| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a photocurrent-voltage conversion circuit for attempting to improve a strong light input range of circuit operation and realize stability/rapidity of an output so that even if an input/outpu voltage of an amplifier 2 is lower than a threshold value of a clamp MOSFET, the amplifier 2 in the photocurrent-voltage conversion circuit of a received light IC does not run out of drive current. <P>SOLUTION: A circuit performs voltage conversion with an photocurrent output of a photodiode 1 by reverse bias connecting a terminal of the photodiode 1 to an input terminal 3 of the amplifier 2 to return output voltage to the input terminal 3 via a resistor 11. In the circuit, the amplifier 2 is constituted by direct current connecting inverting amplification stages of the three stages identical constructions. A Pch type MOSFET 12 is connected in parallel to the resistor 11, its gate is connected to an inverting amplification stage output terminal 13, and current flowing through each of voltage clamp MOSFET 14, 15 and 16 which are inserted between a constant current source output and an earth of each amplifier stage is made smaller at the last stage than other stages or deleted. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
