Class-d amplifier with nested feedback loops

An audio amplifier that generates an amplified output signal, comprising:

• first and second summing nodes;
• a switch node;
• a switching amplifier coupled between the switch node and the first summing node;
• a filter coupled to the switch node;
• a global feedback loop coupled to the filter;
• and
• a nested amplifier portion comprising a first feedback loop nested within a second feedback loop, wherein:
• the first feedback loop comprises:
• a first loop feedback module that provides a first feedback signal from the switch node to the first summing node;
• and
• the second feedback loop provides a second feedback signal from the switch node to the second summing node, the second feedback loop comprises:
• a second loop feedback module coupled between the switch node and the second summing node;
• and
• a second loop integrator module coupled to the second summing node.

An audio amplifier that generates an amplified output signal, comprising:

• first, second, and third summing nodes;
• a switch node;
• a switching amplifier coupled between the switch node and the first summing node;
• and
• a nested amplifier portion comprising a first feedback loop nested within a second feedback loop nested within a third feedback loop, wherein:
• the first feedback loop comprises a first loop feedback module that provides a first feedback signal from the switch node to the first summing node;
• the second feedback loop comprises a second loop feedback module that provides a second feedback signal from the switch node to the second summing node;
• and
• the third feedback loop comprises a third loop feedback module that provides a third feedback signal from the switch node to the third summing node, the third feedback loop further comprising:
• a third loop integrator module coupled to the second summing node;
• a third loop compensator module coupled to the second loop integrator module;
• and
• a third loop forward compensator module coupled between the second loop compensator module and the second summing node.

An audio amplifier, comprising:

• first, second, and third summing nodes;
• a switch node;
• a switching amplifier coupled between the switch node and the first summing node;
• and
• a nested amplifier portion configured to generate an amplified signal portion driven on the first summing node, the nested amplifier portion comprising a first feedback loop nested within a second feedback loop nested within a third feedback loop, wherein the third feedback loop provides a feedback signal portion from the switch node to the third summing node, the third feedback loop comprising:
• a third loop feedback module coupled between the switch node and the third summing node;
• a third loop integrator module coupled to the third summing node;
• a third loop compensator module coupled to the third loop integrator module and a compensator node, with the second loop integrator module between the second loop compensator module and the compensator node;
• and
• a third loop forward compensator module coupled between the third loop compensator module and the second summing node.