| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical receiving circuit capable of preventing the damage to a photodetector though the photodetector inputs excessive optical signals. SOLUTION: Current flowing through the photodetector 3 is detected by a detection means, and the current is error-amplified by an error amplifier 8. When the current comes to have a prescribed value, bias voltage applied to the photodetector is dropped to restrict photodetecting current to be equal to or lower than a maximum allowable current. As a result, the photodetector 3 is prevented from being deteriorated or destroyed though the photodetector 3 inputs the excessive optical signals. |
