Class-D amplifier system

An audio amplifier system comprising:

• an Nth order loop filter, where N>1, configured to integrate an error signal functionally related to a difference between an input signal representing an audio signal and a feedback signal corresponding to an output signal of the audio amplifier system, the loop filter providing at least one corresponding integrated output signal;
• a comparator that provides a guantized outout signal based on the at least one corresponding integrated output signal;
• an output staae connected between a first voltage rail and a second voltage rail, at least one of the first voltage rail and the second voltage rail being an unregulated voltage, the output stage modulating the output signal between the first voltage rail and the second voltage rail based on the quantized output signal, wherein the loop filter further comprises:
• a first integrator that integrates the error signal to provide a corresponding first integrated output signal at an output of the first integrator;
• and
• a second integrator provides a corresponding second integrated output signal that defines a corresponding second integrated output signal, the comparator providing the quantized output signal based on a comparison of the corresponding first integrated output signal and the corresponding second integrated output signal.

An audio amplifier system comprising:

• means for integrating an error signal functionally related to a difference between an input audio signal and a feedback signal corresponding to an output signal at an output of the audio amplifier system, and for providing an first signal at first output and a second integrated output signal at a second output of the means for integrating;
• means for comparing the first signal and the second integrated signal to provide a quantized output signal;
• and
• means for modulating the output signal between a first unregulated voltage and a second voltage based on the quantized output signal.