Patent ID: 7629840

Claim:
A switching amplifier comprising: a power stage having an input terminal and an output terminal; a low pass filter having an input terminal coupled to the output terminal of the power stage, and an output terminal for providing a filtered pulse width modulated signal; a combining circuit having a first input terminal coupled to the output terminal of the power stage, a second input terminal coupled to the output terminal of the low pass filter, and an output terminal, the combining circuit comprising: a first capacitive element having a first plate electrode coupled to the output terminal of the power stage, and a second plate electrode; a first resistive element having a first terminal coupled to the second plate electrode of the first capacitive element, and a second terminal coupled to the output terminal of the low pass filter; a second resistive element having a first terminal coupled to the second plate electrode of the first capacitive element, and a second terminal coupled to the output terminal of the combining circuit; and a third resistive element having a first terminal coupled to the second terminal of the second resistive element, and a second terminal coupled to a power supply voltage terminal; and a digital feedback correction circuit having a first input terminal for receiving a reference pulse width modulated signal, a second input terminal coupled to the output terminal of the combining circuit, and an output terminal coupled to the input terminal of the power stage.