Image sensor

Abstract

An image sensor includes a photoelectric device generating an electric charge from light; a feedback device generating a reset voltage using a predetermined reference voltage; and a pixel circuit generating a pixel voltage using the reset voltage and the electric charge, setting the reset voltage to the reference voltage using the feedback device a first period, and outputting the pixel voltage and the reset voltage during a second period.

What is claimed is: 
     
         1 . An image sensor, comprising:
 a pixel array including a plurality of pixels arranged along a plurality of row lines and a plurality of column lines;   a memory device configured to store a reset voltage detected from the plurality of pixels;   a row driver configured to sequentially select a first row line and a second row line among the plurality of row lines during each horizontal period;   a sampling circuit configured to reset first pixels connected to the first row line and detect a reset voltage from the first pixels while the first row line is selected, and detect a pixel voltage from second pixels connected to the second row line while the second row line is selected; and   an arithmetic circuit configured to calculate a difference between the pixel voltage detected from the second pixels and the reset voltage of the second pixels stored in the memory device.   
     
     
         2 . The image sensor of  claim 1 , wherein the arithmetic circuit comprises an analog-to-digital converter, wherein the analog-digital converter converts the reset voltage detected from the first pixels and the pixel voltage detected from the second pixels into a digital value. 
     
     
         3 . The image sensor of  claim 2 , wherein the arithmetic circuit calculates a difference between the pixel voltage detected from the second pixels and the reset voltage of the second pixels stored in the memory device, in a digital domain. 
     
     
         4 . The image sensor of  claim 1 , wherein the pixel array, the memory device, and the arithmetic circuit are alternately stacked in a single package. 
     
     
         5 . The image sensor of  claim 1 , wherein the pixel array comprises m row lines, where m is a natural number greater than or equal to 2, the first row line is provided as a nth row line, and the second row line is provided as an [n+1]th row line, where n is a natural number less than m. 
     
     
         6 . The image sensor of  claim 1 , wherein each of the first pixels and the second pixels comprises:
 a photoelectric device generating an electric charge from light;   a floating diffusion node in which the electric charge is accumulated;   a reset transistor resetting an electric potential of the floating diffusion node to the reset voltage in response to a reset control signal;   a driving transistor generating the pixel voltage according to the electric potential of the floating node; and   a selection transistor outputting the pixel voltage.   
     
     
         7 . The image sensor of  claim 6 , wherein each of the first pixels and the second pixels comprises a feedback device connected to the selection transistor and setting the reset voltage to a predetermined reference voltage. 
     
     
         8 . The image sensor of  claim 6 , wherein the sampling circuit comprises:
 a comparator;   an auto-zero switch connecting an input terminal of the comparator to an output terminal of the comparator; and   a capacitor connected between the input terminal of the comparator and an output terminal of the selection transistor.   
     
     
         9 . The image sensor of  claim 8 , wherein the reset transistor is maintained in a turned on state while the auto-zero switch is closed. 
     
     
         10 . A driving apparatus for driving an image sensor, the driving apparatus comprising:
 a driving circuit configured to drive the image sensor,   wherein the driving circuit sets a reset voltage applied to a first pixel of a first row of the image sensor to a reference voltage during a first period,   wherein the driving circuit outputs the reset voltage and a first pixel voltage of the first pixel during a second period, and   wherein the driving circuit outputs the reset voltage applied to a second pixel of a second row of the image sensor and a second pixel voltage of the second pixel during the first period.   
     
     
         11 . The driving apparatus of  claim 10 , further comprising:
 a first operational amplifier providing the reset voltage based on the reference voltage and outputs from first selection transistors of the image sensor; and   a second operational amplifier detecting the reset voltage and the pixel voltages using outputs from second selection transistors of the image sensor.   
     
     
         12 . The driving apparatus of  claim 11 , further comprising a row driver configured to turn on the first selection transistors and turn off the second selection transistors during the first period, and turn off the first selection transistors and turn on the second selection transistors during the second period.