Patent ID: 6933974

Claim:
A CMOS image sensor, comprising: a pixel sensor having a reset mode, the pixel sensor generating reset data in the reset mode, the pixel sensor further generating signal data, the pixel sensor being responsive to energy received externally, for generating the signal data, the pixel sensor producing an amount of photo-charge according to the amount of the received energy and converting the produced photo-charge to the signal data, the signal data having a voltage level depending on the amount of the produced photo-charge; a data I/O line carrying the signal data and the reset data generated in the pixel sensor; a double sampling circuit coupled to the data I/O line for sampling the signal data and the reset data, and driving an output terminal, wherein the double sampling circuit samples the signal data before sampling the reset data; and an output circuit for outputting data related to a voltage level of the output terminal, wherein the double sampling circuit comprises: a first transistor driving the data I/O line to a first reference voltage in response to a read command, and outputting a value related to the signal data; a coupling capacitor coupling a storing node with the data I/O line; a second transistor driving the storing node to a second reference voltage in response to a control signal; and a third transistor transferring a voltage of the storing node to the output terminal in response to a second selecting signal.