Define crossover distortion in Class B amplifier configurations.
1 Answer
Crossover distortion is a type of distortion that occurs in Class B amplifier configurations, which are designed to amplify signals using a push-pull arrangement of complementary transistors. In a Class B amplifier, one transistor handles the positive half of the input signal, while the other handles the negative half.
The primary objective of a Class B amplifier is to minimize power dissipation when there is no input signal (idle state). This is achieved by biasing the transistors so that they are turned off when there is no input, reducing wasted power.
However, this biasing arrangement creates a problem known as crossover distortion. This distortion occurs when the input signal transitions from the positive half to the negative half (or vice versa), and the control of the two transistors switches from one to the other. At this point, both transistors are momentarily turned off, causing a gap or distortion in the amplified output signal.
The crossover distortion can create a notch or a dead zone around the zero-crossing point of the input signal. This distortion is typically unwanted in audio amplification, as it introduces harmonic components that were not present in the original signal, leading to an audible degradation in sound quality.
To mitigate crossover distortion, additional circuitry can be introduced, such as using Class AB or Class AB push-pull amplifier configurations. These configurations slightly bias the transistors into conduction, even when there is no input signal, to ensure that the transition between the positive and negative half of the signal is smoother and without any significant gap. The result is reduced crossover distortion and improved audio fidelity.
The primary objective of a Class B amplifier is to minimize power dissipation when there is no input signal (idle state). This is achieved by biasing the transistors so that they are turned off when there is no input, reducing wasted power.
However, this biasing arrangement creates a problem known as crossover distortion. This distortion occurs when the input signal transitions from the positive half to the negative half (or vice versa), and the control of the two transistors switches from one to the other. At this point, both transistors are momentarily turned off, causing a gap or distortion in the amplified output signal.
The crossover distortion can create a notch or a dead zone around the zero-crossing point of the input signal. This distortion is typically unwanted in audio amplification, as it introduces harmonic components that were not present in the original signal, leading to an audible degradation in sound quality.
To mitigate crossover distortion, additional circuitry can be introduced, such as using Class AB or Class AB push-pull amplifier configurations. These configurations slightly bias the transistors into conduction, even when there is no input signal, to ensure that the transition between the positive and negative half of the signal is smoother and without any significant gap. The result is reduced crossover distortion and improved audio fidelity.