CMOS image sensors implementing full frame digital correlated double sampling with global shutter
First Claim
1. An image sensing device comprising:
- a two-dimensional array of light sensing elements, each light sensing element comprising a photodiode and a plurality of control transistors, each photodiode generating an output signal indicative of an intensity level of light impinging on the photodiode, and the plurality of control transistors being configured to control reset, charge transfer and row select operations of the array of light sensing elements;
a timing and control circuit configured to generate control signals for the plurality of control transistors in each light sensing element in the array, the control signals controlling reset, light integration, charge transfer and readout operations of the array of light sensing elements;
one or more analog-to-digital converters respectively coupled to columns of the array of light sensing elements and configured to digitize output signals read out from the array of light sensing elements to generate digital output pixel values; and
a memory configured to store at least one frame of digital output pixel reset values,wherein the timing and control circuit is configured to reset the light sensing elements in the array at substantially the same time and to read out respective pixel reset values associated with the light sensing elements, the pixel reset values being stored in the memory; and
the timing and control circuit is further configured to control the array of light sensing elements to integrate incident light at substantially the same time and for substantially the same time duration and to read out light dependent pixel values associated with the light sensing elements; and
wherein the pixel reset values are cancelled from the corresponding light dependent pixel values for each of the light sensing elements in the array to generate correlated double sampling (CDS) corrected digital output pixel values.
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Abstract
An active pixel CMOS image sensor implements full frame digital correlated double sampling (CDS) with global shutter where all the pixels in the image sensor are reset at substantially the same time and all the pixels in the image sensor integrate incident light at substantially the same time and for substantially the same time duration and correlated double sampling cancellation is performed in the digital domain. In one embodiment, the image sensing device includes an array of light sensing elements, a timing and control circuit and analog-to-digital converters. The timing and control circuit is operative to reset the light sensing elements in the array and to control the array of light sensing elements to integrate incident light. The pixel reset values are cancelled from the corresponding light dependent pixel values for each of the light sensing elements to generate correlated double sampling (CDS) corrected digital output pixel values.
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Citations
19 Claims
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1. An image sensing device comprising:
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a two-dimensional array of light sensing elements, each light sensing element comprising a photodiode and a plurality of control transistors, each photodiode generating an output signal indicative of an intensity level of light impinging on the photodiode, and the plurality of control transistors being configured to control reset, charge transfer and row select operations of the array of light sensing elements; a timing and control circuit configured to generate control signals for the plurality of control transistors in each light sensing element in the array, the control signals controlling reset, light integration, charge transfer and readout operations of the array of light sensing elements; one or more analog-to-digital converters respectively coupled to columns of the array of light sensing elements and configured to digitize output signals read out from the array of light sensing elements to generate digital output pixel values; and a memory configured to store at least one frame of digital output pixel reset values, wherein the timing and control circuit is configured to reset the light sensing elements in the array at substantially the same time and to read out respective pixel reset values associated with the light sensing elements, the pixel reset values being stored in the memory; and
the timing and control circuit is further configured to control the array of light sensing elements to integrate incident light at substantially the same time and for substantially the same time duration and to read out light dependent pixel values associated with the light sensing elements; andwherein the pixel reset values are cancelled from the corresponding light dependent pixel values for each of the light sensing elements in the array to generate correlated double sampling (CDS) corrected digital output pixel values. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A method in an image sensing device, comprising:
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providing a two-dimensional array of light sensing elements, each light sensing element comprising a photodiode and a plurality of control transistors, each photodiode generating an output signal indicative of an intensity level of light impinging on the photodiode, and the plurality of control transistors being configured to control reset, charge transfer and row select operations of the array of light sensing elements; resetting the array of light sensing elements at substantially the same time; reading out the pixel reset values associated with the light sensing elements; storing the pixel reset values; integrating charges at the photodiodes of the array of light sensing elements indicative of incident light at substantially the same time and for substantially the same time duration; reading out the light dependent pixel values associated with the light sensing elements; and cancelling the pixel reset values from the corresponding light dependent pixel values for each of the light sensing elements in the array to generate correlated double sampling (CDS) corrected digital output pixel values. - View Dependent Claims (18, 19)
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Specification