| 摘要 |
PROBLEM TO BE SOLVED: To increase an apparent gain and to improve a noise characteristic by connecting current amplification transformers (or resistors) to both ends of a PIN photodiode, which receives a light signal and making the phases of the two output signals of the current amplification transformers (or the resistors) to be equal and outputting them in a synthesizer. SOLUTION: When a PIN photodiode 1 receives a light signal, current flows from a cathode-side to an anode-side by the light signal. Current flowing to the PIN photodiode 1 flows to a current amplification transformer 2 connected to the cathode-side and a current amplification transformer 3 which is connected to the anode-side. Current is amplified in the current amplification transformers 2 and 3 and the output signals of the current amplification transformers 2 and 3 are amplified by amplifiers 4 and 5. The phases of the output signals of the amplifiers 4 and 5 are made to be equal in a synthesizer composit 6 and they are synthesized and outputted. Thus, an apparent signal component becomes twice or larger and a noise component does not increase, so that a C/N ratio improves. |
