| 摘要 |
PURPOSE:To improve the sensitivity of a light receiver by setting the value of an impedance element connected to an avalanche photodiode (APD) at a value so that the signal to noise ratio including the respective noises due to the non-linear responses of intrinsic APD may become maximum. CONSTITUTION:A resistor 9 is connected as a load to an APD 8. The value of the resistance of the resistor 9 is so selected that the distortion noise, shot noise and thermal noise due to non-linear response of the APD 8 may be minimized. A high voltage DC power supply 10 applies a reverse bias voltage to the APD 8 to occur avalanche effect, and an amplifier 11 amplifies a signal voltage generated at a connecting point d. |
