Patent ID: 8362833
Filing Date: 2013-01-29
Classification: H03F

Abstract:
1. An amplifier circuitry comprising a class-D amplifier for amplifying an audio input signal, the amplifier circuitry comprising: sigma-delta modulation logic arranged to receive the audio input signal and to generate a modulated signal that is representative of the audio input signal; an output stage arranged to generate an output signal based on the modulated signal; a finite impulse response, FIR, digital filter, operably coupled between the sigma-delta modulation logic and the output stage, and having at least one zero in its transfer function arranged to substantially pass signal components within the modulated signal occurring at frequencies less than the at least one zero and to attenuate signal components within the modulated signal at frequencies greater than the at least one zero; at least one feedback loop arranged to provide feedback signal to the sigma-delta modulation logic from the output signal; and at least one further feedback loop arranged to provide feedback to the sigma-delta modulation logic from the modulated signal generated thereby; the at least one feedback loop arranged to provide feedback from the sigma-delta modulation logic comprises power supply representation logic arranged to introduce a representation of power supply noise into the at least one feedback loop.