To provide a light receiving amplifier device provided with an APD (avalanche photodiode) capable of preventing the self-destruction of the APD even when strong light is input and capable of suppressing power consumption.
The light receiving amplifier device is provided with a high voltage generation circuit 11, an APD bias voltage control circuit 12, a current detection circuit 13, an APD 14, and a current drop circuit 15. The high voltage generation circuit 11 applies prescribed bias voltage to the APD 14 and supplies a bias current. The APD bias voltage control circuit 12 suitably holds the APD bias voltage at least in the light receiving level range of the APD and controls the inner amplification factor of the APD 14. The current detection circuit 13 detects a current flowing into the APD 14. When the light receiving level of the APD 14 exceeds a maximum light receiving level on the basis of a current value detected by the current detection circuit 13, the voltage drop circuit 15 drops the output voltage of the high voltage generation circuit 11 until the bias voltage becomes the amplification disabling voltage of the APD 14.
Akinaka Takano
Susumu Iwano
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