| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an optical current/voltage conversion circuit with improved optical input range of a light receiving element. <P>SOLUTION: In this circuit, one end of a photodiode 1 is subjected to reverse bias connection with an input end 3 of an amplifier 2 in which an output voltage is feed-backed to the input end 3 through a feed-back resistor 11, and the optical current output of the photodiode 1 is subjected to voltage conversion. An n-channel type MOSFET 12 as a clamp element for setting the clamped value of an output voltage, a first current mirror circuit CM1 turned on by boosting of the output voltage, and a second mirror circuit CM2 turned on by interlocking with the first current mirror circuit CM1 are provided, and a shortfall amount of current performance of the amplifier 2 at the input time of strong light is fed from a second power-supply terminal VH and the output voltage is clamped below a prescribed value so that saturation of the amplifier 2 can be prevented. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
