Patent ID: 7714646

Claim:
An audio power amplifier, comprising: a pre-amplifier for amplifying an audio signal, wherein the pre-amplifier comprises: an operational amplifier having a first input terminal receiving a reference voltage; and an input signal controller connected between an output terminal and a second input terminal of the operational amplifier, wherein the input signal controller receives a voltage signal whose voltage level gradually decreases when the audio power amplifier is powered on; an error amplifier, generating an error signal by comparing the amplified audio signal and a feedback signal; a comparator generating a PWM signal by comparing a reference signal and the amplified audio signal; a bridge circuit, having switches controlled according to the PWM signal such that a driving current alternately flows to and from a load; and a feedback circuit generating the feedback signal indicating a condition of the load, wherein a gain of the pre-amplifier gradually increases when the audio power amplifier is powered on.