| 摘要 |
PURPOSE:To make an output amplitude of a light receiving and amplifier circuit constant and a frequency band constant by providing a control circuit controlling a variable load resistor and a variable frequency characteristic equalizer for an optoelectric converting element. CONSTITUTION:The frequency band depending on the optoelectric converting element 1 and the receiving amplifier 3 is inversely proportional to a resistance value R of the variable load resistor 2. Thus, the frequency band of the variable frequency characteristic equalizer 4 is controlled in proportion to the resistance value R, then the frequency band is made constant. Then the change in the input optical power of the converting element 1 is detected by a control circuit 5 and the value of the resistor 2 and the parameter of the equalizer 4 are controlled depending on the result of detection. thus, the output amplitude of the light receiving and amplifier circuit is made constant and the frequency band is made constant. |
