| 摘要 |
PROBLEM TO BE SOLVED: To provide a muting circuit that can prevent production of a switching noise even when muting is applied to an audio signal encoded into a 1-bit digital signal in an optional timing. SOLUTION: AΔΣconverter 1 of the muting circuit 21 appliesΔΣconversion processing to an input signal (a) compatible with a 1-bit signal (d) and gives the 1-bit signal (d) to a mute section 4. When muting is instructed, a zero cross detector 2 detects a zero cross timing of the input signal (a) received by theΔΣconverter 1 to provide an output of a detection signal (b), which is given to a delay device 3, the delay device 3 delays a control signal (c) by a delay time equal to a conversion time of theΔΣconverter 1 from the input timing of the input signal (a) in the zero cross timing to theΔΣconverter 1 and gives the delayed control signal to the mute section 4 which starts outputting a 1-bit neutral signal (e).
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