Patent ID: 7970291

Claim:
An optical-receiving apparatus comprising; an avalanche photodiode converting input light to an electric signal; a bias circuit generating a bias voltage applied to the avalanche photodiode based on a control signal; a temperature monitor circuit monitoring an ambient temperature of the avalanche photodiode; a current monitor circuit monitoring a current flowing through the avalanche photodiode; an amplification circuit amplifying the current flowing through the avalanche photodiode at a predetermined magnification; a selection circuit selectively transmitting a signal so that when a current value monitored by the current monitor circuit is larger than a predetermined value, the signal of the current value is transmitted, and when the current value is smaller than or equal to the predetermined value, the signal of a current value amplified by the amplification circuit is transmitted; and an operating circuit generating an attenuated signal so that when the current value is smaller than or equal to the predetermined value the operation circuit attenuates the signal transmitted from the selection circuit at the predetermined magnification, and controlling the bias circuit so that a multiplication factor corresponding to the ambient temperature monitored by the temperature monitor circuit becomes equal to a predetermined multiplication factor.