To provide a current-voltage conversion circuit which prevents the saturation of an operational amplifier at the time of receiving the light of high power, and which can set a limit arbitrarily.
In this circuit, the light is incident on a photodiode 2. When a photocurrent I is generated, a current of mirror ratio as many current decided by resistors 4, 5 through a current mirror circuit 9 is inputted to the operational amplifier 1. In this case, a voltage drop occurs according to the photocurrent I in the resistor 4, but a limiting function will not work if this value is a voltage in which a transistor 8 for limit begins to operation, such as, for example, 0.7 V or lower. However, when the photocurrent I becomes large and the voltage drop in the resistor 4 reaches the voltage in which the transistor 8 begins to operate, the photocurrent I generated in the photodiode 2 is passed to a GND. Consequently, the input current to the amplifier 1 is limited.
| JPH11234055 | NONLINEAR AMPLIFIER |
| JP2848495 | [Title of Invention] Optical Receiver |
FUKUDA HIDEO
CHATO TETSUO
SHIMIZU YUZO
Tomoyasu Sakaguchi
Hiroki Naito