Patent ID: 8068622

Claim:
An audio amplifier circuit for providing an output signal to an audio transducer, said audio amplifier circuit comprising: a power amplifier having an audio input for receiving an audio input signal, an audio output for providing said output signal, and a pair of power supply rail connections; a power supply for providing a power supply voltage across said pair of power supply rail connections of said power amplifier, wherein said power supply has a selectable power supply voltage level, whereby power consumption of said power amplifier is reduced when said magnitude of said audio input signal is reduced; a control circuit for controlling selectable power supply voltage level in conformity with an indication of said magnitude, so that clipping is prevented when said selectable power supply voltage level is increased and has not yet reached a full power supply voltage level; and a gain control circuit for controlling a magnitude of said audio input signal in conformity with said indication of said magnitude at least during a time period during which said selectable power supply level is increasing to said full power supply voltage level.