Patent ID: 8311243

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 substantially symmetric about a reference potential, forming a bi-polar power supply input; and a charge pump power supply for providing a bi-polar power supply voltage across said pair of power supply rail connections of said power amplifier, wherein said charge pump power supply has a select input for selecting an operating mode of said power supply, wherein in a first operating mode, said bi-polar power supply voltage is equal to a first voltage, and wherein in a second operating mode said bi-polar power supply voltage is substantially equal to a rational fraction of said first voltage, wherein in both of the first operating mode and the second operating mode, the bipolar power supply voltage is substantially symmetric about the reference potential, and wherein in the second operating mode a first flyback capacitor and a second flyback capacitor are coupled in series during a first charging phase of the charge pump power supply, and separately provide charge to corresponding ones of the pair of power supply rail connections during a second discharging phase of the charge pump power supply.