| 摘要 |
PURPOSE:To improve the performance of the titled circuit, by compensating for temperature of the optimum amplification factor of a photodetector and the optimum discrimination level of a discrimination circuit. CONSTITUTION:An optical input signal inputted from an input terminal Vin is converted into an electric signal by an avalanche photodiode 1, the electric signal is amplified by an amplifier 2 and the amplified signal is reproduced by a DC reproducing circuit 3. The reproduced signal is discriminated by a discrimination circuit 4 in accordance with a gain controlling voltage and discrimination level voltage generating circuit 7 and an output is generated from an output terminal Vout. On the other hand, the peak-to-peak value of the output signal of the DC reproducing circuit 3 is detected by a peak-to-peak value detecting circuit 6 and gain controlling voltage is applied from the circuit 7 to a bias voltage controlling circuit 5 so as to keep the peak-to-peak value constant, and the circuit 5 determines the bias voltage of the avalanche photodiode 1. Thus temperature compensation is attained by the circuit 7. |
