Abstract: An apparatus and method are provided for a Class G amplifier that includes an output stage, where an output stage supply voltage is selected based upon an input signal voltage of the output stage. The amplifier may also include an input stage coupled to the output stage, where the input stage generates the input signal voltage for the output stage. The output stage may include first and second MOS devices operating as a Class AB amplifier, and the output stage supply voltage selected based upon gate voltages of the MOS devices. The supply voltages may be generated by a buck converter, and a charge pump that is coupled to the buck converter.

Abstract: An input stage for an audio power amplifier is provided. The input stage includes a fully differential amplifier and a supply-independent reference voltage generator. The supply-independent reference voltage generator provides a supply-independent reference voltage that is used as the common mode voltage of the output of the fully differential amplifier.

Abstract: A fully differential class D amplifier is provided. The class D amplifier includes an active amplifier in the feedback path of the modulator. In one embodiment, the class D amplifier includes a fully differential amplifier as an input buffer, in which a supply-independent reference voltage is used as the common mode voltage of the output of the fully differential amplifier. In one embodiment, the class D amplifier includes a pulse width modulation circuit that includes rail-to-rail comparators.