What class of amplifier is characterized by the bias set well beyond cutoff?

The class of amplifier characterized by the bias set well beyond cutoff is Class C. In Class C amplifiers, the operation occurs for less than half of the input signal cycle, which means they are biased heavily toward cutoff. This results in a very efficient amplifier that generates a significant amount of power for signals like radio frequency transmission but is not suitable for low distortion audio amplification due to the nonlinear characteristics associated with its operation.

Class C amplifiers are particularly favored in high-frequency applications because their efficiency can often exceed 75%. Their design allows them to be used in circuits that require high power and where signal distortion can be tolerated, such as in RF transmitters.

In contrast, Class A amplifiers operate in a linear region for the entirety of the signal cycle, Class B amplifiers conduct during half of the cycle, and Class AB lies in between, providing a balance of efficiency and linearity. Therefore, the distinction of Class C being set well beyond cutoff makes it unique compared to these other classes.