Image Sensor Column-Line Merging for Lower Transfer Noise
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Image sensors face challenges in reducing output voltage fluctuation, which affects noise characteristics, especially as the number of pixels increases and pixel area decreases.
Innovation Solution
The image sensor design includes active and inactive pixel regions, with inactive pixels having switch transistors that connect column lines to each other, reducing voltage fluctuations by canceling out voltage changes during charge transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of pixels is increased and pixel area is decreased, then the resolution is improved, but the noise characteristics deteriorate due to increased output voltage fluctuation
Solution Approach 1:
Multiple column lines are electrically connected and merged into a single common column line during the transfer period. This combining of previously separate signal paths reduces voltage fluctuation by distributing the capacitive load and stabilizing the output voltage level, thereby improving noise characteristics while maintaining high pixel density
2Reliability
If column lines are connected to each other, then the voltage fluctuation is reduced, but the device complexity increases due to additional connection wiring
Solution Approach 1:
The connection between column lines is activated periodically only during the transfer period when voltage fluctuation occurs, rather than being permanently connected. This time-selective connection approach reduces voltage fluctuation when needed while minimizing the impact on device complexity by using existing wiring structures
3Reliability
If inactive pixel region is added for voltage stabilization, then the noise characteristics are improved, but the area of active pixel region is reduced
Solution Approach 1:
The inactive pixel region serves multiple functions: it provides a stable reference voltage level during transfer operations to reduce noise, and simultaneously maintains the same physical dimensions as the active pixel region to preserve overall sensor area efficiency. The switch transistors in inactive pixels enable column line connection without sacrificing active pixel density
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 significantly reduces voltage fluctuations on column lines, thereby improving the noise characteristics and overall performance of the image sensor.
Implementation Method 1
Each of the plurality of pixels includes a photoelectric element
Data Source
AI summary
An image sensor includes a substrate including an active pixel region and an inactive pixel region, having a smaller area than the active pixel region; a plurality of active pixels in the active pixel region, each of the plurality of active pixels including a first transfer transistor, a first reset transistor, a first driving transistor, and a first selection transistor; and a plurality of inactive pixels in the inactive pixel region, each of the plurality of inactive pixels including a second transfer transistor, a second reset transistor, a second driving transistor, a second selection transistor, and a switch transistor connected to a node between the second driving transistor and the second select transistor. The plurality of switch transistors, included in the plurality of inactive pixels, are connected to each other by a connection wiring.