| 摘要 |
PURPOSE: To reduce an error of a threshold and to prevent the duty factor of a signal from being deteriorated in a photodetector to be used for receiving a burst-like optical signal. CONSTITUTION: The photodetector is provided with an amplification means 33 for differentially amplifying specific pattern-added data sent from a photoelectric conversion means 37 around an impressed threshold and outputting the differentially amplified result, a maximum amplitude value detecting means for detecting the maximum amplitude value of the specific pattern-added data and a voltage dividing means 35 for dividing the voltage of the inputted maximum amplitude value and reference voltage and generating a threhold. The photodetector is also provided with a difference detecting means 1 for detecting and sending a difference of a low frequency component in the differential output outputted from the means 33 and a storing means 2 for storing the inputted difference as it is when the difference is in a specific pattern area or storing the difference in the specific pattern area in the case of a data area and sending the stored contents to the means 35 as reference voltage and the means 1 is constituted so as to control the reference voltage so that the difference of the low frequency component is minimized. |
