Class-D amplifier able to reduce power noise

A Class-D amplifier, comprising:

• a loop filter circuit configured to generate a first signal according to a first input signal and a first output signal, generate a second signal according to a second input signal and a second output signal, and adjust a common-mode level of each of the first signal and the second signal according to a first common-mode signal;
• a comparator circuitry configured to compare the first signal with a ramp signal to generate a first pulse signal, and compare the second signal with the ramp signal to generate a second pulse signal, wherein a common-mode level of the ramp signal is set based on a second common-mode signal;
• an output circuitry configured to be powered by a power supply voltage to generate the first output signal according to the first pulse signal and to generate the second output signal according to the second pulse signal;
• and
• a common-mode control circuitry configured to perform an AC-coupling operation on the power supply voltage to generate a first noise signal and generate a first one of the first common-mode signal and the second common-mode signal according to the first noise signal and a second one of the first common-mode signal and the second common-mode signal,
• wherein the common-mode control circuitry comprises:
• a high-pass filter circuit configured to perform the AC-coupling operation on the power supply voltage to generate the first noise signal;
• a common-mode voltage generator circuit configured to provide the second one of the first common-mode signal and the second common-mode signal;
• a first amplifier circuit configured to adjust the first noise signal based on a predetermined gain to generate a second noise signal;
• and
• an adder circuit configured to add the second noise signal and the second one of the first common-mode signal and the second common-mode signal, in order to generate the first one of the first common-mode signal and the second common-mode signal.