Partial Pixel Binning for CMOS Image Sensors
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Solution Overview
Problem
Modern image sensors face challenges in achieving high frame rates, low read noise, and high dynamic range while minimizing power consumption, as increasing the number of ADCs or reducing pixel readout time leads to increased power consumption.
Innovation Solution
The implementation of novel pixel binning schemes in image sensors, where pixels sharing a common readout structure are binned and read out using different exposure times, allowing for concurrent digital data conversion and reducing readout noise without increasing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the number of ADCs is increased to improve frame rate and reduce read noise, then readout performance is improved, but power consumption increases
Solution Approach 1:
Multiple pixels sharing a common readout structure and ADC are merged into binning groups. Pixels within each group are read out simultaneously through the shared readout path, reducing the total number of readout operations required while maintaining readout performance. This merging approach allows fewer ADCs to serve more pixels, thereby reducing power consumption.
Solution Approach 2:
The pixel array is segmented into multiple binning groups, where each group shares a common readout structure. This segmentation allows parallel readout operations across different groups while using a reduced number of ADCs, achieving the desired frame rate and read noise performance without proportionally increasing power consumption.
2Productivity
If the readout time per pixel is reduced to improve frame rate, then productivity is improved, but readout noise increases
Solution Approach 1:
Multiple pixels are merged into binning groups that share common readout structures. By reading out multiple pixels simultaneously through the shared path, the effective readout time per pixel group is reduced, enabling higher frame rates. The shared readout structure also averages out noise across multiple pixels, reducing readout noise while maintaining productivity.
3Reliability
If pixel binning is applied to reduce readout noise, then readout noise is reduced, but optical resolution is degraded
Solution Approach 1:
The pixel array is segmented into binning groups that can be read out independently. This segmentation allows selective binning where readout noise reduction is prioritized in certain regions while maintaining finer resolution in other regions, achieving a balance between readout noise performance and optical resolution.
Solution Approach 2:
Different binning configurations can be applied to different regions of the pixel array based on local requirements. Regions requiring low readout noise can use higher binning factors, while regions requiring high resolution can use lower binning factors, achieving spatially varying optimization of readout noise and resolution.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables faster readout and lower readout noise while maintaining power efficiency, achieving real-time high dynamic range and reducing optical resolution trade-offs.
Implementation Method 1
The basic function of a modern CMOS image sensor (CIS) is to capture photons that are converted into electrons in a photodiode array
Data Source
AI summary
An image sensor includes a pixel array comprising a plurality of pixels, a color filter array comprising a plurality of color filter clusters overlying the pixel array, and readout circuitry configured to concurrently provide the pixels sharing the common filter cluster and having a first exposure time to a readout line for digital data conversion. Each of the color filter clusters includes a group of same color filters, and pixels sharing a common color filter cluster have different exposure times.