Patent ID: 9564862
Date: 2017-02-07
CPC Classifications: H02M,H03F

Claim:
1. A class D audio amplifier comprising: a first output driver comprising a first output node connectable to a loudspeaker load to supply a load signal thereto; said first output driver comprising an upper leg having one or more semiconductor switches coupled between a first supply voltage and the first output node and a lower leg having one or more semiconductor switches coupled between the first output node and a second supply voltage, wherein each of the semiconductor switches comprises a switch control terminal adapted to control a state of the semiconductor switch to selectively place the semiconductor switch in its on-state or off-state; a pulse width modulator for receipt of a filtered audio signal and generation of a first set of pulse width modulated control signals at an adjustable modulation frequency for respective switch control terminals of the first output driver; a feedback loop comprising an adjustable loop filter and a summing node coupled to an audio input signal and a feedback signal derived from the load signal, the feedback loop being configured to couple the feedback signal to the summing node; and a controller configured to control frequency response characteristics of the adjustable loop filter based on a frequency setting of the adjustable modulation frequency of the first set of pulse width modulated control signals.