| 摘要 |
PROBLEM TO BE SOLVED: To provide a class-D amplifier adopting the feedback system wherein the distortion factor is enhanced by reducing the effect of a remaining carrier of a PWM modulation signal. SOLUTION: The class-D amplifier 20 includes: an operational amplifier for amplifying an audio signal Vin; a pulse width modulation circuit 5; an output stage switching transistor 9; a driver circuit 7 for receiving a pulse width modulation output signal VPWM to switch the output stage switching transistor 9; an output low pass filter 41; and a feedback loop 8 for feeding back an output signal Vout to an input of the operational amplifier 1, and the feedback loop 8 is configured such that a residual carrier reduction circuit 15 comprising: a sampling circuit 11 for sampling the output signal Vout with a clock frequency the same as that of the pulse width modulation circuit 5; and a low pass filter 14 for eliminating high frequency components of the output signal Vout is inserted to the feedback loop 8. COPYRIGHT: (C)2007,JPO&INPIT
|
