Analysis and design of an adaptive-supply class H audio power amplifier for mobile devices

Abstract

which operates with only single-rail supply. The supply to the output stage is designed to be adaptive to the instant input signal level so that the voltage drop across the power transistor is kept constant. Therefore, compared with other linear amplifier architectures (class B/AB/G), the proposed design features much better overall power efficiency. An existing issue with the above-mentioned adaptive-supply amplifiers is the additional distortions that occur during mode switching. For class G topology when the switching threshold is reached, the supply voltage sees step changes during the low to high transitions. These abrupt changes tend to add distortions to the outputs of the amplifier. Therefore, for conventional adaptive-supply amplifiers, there is a sudden burst in the Total Harmonic Distortion (THD) when the high supply starts operating. In this research, we proposed a common-mode modulation (CMM) scheme to resolve this problem. Instead of changing the system configuration upon the triggering of mode switching, the amplitude information of the input signal is extracted and embedded into the common-mode (CM) voltage of the vi

Power management integrated circuit in audio and low power applications

“…The controller stage consists of a differential difference amplifier (DDA) [56], a type III compensator, a feedforward op-amp, a pulse width modulator, and a soft-start circuit. All these circuits are part of the negative feedback loop, except for the soft-start circuit.…”