Which class of amplifier provides the highest efficiency?

Class C amplifiers are known for providing the highest efficiency among the various amplifier classes. The efficiency of an amplifier refers to how well it converts input power into output power without excessive heat generation. Class C amplifiers operate with the transistor conducting for less than half of the input signal cycle, which allows for significant power savings. This is especially beneficial in applications such as RF transmission, where high efficiency is necessary to maximize output power while minimizing heat and power loss.

In practical terms, Class C amplifiers can achieve efficiencies exceeding 80% or even up to 90% in some designs, greatly surpassing Class A, which typically achieves only about 20-30% efficiency due to continuous conduction and higher heat generation. Class B amplifiers improve on the efficiency of Class A but still do not reach the high levels of Class C, as they operate with the transistor alternating conduction but still have some power losses. Class AB amplifiers are designed to bridge the gap between Class A and Class B by reducing crossover distortion, which slightly compromises their efficiency compared to Class C.

Overall, the operational characteristics and conduction strategy of Class C amplifiers distinctly contribute to their high efficiency in converting DC power to RF output power.