A class D switching power amplifier with high efficiency and wide bandwidth by dual feedback loops

The pulse width modulated class D power amplifier has the highest efficiency among various classes of amplifiers. However the performances, such as bandwidth, distortion and stability are inferior to those of the conventional class A or B. This paper presents a new class D amplifier employing dual feedback loops, namely current and voltage feedback considering complex impedances of the loudspeakers. The novel class D amplifier provides wide full-power bandwidth and stability at any load with high efficiency.