In terms of signal fidelity, which class of amplifier generally produces the highest quality output?

Class A amplifiers are known for their high signal fidelity, characterized by their ability to produce a linear and clean output with minimal distortion. This is primarily due to the design of Class A amplifiers, which operates by conducting over the entire range of the input signal. They have a high quiescent current, meaning they are always on and ready to amplify the signal, which helps maintain linearity throughout the amplification process.

Because Class A amplifiers do not switch off during the parts of the signal cycle, they avoid the crossover distortion that often plagues other classes of amplifiers, such as Class B and Class C. Consequently, they can replicate the input signal with a high degree of accuracy, making them ideal for applications where fidelity is paramount, such as in high-end audio equipment.

While Class AB amplifiers do provide a good balance of efficiency and fidelity, they can still introduce some crossover distortion, although less than Class B amplifiers. Class C amplifiers are designed primarily for efficiency and are typically used in applications such as RF transmission, where fidelity is less critical. Therefore, Class A amplifiers are recognized for delivering the highest quality output among the amplifier classes.