Signal read circuit for mos type image sensor

Abstract

Abstract PURPOSE:To accurately read the DC component of a signal by providing a 1st operational amplifier which converts input signal charges into a voltage and a 2nd operational amplifier which subtracts a specific voltage from the output voltage of the 1st operational amplifier. CONSTITUTION:A current corresponding to signal charges accumulated in the stray capacity of a photodiode 19 flows to an output line 29 and is converted into a voltage by an operational amplifier 32. The signal outputted by the amplifier 32 is sent to an operational amplifier 35, where the bias voltage VB of the amplifier 32 is subtracted and the resulting voltage is amplified. Large noise due to the on-off operation of a vertical MOS switch is superposed upon output signal of the amplifier 35. The output signal of the amplifier 35 is integrated by an integrating capacitor 40 so as to remote the noise. A sampling switch 42 is turned on at the timing where the noise is canceled by the integration to lead out a signal corresponding to the quantity of light incident on the diode 19. A reset switch 41 is turned on after the effective signal is led out to discharge the capacitor 40.

Inventors

• 👤 Rokusaburo Kaneko
• 👤 金子　六三郎
• 👤 Kenji Suzuki
• 👤 賢治 鈴木

Bibliographic Details