CMOS Image Sensor Layout With Shared Floating Diffusion Nodes
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Solution Overview
Problem
Existing CMOS image sensors face challenges in optimizing signal processing and noise reduction while maintaining miniaturization and low power consumption, particularly in applications with limited battery capacity.
Innovation Solution
The image sensor incorporates a substrate with photoelectric conversion elements arranged in specific patterns, connecting floating diffusion regions of multiple elements to reduce noise and improve signal processing efficiency, and utilizes a color filter layer with a Bayer pattern to enhance light reception and reduce crosstalk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If floating diffusion regions of multiple photoelectric conversion elements are connected to reduce noise, then signal-to-noise ratio is improved, but device complexity increases due to additional connection structures
Solution Approach 1:
Multiple floating diffusion regions are merged into a single common floating diffusion region, allowing multiple photoelectric conversion elements to share the same signal processing node. This reduces noise through signal averaging while simplifying the overall structure by eliminating the need for separate readout circuits for each element.
Solution Approach 2:
The common floating diffusion region serves multiple functions: it acts as the signal collection node for multiple photoelectric conversion elements, provides noise reduction through shared capacitance, and simplifies the readout architecture by serving as a universal output node for grouped elements.
2Reliability
If photoelectric conversion elements are arranged in specific patterns with color filters to enhance light reception, then imaging performance is improved, but manufacturing precision requirements increase
Solution Approach 1:
The photoelectric conversion elements are segmented into groups, with each group associated with a specific color filter. This segmentation allows for systematic arrangement patterns (such as Bayer patterns) that optimize light reception while providing clear fabrication guidelines for achieving the required spatial relationships between elements and filters.
Solution Approach 2:
Different regions of the sensor array are assigned different color filter types (red, green, blue) according to specific patterns, creating local variations in optical properties. This local quality differentiation enhances overall imaging performance by enabling color discrimination while the periodic nature of the pattern provides manufacturing tolerance.
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
The solution enhances image quality by reducing noise and improving signal-to-noise ratio, allowing for efficient signal processing and miniaturization without increasing power consumption.
Implementation Method 1
a first substrate including a first surface and a second surface opposite each other, and a plurality of photoelectric conversion elements between the first surface and the second surface
Data Source
AI summary
An image sensor is provided. The image sensor includes: a first substrate including a first surface and a second surface opposite each other, and a plurality of photoelectric conversion elements between the first surface and the second surface; and a color filter provided on the second surface of the first substrate and including a first color filter, a second color filter, and a third color filter. The first color filter is provided on 36 photoelectric conversion elements among the plurality of photoelectric conversion elements. The 36 photoelectric conversion elements are arranged in six columns extending in a first direction and in six rows extending in a second direction that crosses the first direction. Floating diffusion regions of 12 photoelectric conversion elements among the 36 photoelectric conversion elements are connected to each other.