolar junction transistors (BJTs), MOSFET (Metal Oxide Semiconductor Field Effect Transistor) and IGBT (Insulated Gate Bipolar Transistor) transistors in their usage within power electronics:

What is BJT?

A bipolar junction transistors (BJTs)is a three-terminal semiconductor device and most used transistor type in electronic circuits. The operation of a Bipolar Junction Transistor (BJT) involves the control of the flow of charge carriers (electrons or holes) between the emitter, base, and collector.

The flow of current in a BJT is controlled by the injection of minority charge carriers (electrons in an NPN BJT and holes in a PNP BJT) from the emitter to the base region. In an NPN BJT, when a small current flows from the base to the emitter terminal, it controls a much larger current flowing from the collector to the emitter. In a PNP BJT, the direction of current flow is reversed.

Types of Bipolar Junction Transistors (BJT):

Bipolar junction transistors are available in two main types:

  • NPN (negative-positive-negative)
  • PNP (positive-negative-positive)

What is MOSFET?

A MOSFET, or Metal Oxide Semiconductor Field Effect Transistor, relies on the modulation of charge carriers in a semiconductor channel under the control of an electric field. When a voltage is applied between the gate and the source terminal, an electric field is created across the insulating layer, which modulates the conductivity of the semiconductor channel between the source and drain terminals.

  • In an n-channel MOSFET, a positive voltage applied to the gate terminal induces a conductive channel between the source and drain, allowing current to flow.
  • In a p-channel MOSFET, a negative voltage applied to the gate creates the conductive channel.

What is IGBT?

IGBT (Insulated Gate Bipolar Transistor), is a power semiconductor device that combines the high-speed switching capability of a MOSFET with the high-current handling capabilities of a BJT.

The operation of an IGBT involves the control of a high-power circuit using a small signal. When a voltage is applied to the gate terminal, it modulates the conductivity of the semiconductor channel between the collector and emitter terminals, allowing for the control of large currents.

Difference between BJT and MOSFET (BJT vs MOSFET)

Below is a comparison table outlining the key differences between Bipolar Junction Transistors (BJTs) and Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFETs):

Difference between IGBT and MOSFET (IGBT vs MOSFET)

Understanding the difference between IGBT and MOSFET provides a concise overview of the key differences based on their characteristics and capabilities.

Below is a comparison table outlining the key differences between Metal Oxide Semiconductor Field Effect Transistors (MOSFETs) and IGBT (Insulated Gate Bipolar Transistors).

Difference between IGBT and BJT (IGBT vs BJT)

The table provides an overview of the differences between IGBTs, and bipolar junction transistors (BJTs) based on their characteristics.

Applications of BJT, MOSFETs and IGBTs

Some of the applications of BJT, MOSFETs and IGBTs are:

Applications of BJT (Bipolar Junction Transistor):

  • Amplifiers: BJTs are commonly used in audio amplifiers, RF amplifiers, and other signal amplification applications due to their ability to amplify current.
  • Switching Circuits: They are used in various electronic switching circuits, such as pulse generators and digital logic circuits, where moderate switching speeds are acceptable.
  • Oscillators: BJTs are employed in the construction of oscillators, which generate periodic signals in electronic devices such as radios, televisions, and computers.

Applications of (Metal Oxide Semiconductor Field Effect Transistor):

  • Power Supplies: MOSFETs are widely used in switch-mode power supplies due to their ability to handle high frequencies and power levels efficiently.
  • Motor Control: They are utilized in motor control applications, such as in electric vehicles, industrial automation, and robotics, for their fast-switching speeds and high power handling capabilities.
  • Converters and Inverters: MOSFETs are integral components in DC-DC converters, AC-DC converters, and inverters for renewable energy systems and motor drives.

Applications of IGBT (Insulated Gate Bipolar Transistor):

  • Motor Drives: IGBTs are extensively used in variable speed motor control applications, such as in electric trains, elevators, and escalators, due to their ability to handle high currents and voltages.
  • Power Inverters: IGBTs are an essential component in power inverters for applications like solar energy systems, uninterruptible power supplies (UPS), and electric vehicles, where they facilitate the conversion of DC power to AC power.
  • Welding Equipment: IGBTs play a crucial role in modern welding machines, offering high current capability and fast switching to control the welding process effectively.