US Patent 7786795 Class-D amplifier circuit

A class-D amplifier circuit of one aspect includes a gain controller, a pulse-width modulator, an output driver, and a drive controller. The gain controller selectively amplifies an analog input signal according to a level control signal, and outputs a corresponding gain-adjusted analog input signal. The pulse-width modulator converts the gain-adjusted analog input signal into a pulse signal. The output driver includes a plurality of output driver circuits which generate an amplified pulse signal corresponding to the pulse signal output by the pulse-width modulator. The drive controller selectively disables a subset of the plurality of output driver circuits according to the level control signal.