Patent ID: 8126164

Claim:
A digital audio circuit comprising: a power amplifier that generates an output drive signal responsive to a digital audio signal; a digital gain stage that adjusts an amplitude of the digital audio signal prior to application to the power amplifier; a variable power supply that biases the power amplifier to a voltage corresponding to a volume control signal; and digital gain control circuitry that applies a control signal to the digital gain stage to temporarily reduce the amplitude of the digital audio signal responsive to a reduction of a desired volume indicated by the volume control signal, wherein the digital gain control circuitry includes: add/subtract circuitry having an input coupled to receive a signal corresponding to an output voltage from the variable power supply and an input coupled to receive the volume control signal; and comparison circuitry that generates the control signal to the digital gain stage responsive to the output voltage from the variable power supply at a gain level exceeding that indicated by the volume control signal.