What is Class AB Amplifier – Features, Working & Applications

A class AB amplifier is a type of electronic amplifier that combines the advantages of class A and class B amplifiers. It is designed to provide high-quality audio amplification while minimizing power dissipation.

Class AB amplifiers use two transistors in the output stage, one of which conducts when the input signal is positive and the other conducts when the input signal is negative. The transistors are biased such that they are both slightly on when there is no input signal, reducing the crossover distortion that is common in class B amplifiers.

Features of Class AB Amplifier

  • Low distortion
  • High efficiency
  • Good sound quality
  • Cost-effective
  • Suitable for a wide range of applications

Working of Class AB Amplifier

Class AB Amplifier

Class AB amplifier works by using two or more transistors to amplify an audio signal. When there is no input signal, a small current flows through the transistors to reduce distortion. When an audio signal is present, the transistors are driven into a more active state, producing a more powerful output signal. The output signal is then filtered to remove unwanted noise or distortion before being sent to the load, such as a speaker. The key to its operation is biasing the transistors to maintain a high-quality output signal while still being relatively efficient.


The Class AB amplifier is commonly used in audio applications such as:

  • Home theater systems
  • Professional audio systems
  • Musical instruments
  • Stereo amplifiers
  • Portable audio devices
  • Car audio systems
  • Headphone amplifiers
  • DJ equipment

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