| 摘要 |
PROBLEM TO BE SOLVED: To reduce deterioration in the efficiency of a switching amplifier due to the formation of a PWM signal by level comparison between an analog input signal and a triangular wave signal when the power amplification of the PWM signal is performed by a switching amplification section to supply an amplification output signal to a load. SOLUTION: This circuit is provided with an NPN transistor 16 for generating a power amplification output signal PPA corresponding to a portion acquired under a condition that the level of an input signal in the PWM signal is not less than the level of the triangular signal; a PNP transistor 17 for generating a power amplification output signal PPB corresponding to a portion acquired under a condition that the level of an input signal in the PWM signal is lower than the level of the triangular signal; a differential circuit 20 for generating a differential output signal selectively indicative of a level increase of the input signal and a level decrease thereof; and output suppressors 14, 15 and 21 each suppressing the generation of the power amplification output signal PPB when the differential output signal is indicative of the level increase portion of the input signal, and suppressing the generation of the power amplification output signal PPA when the differential output signal is indicative of the level decrease portion of the input signal. COPYRIGHT: (C)2005,JPO&NCIPI
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