Patent ID: 7649410

Claim:
A switching amplifier comprising: an ultrasonic signal generator that generates an ultrasonic signal having an ultrasonic frequency; a modifier that receives an audio signal and the ultrasonic signal, and that modifies the audio signal in dependence on the ultrasonic signal to thereby generate a modified audio signal; a modulator that receives the modified audio signal and that generates a pulse width modulated switching waveform in dependence on the modified audio signal and a carrier signal having a switching frequency Fs that is different than the ultrasonic frequency; and power switches that generate an output in dependence on the pulse width modulated switching waveform; wherein the modification of the audio signal, in dependence on the ultrasonic signal, results in the generated pulse width modulated switching waveform preventing the power switches from switching simultaneously or nearly simultaneously at low levels of the audio signal, thereby reducing distortion at low levels of the audio signal that would otherwise occur if the power switches switched simultaneously or nearly simultaneously.