| 摘要 |
PROBLEM TO BE SOLVED: To receive the data of an optical signal correctly even if the intensity of an optical signal received by a light-receiving element is weak.SOLUTION: In the downstream of a filter receiving a waveform signal generated based on the output from a light-receiving element for receiving an optical signal and converting into an electric signal, there is a voltage generation circuit which forms a reference voltage for defining the bias voltage of a filter output waveform, and a variable gain amplifier for amplifying the filter output waveform output from the filter. A control circuit for controlling the reference voltage and the gain of the variable gain amplifier based on the output therefrom boosts the bias voltage of a filter output waveform depending on the undesired dullness of the output waveform of the variable gain amplifier, and controls the gain thereof so as to decrease than present. |
