| 摘要 |
PURPOSE:To prevent the degradation of reception sensitivity over a wider temperature range in comparison with conventional operation by providing a temperature sensor, a storing circuit and a subtracting amplifier and correcting the temperature change part of a noise component in a photo-detecting element with using the storing circuit. CONSTITUTION:An optical signal (a) is inputted to a photo-detecting element 1 and optical-electric conversion is executed. Then, the signal is outputted and the temperature of the element 1 is detected by a temperature sensor 2, which is closed to the element 1, and converted to a voltage. After that, an output signal (b) is inputted to a storing circuit 3. The data for correction of an influence, which is given to an optical automatic gain control(AGC) circuit by the temperature change part of the noise component in the element 1, are stored to the circuit 3 in advance and correcting data (d) are outputted in correspondence to input temperature information. Next, the data to correct the influence, which is given to the AGC circuit by the temperature change part of the noise component in the element 1, are subtracted from the output component of the element 1, amplified and outputted by a subtracting amplifier 4. Thus, since the temperature change part of the noise component in the element 1 can be ignored, the degradation of the reception sensitivity can be prevented over the wide range. |
