Image Sensor Pixel Architecture Cross-Coupling Reset Gate Interference
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Solution Overview
Problem
Existing image sensors suffer from characteristic degradation due to interference between pixel transistors, specifically between transfer and reset gates, which increases the signal-to-noise ratio (SNR) and degrades operation characteristics, and this issue is challenging to address without altering the layout of these gates.
Innovation Solution
The image sensor architecture electrically isolates the floating diffusion node from the reset transistor in each pixel unit and couples the floating diffusion node of one pixel unit to the reset transistor of an adjacent pixel unit, thereby increasing the electrical distance between transfer and reset gates without changing their layout, preventing interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the floating diffusion node is electrically coupled to the reset transistor in the same pixel unit, then the reset function is achieved, but interference between transfer and reset gates occurs causing characteristic degradation
Solution Approach 1:
The patent divides the reset function across multiple pixel units by electrically coupling the floating diffusion node of a first pixel unit to the reset transistor of a second adjacent pixel unit. This segmentation separates the transfer gate and reset gate operations in space, preventing their interference while maintaining the necessary reset functionality through cross-pixel electrical coupling.
Solution Approach 2:
The patent introduces an intermediary electrical connection between adjacent pixel units, where the floating diffusion node of one pixel unit serves as the intermediary to connect to the reset transistor of another pixel unit. This intermediary connection enables the reset function while physically separating the interfering gate fields.
2Object-generated harmful factors
If the layout of transfer and reset gates is altered to increase electrical distance, then gate interference is reduced, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent merges the reset function across adjacent pixel units by sharing reset transistor control between neighboring pixels. This merging approach maintains a regular, simple layout within each pixel unit while achieving the electrical distance needed to reduce gate interference through the cross-pixel coupling architecture.
Solution Approach 2:
The patent resolves the layout constraint by moving the reset connection to another dimension - specifically, coupling to an adjacent pixel unit in the pixel array rather than within the same pixel unit. This dimensional shift in the electrical connection path increases the effective electrical distance between transfer and reset gates without complicating the in-pixel layout.
3Object-generated harmful factors
If the floating diffusion node is electrically coupled to the reset transistor of an adjacent pixel unit, then gate interference is prevented, but manufacturing precision requirements increase
Solution Approach 1:
The patent creates a universal coupling structure where the floating diffusion node serves dual functions: as the charge storage node for its own pixel unit and as the electrical connection point to the reset transistor of an adjacent pixel unit. This multi-functional design standardizes the coupling interface, reducing manufacturing precision requirements through repeatability.
Solution Approach 2:
The patent changes the electrical connection parameters by establishing fixed, predetermined coupling relationships between adjacent pixel units. By defining specific coupling configurations (e.g., always coupling pixel (i,j) to pixel (i+1,j) or (i,j+1)'), the patent creates manufacturable, repeatable structures that reduce precision requirements compared to arbitrary or optimized individual connections.
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 solution effectively prevents characteristic degradation caused by interference between transfer and reset gates, maintaining improved SNR and operation characteristics without altering the pixel transistor layout, and also addresses non-uniform interference from varying gate distances.
Implementation Method 1
a light receiver suitable for generating photocharge in response to incident light
Data Source
AI summary
An image sensor may include a pixel array in which a plurality of pixel units are arranged in a matrix structure. Each of the pixel units may include a light receiver suitable for generating photocharge in response to incident light, a floating diffusion node electrically coupled to an end of the light receiver, and a reset transistor electrically isolated from the floating diffusion node, wherein a floating diffusion node of a first pixel unit among the plurality of pixel units is electrically coupled to a reset transistor of a second pixel unit adjacent to the first pixel unit among the plurality of pixel units.