Audio amplifier and method of operating the same

A method of operating an audio amplifier, the method comprising:

• receiving an audio signal through an input terminal of a loop filter of the audio amplifier;
• generating a pulse-width modulation (PWM) signal corresponding to the audio signal;
• generating an output signal to be output to a speaker, based on the PWM signal;
• feeding back the output signal to the loop filter;
• and
• compensating for a fluctuation in a common mode voltage of the fed-back output signal,
• wherein
• compensating for the fluctuation comprises:
• generating a compensation voltage for each of a plurality of levels of the common mode voltage;
• and
• providing the generated compensation voltage to the loop filter.

A class D audio amplifier with BD modulation, the class D audio amplifier comprising:

• a loop filter;
• a pulse-width modulation (PWM) signal generator;
• a gate driver;
• a power driver;
• a feedback circuit;
• and
• a common mode compensation circuit,
• wherein
• the common mode compensation circuit comprises a control node connected to a first input terminal and a second input terminal of the loop filter, and
• the common mode compensation circuit is configured to:
• apply a ground voltage to the control node when both a first output signal and a second output signal of the class D audio amplifier are at a high level;
• apply a driving voltage to the control node when both the first output signal and the second output signal are at a low level;
• and
• apply a mean voltage of the driving voltage and the ground voltage to the control node when one of the first and second output signals is at a high level and the other one of the first and second output signals is at a low level.