| 摘要 |
A photodiode (PD) produces signal current output corresponding to the amount of received light. An integrator circuit (10) stores a charge corresponding to the signal current and produces a signal voltage corresponding to the amount of the stored charge. In a CDS circuit (20), the signal voltage from the integrator circuit (10) is applied to a capacitor (C21), and a charge corresponding to the amount of the change of the applied voltage is stored in one selected from capacitors (C22, C23) by switches (SW21 to SW23). A differential amplifier (30) determines the difference in charge stored in the capacitors (C22, C23) of the CDS circuit (20), and produces a signal voltage corresponding to the difference.
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