Class-D amplifier

A class-D amplifier, comprising:

• a first resistor;
• a second resistor;
• a loop filter coupled to the first resistor and the second resistor and configured to receive a first feedback signal and a second feedback signal, and to receive a first input signal and a second input signal respectively through the first resistor and the second resistor, wherein the loop filter filters the first input signal, the second input signal, the first feedback signal, and the second feedback signal to generate a first filtered signal and a second filtered signal;
• a triangle wave generator configured to generate a triangle wave according to a first reference voltage and a second reference voltage;
• a first comparator coupled to the loop filter and the triangle wave generator and configured to compare the first filtered signal with the triangle wave to generate a first pulse width modulation (PWM) signal;
• a second comparator coupled to the loop filter and the triangle wave generator and configured to compare the second filtered signal with the triangle wave to generate a second PWM signal;
• a first driver circuit coupled to the first comparator and configured to generate a first output signal according to the first PWM signal;
• a second driver circuit coupled to the second comparator and configured to generate a second output signal according to the second PWM signal;
• a third resistor coupled between the first driver circuit and the loop filter;
• a fourth resistor coupled between the second driver circuit and the loop filter;
• and
• a common-mode voltage generation circuit coupled to the loop filter and configured to generate a common-mode voltage according to a control signal;
• wherein the loop filter comprises an integrator, the integrator comprises an operational amplifier, and the common-mode voltage is the common-mode voltage of the operational amplifier.