AUDIO AMPLIFIER

摘要

Noise during muting can be suppressed in an audio amplifier having a D-class power amplifier. The audio amplifier includes a sampling rate converter circuit (23) for sampling-rate converting a digital audio signal S11 into a digital audio signal S23 and a DeltaSigma modulation circuit (14) for re-quantizing the digital audio signal S23 into a digital audio signal S14 having a smaller number of bits. The audio amplifier further includes a PWM modulation circuit (15) for converting the digital audio signal S14 into a PWM signal S15 and a D-class power amplifier (16) supplied with this PWM signal S15. Moreover, there are provided a dither signal formation circuit (18) for superimposing a dither signal SDI on the digital audio signal S23 and a circuit (19) for forming a muting signal SDET. During muting, the muting signal SDET stops the input side of the sampling rate converter circuit (23).