High efficiency class AD audio amplifier for a wide range of input signals

The combination of analog and switching techniques gives rise to an audio amplifier capable of producing low distortion with high efficiency. The inverter provides the power and the analog amplifier acts as an active filter creating an amplifier with overall good performance. Audio systems must exhibit good performance for a wide range of input signals in order to achieve high efficiency. In this paper, unipolar PWM control with dead-band is proposed as a technique to control the inverter, with the benefit of improving efficiency for low amplitude signals. The dead-band ensures that the inverter doesn't operate for low-amplitude signals, avoiding unnecessary switching losses for low volume operation. Simulation results and comparisons with alternative techniques are provided.