SWITCHING AMPLIFIER USINGΔΣMODULATION

摘要

PROBLEM TO BE SOLVED: To suppress distortion caused by a large amplitude by means of L and C components of a low-pass filter. SOLUTION: This amplifier 21 is configured such that a sound signal from an analog signal source 22 isΔΣ-modulated in aΔΣmodulation loop, a constant voltage switch 26 switches a constant voltage in response to the modulation signal and a low-pass filter 27 converts its switching output into an analog signal and provides an output. In this case, a 2nd feedback loop 35 where an output of the low-pass filter 27 is fed back is formed to suppress occurrence of distortion in addition to a 1st feedback loop 31 provided in theΔΣmodulation loop 23 in order to a quantization error by a quantizer 25 and to compensate a switching noise by a constant voltage switch 26.