| 摘要 |
PURPOSE:To receive desired signals especially with high S/N and low distortion easily, by providing a tuning circuit for a load of a photodiode in a demodulation section of modulated optical signals, in a receiver for optical communication. CONSTITUTION:A tuning circuit 10 consisting of a coil 11 and a capacitor 12 is constituted as a load of a photodiode 1. The impedance of the circuit 10 is high at a tuning frequency and low at frequencies separated from the tuning frequency. In matching the tuning frequency of the tuning circuit 10 to the frequency of a desired television channel, the level of demoduated signals of the frequency of a desired television channel appeared at an input terminal P is higher, and the level of the demodulated signals of the frequency of the television channel not desired is low, the S/N at the input terminal P is largely improved, and a high frequency amplifier with low noise and high gain is not especially required for a high frequency amplifier 4. |
