| 摘要 |
PURPOSE:To receive stably a burst light signal by amplifying the difference between outputs of a preamplifier which are passed through a delay circuit and not passed through the delay circuit. CONSTITUTION:The signal after the opto-electric conversion of a photodetecting element 1 is amplified by the preamplifier 12. The output of the preamplifier 12 is divided into two; one is inputted to the delay circuit 13 having delay time T equal to the width of a pulse with a maximum transmission speed and its output is supplied to the negative input of a differential amplifier 14. The other output of the preamplifier 12 is inputted to the positive input of the differential amplifier 14 as it is and its output is inputted to a Schmitt trigger circuit 16 through a capacitor 15. Input/output characteristics of the circuit 16 are as shown in a figure. Therefore, the input DC voltage of the circuit 16 is set to V0 almost in the middle of voltages V1 and V2 through a variable resistance 17 and a resistance 18, thereby obtaining a correct output waveform. |
