| 摘要 |
PROBLEM TO BE SOLVED: To provide a class D amplifier for performing an appropriate amplifying operation for each input signal with different sampling frequency without causing an increase in circuital size. SOLUTION: The class D amplifier includes a PWM signal generating circuit for converting from an input sinal S1 of 8-64 kHz in frequency to a PWM signal of 16-128 kHz, a driver circuit for enhancing drive performance of the PWM signal S2, and an LPF for smoothing the PWM signal with a time constant corresponding to 64 kHz. If the PWM signal S2 is 128 kHz, generation and output are carried out by the PWM signal generating circuit while performing approaching operation and retracting operation of the pulse for each Tb. If it is 64 kHz, generation and output are carried out by the PWM signal generating circuit while treating the pulse approaching and retracting operations as uniform for each Tb. If it is 32 kHz or 16 kHz, the output is carried out not only from basic pulse but just after inserting an additional pulse, which makes the Tb into two or four divisions in this constitution. COPYRIGHT: (C)2007,JPO&INPIT
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