The present invention relates to a class-D amplifier circuit appropriate for a power amplifier of an audio apparatus and the like.
Technologies for preventing clipping of an output signal of a class-D amplifier circuit have been proposed. For example, JP-A-2010-187399 discloses a class-D amplifier circuit including a clipping prevention controller for controlling a switch interposed between input ends which receive two input signals having a normal phase and a reverse phase. The clipping prevention controller attenuates the input signals by controlling the switch such that the switch is turned on periodically and intermittently when clipping occurs.
However, in JP-A-2010-187399, even if the levels of the input signals decrease during an operation of the clipping prevention controller, attenuation of the input signals may not stop immediately such that the input signals having levels in an appropriate range in which clipping on output signals does not occur are attenuated. Moreover, even if the sound volume of the input signals is adjusted during the operation of the clipping prevention controller, actually, the sound volume of the output signals rarely changes.
USPTO Backgrounds
USPTO Backgrounds