| 摘要 |
PROBLEM TO BE SOLVED: To improve the carrier to noise ratio (C/N) by making an amplitude frequency characteristic flat from a low frequency to a high frequency and increasing the reception sensitivity. SOLUTION: A coil 3 (5) is provided to an anode (cathode) of a PIN photo diode module 4 respectively to form a resonance circuit with a capacitor of the PIN photo diode module 4 or the like so as to compensate deterioration in the amplitude frequency characteristic of an optical current due to the capacitance at a high frequency region. Furthermore, the reception sensitivity is improved by utilizing a current multiplier effect of a transformer 6 through the amplification of an optical current with an amplifier via the transformer 6. |
