Which class of amplifier has an operating angle of more than 180 degrees but less than 360 degrees?

The class of amplifier that operates with an angle of more than 180 degrees but less than 360 degrees is known as Class AB. In Class AB operation, the amplifier conducts over more than half of the input signal cycle, allowing for improved efficiency compared to Class A amplifiers, while still maintaining low distortion levels that are favorable for audio applications.

Class AB combines characteristics of both Class A and Class B amplifiers. It typically operates in a way where two transistors are used to handle the positive and negative halves of the signal. Each transistor conducts for a little more than half but less than the entire cycle, hence the angle of operation is between 180 and 360 degrees. This allows Class AB amplifiers to achieve better efficiency than Class A while providing better linearity and fidelity than Class B.

This design makes Class AB amplifiers particularly suitable for audio applications, providing a balance between performance and power efficiency.