Which amplifier class is typically used in high-efficiency applications due to its low power dissipation?

Class C amplifiers are designed specifically for high-efficiency applications and are characterized by their low power dissipation. This is primarily because Class C amplifiers conduct for less than half of the input signal cycle, which minimizes the time during which they are active. Their operation in saturation allows for high efficiency, typically exceeding 70%, making them ideal for situations where power efficiency is paramount, such as in RF transmission.

In contrast, Class A amplifiers have a much lower efficiency, often around 20-30%, as they conduct for the entire input cycle and dissipate a lot of power as heat. Class B amplifiers improve upon this with a theoretical maximum efficiency of about 78.5% by using two devices that conduct each for half of the cycle, but they are still not as efficient as Class C. Class AB is a compromise between Class A and Class B, providing a balance of efficiency and linearity but still underperforming compared to Class C in terms of power efficiency.

Given these characteristics, Class C amplifiers are utilized in applications such as radio frequency (RF) transmission, where high efficiency is crucial, thereby making them the preferred choice in these scenarios.