| 摘要 |
PROBLEM TO BE SOLVED: To provide a class D amplifier circuit the output sound signal of which is unchnaged when a power supply voltage is fluctuated. SOLUTION: A division voltage of a power supply voltage V<SB>DD</SB>is used for a power supply voltage of a triangle wave generating circuit 30 so that the amplitude of a triangle wave S2 of a PWM carrier signal is changed in proportion to a variation in the power supply voltage V<SB>DD</SB>supplied to a switching amplifier 6. For example, even when the power supply voltage V<SB>DD</SB>of the switching amplifier 6 is increased resulting in increasing the amplitude of a PWM amplifier signal S4, the increase of the amplitude is cancelled by the pulse width of the PWM amplifier signal S4 that is narrowed and the level (amplitude) of an output sound signal S5 is unchanged. COPYRIGHT: (C)2005,JPO&NCIPI
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