| 摘要 |
PROBLEM TO BE SOLVED: To provide a clip detecting circuit capable of detecting the occurrence of a clip in a self-exciting class D amplifier with a simple circuit configuration. SOLUTION: A clip detecting part includes: a positive pulse width measuring part 20 including a capacitor 24 to be charged when a PWM signal output from the switch circuit of the amplifier is on a high side; a positive clip detection signal generating part (a comparator) 21 for comparing the output voltage Vp of the positive pulse width measuring part 20 with a threshold voltage Vtp; a negative pulse width measuring part 30 including a capacitor 34 to be charged when the PWM signal is on a low side; and a negative clip detection signal generating part (a comparator) 31 for comparing the output voltage Vm of the negative pulse width measuring part 30 with a threshold voltage Vtm. The threshold voltages Vtp, Vtm are set in prescribed time within the range of 10 to 50 times as large as a period of a self-exciting oscillation frequency in a pulse width modulation signal when the level of an analog acoustic signal input to the amplifier is zero. COPYRIGHT: (C)2010,JPO&INPIT |
