Patent ID: 9112467
Filing Date: 2015-08-18
Classification: H02M,H03F,H03G

Abstract:
1. An audio amplifier circuit for providing an output signal to an audio transducer, the audio amplifier circuit comprising: a power amplifier having an audio input for receiving an audio input signal, an audio output for providing the output signal, and a pair of power supply rail connections; a power supply for providing a power supply voltage across the pair of power supply rail connections of the power amplifier, wherein the power supply has a select input for selecting an operating mode of the power supply, wherein in a first operating mode, the power supply voltage is equal to a first voltage, and wherein in a second operating mode the power supply voltage is substantially equal to a rational fraction of the first voltage, whereby power consumption of the power amplifier is reduced when a magnitude of the audio input signal is reduced; a control circuit for controlling the select input of the power supply in conformity with an indication of the magnitude, so that the control circuit selects the first operating mode when the indication of magnitude indicates that clipping may occur in the output signal; and a gain control circuit for controlling a magnitude of the audio input signal in conformity with the indication of the magnitude for a predetermined period after the control circuit selects the first operating mode of the power supply.