| 摘要 |
A PD(Photo Diode) connection circuit is provided to generate a predetermined reference voltage which is regardless of input noise incoming from power to use the generated reference voltage, thereby maximally suppressing a wrong operation owing to the noise incoming from the power. A reference voltage generator(202) generates the first reference voltage. One terminal of a PD is connected to the first power voltage. One terminal of a trans impedance resistor is connected to the first reference voltage while the other terminal is connected to the other terminal of the PD. A signal of a common terminal of the trans impedance resistor and the PD is applied to one input terminal of the first amplifier(201), and the second reference voltage is applied to the other terminal thereof.
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