| 摘要 |
PURPOSE:To obtain digital information with correct input signal level even if the DC voltage of the input signal is fluctuated by changing a reference voltage based on an error voltage between a voltage division voltage of a reference voltage used for an analog digital conversion and a DC voltage of the input signal. CONSTITUTION:A reference signal of a prescribed signal level is superimposed on an input signal SV in a prescribed timing. An error amplifier circuit 14 is provided, which detects an error voltage between a prescribed reference division voltage VRB3 and the DC voltage of the reference signal, and the reference voltage VRB is changed based on an output signal VRB of the error amplifier circuit 14 to convert the signal level of the input signal SV into the digital information DS. Thus, even when the input signal SV whose DC voltage is fluctuated with respect to the signal level, prescribed comparator circuits COM1-COM256 are always turned on and the digital information with a correct value with respect to the signal level of the input signal SV is obtained.
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