| 摘要 |
PURPOSE:To detect whether an optical fiber from a transmission side is connected or not by load resistance which converts the output current of a photodiode into a voltage and FET which transmits the voltage to a next stage with a low impedance. CONSTITUTION:The input resistor 14 of the next stage is connected with external terminals 17 and 18 at every channel so as to be an input to an amplifier circuit. The output current of the photodiode 11 is converted into the voltage by integrated load resistor 12 and outputted to the terminals 17 and 18 as the low impedance signal by FET 13. That is, the anode terminal of the part 11 with the high impedance is processed inside an integrated array element and receives hardly the disturbance. Furthermore, the impedance is high in FET 13 so that the load resistance of the photodiode 11 can be made high. Thus, the output signal of the photodiode 11 is efficiently transmitted to the next stage. Then, the voltage dropping in a resistor 20 is detected and whether the optical fiber from the transmission side is connected with the photodiode 11 or not is detected, as well. |
