Patent ID: 8472644

Claim:
A high efficiency audio amplifier, comprising: an input end for receiving an input audio signal; an output end for outputting an output audio signal; a signal generator, comprising: a determination circuit coupled to the input end for determining a frequency of an oscillating signal according to the distribution of the input audio signal and a reference voltage and generating a control signal accordingly; and a waveform generator coupled to the determination circuit for generating the oscillating signal according to the control signal; a waveform transformer coupled to the input end and the signal generator for comparing the input audio signal with the oscillating signal to generate a pulse width modulation (PWM) signal; a pre-drive circuit coupled to the waveform transformer for generating a pre-drive signal according to the PWM signal; an output stage coupled to the pre-drive circuit for generating an output signal; and a filter coupled to the output stage for filtering the output signal to generate the output audio signal to the output end; wherein the determination circuit increases the frequency of the oscillating signal and generates the control signal accordingly when the input audio signal is greater than the reference voltage.