| 摘要 |
PROBLEM TO BE SOLVED: To provide a class D amplifier for reducing electromagnetic wave disturbance which appears relative to harmonics of a PWM carrier frequency, and wherein a level of the center frequency of the harmonics appears higher in particular as a modulation factor of a sound signal is lower. SOLUTION: A digital sound signal is given to a sound signal input terminal 1, a delta sigma modulation section 2 applies delta sigma modulation to the signal and thereafter the modulated signal is given to a PWM signal generating section 3. A sound out-band signal is given to the PWM signal generating section 3 from a modulation signal input terminal 7, and the PWM signal generating section 3 generates a PWM signal modulated by the sound out-band signal. The PWM signal is demodulated by a power switch 4 and a filter 5, and a sound signal is outputted from a sound signal output terminal 6. COPYRIGHT: (C)2006,JPO&NCIPI
|
