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CMOS IMAGE SENSOR HAVING LESS kTC NOISE, RESET TRANSISTOR CONTROL CIRCUIT USED BY THIS IMAGE SENSOR, AND VOLTAGE SWITCHING CIRCUIT USED FOR THIS CONTROL CIRCUIT
CMOS IMAGE SENSOR HAVING LESS kTC NOISE, RESET TRANSISTOR CONTROL CIRCUIT USED BY THIS IMAGE SENSOR, AND VOLTAGE SWITCHING CIRCUIT USED FOR THIS CONTROL CIRCUIT
PROBLEM TO BE SOLVED: To provide a CMOS image sensor reducing a reset noise and a kTC noise due to deviation from a reset voltage.;SOLUTION: This device is applied to the CMOS image sensor in which each pixel circuit of an active motion image sensor array includes a photoelectric conversion element for converting an input light into electric, and a switching transistor for controlling the supply of a reset voltage for resetting the photoelectric conversion element into a predetermined voltage to the photoelectric conversion element. The CMOS image sensor is provided with a control circuit for providing a control signal to be applied to the control electrode of the switching transistor. This control circuit outputs a first voltage far higher than the power source voltage of the CMOS image sensor so that the on-resistance of the switching transistor is satisfactorily smaller in the first half of reset period of the photoelectric conversion element, and the control circuit outputs a second voltage lower than the power source voltage of the CMOS transistor in the second half the reset period of the photoelectric conversion element so that the on-resistance is satisfactorily large. In this way, a cutoff frequency by the on-resistance and the capacity of the photoelectric conversion element is satisfactorily reduced, thereby reducing the reset noise and the kTC noise due to the deviation from the reset voltage.;COPYRIGHT: (C)2006,JPO&NCIPI
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