| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a pop noise preventing circuit capable of preventing pop noise at start and stop. <P>SOLUTION: In an amplifier wherein a PWM signal subjected to PWM modulation according to an input signal is smoothed by a low pass filter ( L11 and C12) via a coupling capacitor C11 and the smoothed signal is applied to a speaker SP, an analog switch circuit 30 receives a clock having the same amplitude as that of the PWM signal at application of power, and an internal resistance of the analog switch circuit 30 is gradually decreased to charge up in advance the coupling capacitor C11 by using the clock. <P>COPYRIGHT: (C)2004,JPO</p> |
