Class-D audio amplifiers in mobile applications

A comparative system-level overview is given of alternative class-D amplifier architectures. The theory behind pulse-width modulation and different modulation schemes is discussed. Topological alternatives such as open-loop versus feedback, fixed-carrier versus self-oscillating are analyzed and compared in terms of relevant characteristics such as distortion, power supply rejection, efficiency and electro-magnetic interference. The combination of D/A conversion and class-D amplifiers is discussed.