| 摘要 |
PURPOSE:To obtain the signal output of a high output, which is excellent in its frequency selecting characteristic, by connecting a vibrator in parallel to the load resistance of a photodiode of a photodetector of an optical signal, forming a resonance circuit and making a modulating signal frequency of light coincide with the resonance frequency of the resonance circuit. CONSTITUTION:A crystal resonator 7 is connected in parallel to a load resistance 3. An equivalent circuit when a photodiode 1 side is seen from the input terminal of an amplifier 2 forms a resonance circuit and when the modulation frequency of an optical signal coincides with the resonance frequency of the resonance circuit, the resonance impedance of the resonance circuit becomes extremely high, therefore, the input level of an amplifier 2 becomes higher than an input level when the crystal resonator 7 is not connected. Accordingly, the level outputted to the output terminal 6 of the amplifier also becomes high, and the sensitivity of this optical signal receiver is improved. |
