Imaging Device Shield Electrode kTC Noise Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current imaging devices face challenges in reducing kTC noise, particularly at the reset time, due to coupling capacitance between the charge storage node and feedback signal lines, which affects image quality.
Innovation Solution
The design incorporates a specific layout where the charge storage region is positioned to avoid overlap with the feedback line, and a second capacitor with a larger electrode area is placed to further reduce coupling capacitance, utilizing a shield electrode configuration to minimize noise interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the feedback signal line is arranged close to the charge storage node to reduce wiring length, then device complexity is reduced, but coupling capacitance between the feedback signal line and charge storage node increases, leading to increased kTC noise
Solution Approach 1:
A shield electrode is introduced as an intermediary element positioned between the feedback signal line and the charge storage node. This shield electrode acts as a mediator that electrically shields the charge storage node from the feedback signal line, reducing the coupling capacitance between them while allowing the feedback signal line to maintain its routing path.
Solution Approach 2:
The harmful coupling capacitance effect is extracted and isolated by introducing the shield electrode. The shield electrode specifically targets and addresses the coupling between the feedback signal line and charge storage node, separating the harmful electromagnetic interaction from the functional signal transmission path.
2Object-affected harmful factors
If shield layers are added between output lines to reduce crosstalk, then noise reduction is improved, but device complexity and manufacturing steps increase
Solution Approach 1:
The shield electrode is integrated into the existing pixel structure and serves multiple functions: it reduces coupling capacitance between the feedback signal line and charge storage node, provides shielding against crosstalk from adjacent pixels, and can be formed using the same manufacturing processes as other electrodes in the device, thereby avoiding significant increases in device complexity.
Solution Approach 2:
The shield electrode configuration merges the noise reduction function with the existing electrode structure. By forming the shield electrode from the same conductive material layers used for other electrodes in the pixel circuit, the solution combines multiple functions into a unified structure that reduces complexity compared to adding separate dedicated shield layers.
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 effectively reduces kTC noise by minimizing coupling capacitance and crosstalk, leading to improved image quality and noise suppression in imaging devices.
Implementation Method 1
a photoelectric converter that converts incident light into signal charge
Data Source
AI summary
An imaging device includes first and second pixels, arranged in a first direction, each of which includes: a photoelectric converter converting incident light into signal charge; an impurity region, in a semiconductor substrate, coupled to the photoelectric converter; a first transistor having a first gate coupled to the impurity region, and first source and drain; and a second transistor having second gate, source and drain. One of the second source and the second drain is the impurity region, and another is coupled to the first source or the first drain. The imaging device further includes a signal line, coupled to the first source or the first drain, and extends along the first direction and overlaps with both of the first and second pixels. The signal line is located on an opposite side from the impurity region across a center line of the first pixel.