Patent ID: 8896376
Filing Date: 2014-11-25
Classification: H03F

Abstract:
1. A digital amplifier that receives a digital signal and drives a speaker directly with the digital signal, the digital amplifier comprising: a digital modulation circuit that performs digital pulse width modulation on digital audio data; a first analog audio output section that performs low-pass filtering of a pulse voltage that is output from the digital modulation circuit and outputs an analog audio voltage; a triangular wave generation circuit that generates an amplitude-modulated triangular wave based on a value of a modulation width of the digital pulse width modulation; a drive circuit that amplifies an output voltage from the triangular wave generation circuit; a second analog audio output section that performs low-pass filtering of a signal power-amplified by the drive circuit and outputs audio band analog power; and an error amplifier that computes and amplifies a voltage difference between a voltage of the first analog audio output section and a voltage of the second analog audio output section, wherein the triangular wave generation circuit adds an error from the error amplifier to a signal corresponding to the value of the modulation width of the digital pulse width modulation and regenerates a digital pulse width modulation waveform.