| 摘要 |
<P>PROBLEM TO BE SOLVED: To prevent a photodiode from being destroyed when an excessive optical signal is inputted, and to prevent a receiving signal of excessive signal level from being inputted to the subsequent amplifier. <P>SOLUTION: Between a power source Vcc and a ground, a current limiter circuit 10, a coil L1, a PD 12 and a resistor R1 are connected, in series. An optical signal is being inputted to the PD 12 by an optical fiber 11 and an inverse current, corresponding to the intensity of the inputted optical signal flows in the PD 12. Even if an excessive optical signal is inputted to the PD 12, reverse current flowing to the PD 12 is limited to a current value which is to be determined by the current limiter circuit 10. <P>COPYRIGHT: (C)2009,JPO&INPIT |
