Active pixel sensor with reduced fixed pattern noise using two active regions
First Claim
Patent Images
1. A method of operating a pixel, the method comprising:
- setting a first active region of the pixel to a predetermined charge level;
transferring charge accumulated in a photoactive region of the pixel during a non-charge integration period to the first active region of the pixel;
transferring charge from the first active region to a power supply node of the pixel;
setting the first active region to the predetermined charge level;
transferring charge accumulated in the photoactive region during a charge integration period to the first active region of the pixel; and
transferring charge from the first active region to a storage node of the pixel.
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Abstract
An image sensor includes pixels each of which is designed to transfer charge, accumulated in a photoactive region of the pixel during a first period, through a second active region of the pixel to a power supply node, and to transfer charge, accumulated in the photoactive region during a second period, through the second active region to a sense node in the pixel. Passing charge through the second active region prior to transferring it either to the power supply node or the sense node can help reduce fixed pattern noise. The image sensor can be operated in snap-shot mode.
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Citations
8 Claims
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1. A method of operating a pixel, the method comprising:
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setting a first active region of the pixel to a predetermined charge level; transferring charge accumulated in a photoactive region of the pixel during a non-charge integration period to the first active region of the pixel; transferring charge from the first active region to a power supply node of the pixel; setting the first active region to the predetermined charge level; transferring charge accumulated in the photoactive region during a charge integration period to the first active region of the pixel; and transferring charge from the first active region to a storage node of the pixel. - View Dependent Claims (2, 3)
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4. A method of operating a pixel comprising a photosensor, the method comprising:
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preparing the pixel for integration by; flooding a first active region of the pixel with charge by raising a voltage on a gate between the first active region and a power supply node of the pixel; lowering the voltage on a gate between the first active region and a charge accumulation region of the pixel; lowering the voltage on a gate between the first active region and a floating diffusion region of the pixel; and transferring a charge from the charge accumulation region to the power supply node; integrating charge with the photosensor to place charge on the charge accumulation region; transferring the integrated charge from the charge accumulation region to the first active region; and generating an output signal from the transferred charge. - View Dependent Claims (5, 6, 7, 8)
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Specification