Shared-Pixel Image Sensor Layout for Fast High-Resolution Readout
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Solution Overview
Problem
The challenge of maintaining fast operation characteristics in CMOS image sensors as pixel size decreases and pixel count increases, particularly in high-resolution imaging applications.
Innovation Solution
The design of an image sensor with a pixel array that includes first and second pixel groups sharing reset and source follower transistors, connected by a dual conversion transistor, and separated by a pixel separation structure to prevent crosstalk, while using a shared floating diffusion region for efficient charge accumulation and signal processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pixel size is decreased and pixel count is increased to achieve high-resolution imaging, then image resolution is improved, but operation speed of transistors deteriorates
Solution Approach 1:
The pixel array is divided into first and second pixel groups that share common transistors (reset transistor, source follower transistor, selection transistor). This segmentation allows reduction of transistor size within each group while maintaining functional performance through sharing, thereby preserving operation speed despite smaller pixel dimensions.
Solution Approach 2:
Adjacent pixels of different color types (first color and second color) share common transistors including the reset transistor, source follower transistor, and selection transistor. This merging reduces the total number of transistors per pixel, allowing smaller transistor dimensions and maintaining fast operation characteristics in high-resolution configurations.
2Measurement precision
If pixels are placed closer together to increase pixel density, then image resolution is improved, but crosstalk between pixels increases
Solution Approach 1:
A pixel separation structure is extracted and positioned between the first and second pixel groups. This separation structure physically isolates adjacent pixels, preventing optical and electrical crosstalk while allowing the pixels to be densely packed for high-resolution imaging.
3Quantity of substance
If transistors are reduced in size to fit more pixels, then pixel density is improved, but transistor performance deteriorates
Solution Approach 1:
The shared transistors (reset transistor, source follower transistor, selection transistor) serve multiple pixels simultaneously. Each transistor performs the same function for multiple pixels, allowing the use of smaller, simpler transistor designs that maintain adequate performance while enabling higher pixel counts in the same area.
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 configuration maintains fast operation characteristics and reduces crosstalk between pixels, enhancing image quality and processing efficiency in high-resolution imaging.
Implementation Method 1
The photoelectric conversion portion may generate an electrical signal that varies depending on the amount of incident light
Data Source
AI summary
An image sensor may include a first pixel configured to detect a first color, a second pixel configured to detect a second color different from the first color, a first active region located in the first pixel, and a second active region located in the second pixel, where the first active region and the second active region are directly connected to each other.