Patent ID: 7538607

Claim:
A class D amplifier comprising: a PWM circuit for receiving input data and converting the input data to a PWM signal; a low pass filter for passing low frequency components of the PWM signal; a digital to analog converter for converting the input data to an analog signal; a filter for only passing wanted frequency components of the analog signal from the digital to analog converter; a difference detector for detecting a difference between a signal output from the low pass filter and a signal output from the filter; a conversion unit for converting the detected difference to digital data; and a feedback unit for feedbacking the converted digital data to an input of the PWM circuit, wherein: the PWM circuit outputs a quantization noise; and the feedback unit includes a combining circuit for combining the quantization noise of the PWM circuit and an output of the conversion unit, and feeds back an output of the combining circuit to the input of the PWM circuit.