| 摘要 |
PROBLEM TO BE SOLVED: To facilitate gain setting for taking an average output sound pressure level by a large amount in the average input signal level part of a digital power amplifier. SOLUTION: In the digital power amplifier, with which an audio frequency band signal S3 is inputted to aΔΣmodulator 23 and this signal S3 is made into a power switch control signal S11, such as a pulse density modulated signal or a PWM signal via the relevantΔΣmodulator, so that a power switching signal 13 provided on the basis of this control signal S11 can be made into signal capable of being supplied to a load 7; the operation of thisΔΣmodulator 23 is stabilized by controlling the gain of a signal gain controller 2, provided on the prestage side of thisΔΣmodulator 23 by a detection means 21 for detecting the peak signal strength of this inputted digital signal; and the upper limit of the average signal level of this signal S3 capable of being inputted to theΔΣmodulator 23 is increased, so that the reproducing output of this average signal level is improved.
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