| 摘要 |
<P>PROBLEM TO BE SOLVED: To prevent pop-noise from occurring when turning on/off application of a PWM signal to a class-D amplifier. Ž<P>SOLUTION: A first situation indicating that a system is in a power-on situation or in an un-mute situation, or a second situation indicating that the system is in a power-off situation or in a mute situation, is detected. When the first situation is detected, a differential PWM signal including a plurality of pulses each having a gradually increased width and the subsequent pulse train of 50% duty cycle pulses are generated and, if the output of an audio processor is in a stable situation, sent to the amplifier via a multiplexer. When the second situation is detected, the differential PWM signal including a plurality of pulses each having a gradually reduced width and the subsequent pulse train of no signal are generated and, at the same time, the generated pulses are sent to the amplifier via the multiplexer, wherein the number of pulses gradually increased/gradually reduced and each width are in a relationship satisfying equations disclosed in the present invention. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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