| 摘要 |
PURPOSE:To fluctuate the output of a voltage amplifying circuit around a predetermined reference voltage between GND and the voltage of a power source, by feeding back the output of a peak holding circuit to the input side of the voltage amplifying circuit. CONSTITUTION:After optical input is detected by a light detection element 1, the output of a current/voltage converting circuit 14 is amplified by a voltage amplifying circuit 15. That is, the peak value of the output voltage of the voltage amplifying circuit 15 is held to a peak holding circuit 11 and the output thereof is fed back to the input side of the voltage amplifying circuit 15 through a resistor 13 of which the resistance value is properly selected with respect to the resistance value of a resistor 6. By this method, the output of the voltage amplifying circuit 15 fluctuates around voltage VA. The output of the voltage amplifying circuit 15 is compared on the basis of the voltage VA by a voltage comparator 12 to obtain digital output as shown by d.
|
