| 摘要 |
<P>PROBLEM TO BE SOLVED: To improve the current-voltage conversion accuracy of a current-voltage converter circuit for converting a photo current to a voltage, corresponding to a laser beam output received by a photo diode. <P>SOLUTION: A shunt circuit is constituted of a current mirror circuit composed of e.g. pnp transistors P1, P2, Pa and an operational amplifier OP1, and shunts a photo current IPD from a photo diode PD. Switches SW1, SW2 select either the pnp transistor P1 or P2 according to the variation of the reception photosensitivity of the photo diode in a formed system. After adjusting the photo current IPD to an optimum current for the current-voltage conversion, a voltage converter circuit composed of an operational amplifier OP2 and a resistor R1 converts it to the voltage. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
