Which class of amplifier is defined by the presence of output throughout the entire signal cycle?

The class of amplifier characterized by output throughout the entire signal cycle is known as Class A. In a Class A amplifier, the output transistors conduct current for the entire 360 degrees of the input signal cycle, allowing for continuous amplification. This results in a linear response and minimal distortion, making Class A amplifiers ideal for high-fidelity audio applications.

In contrast, other amplifier classes have different characteristics. For example, Class B amplifiers conduct for half of the signal cycle (180 degrees), hence they turn off during the other half, leading to non-linear performance. Class C amplifiers operate even less than half of the cycle and are primarily used in RF applications where efficiency is more critical than linearity. Class AB amplifiers attempt to combine the benefits of Class A and Class B by conducting for slightly more than half the signal cycle, which enhances efficiency while still providing a linear output, but they do not maintain continuous output throughout the entire cycle as Class A does.