| 摘要 |
PURPOSE: To obtain the light receiving amplifier in which a DC current component of a light receiving current is sufficiently eliminated and the adoption of a low power supply voltage is attained. CONSTITUTION: A cathode of a photo diode 4 whose anode connects to ground GND is connected to an inverting input terminal of a head amplifier 1. A feedback resistor Rf is connected between an output terminal and the inverting input terminal of the head amplifier 1. An output voltage vo from the head amplifier 1 is fed back to the inverting input terminal of the head amplifier 1 via 1st and 2nd low pass filters 2, 3 connected in series in two stages. The DC current component of the light receiving current is sufficiently eliminated by the 1st and 2nd low pass filters 2, 3 connected in series in two stages. Furthermore, the resistance of a resistor R3 being a feedback resistor is selected small and the power supply voltage is selected lower by the reduction in the voltage drop across the resistor R3. |
