Two-Stage Imaging Element for Global Shutter Noise Cancellation
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Solution Overview
Problem
Global shutters face challenges with kTC noise and output offset due to random noise generation and element characteristic variations, making it difficult to achieve high accuracy and efficiency in image sensing, especially when compared to rolling shutters.
Innovation Solution
An imaging element with a two-stage amplifier configuration, including a photoelectric conversion element, first and second amplification elements, an offset element, and reset elements, where the offset element is used to adjust the output signal to a reference level, reducing noise and offset through correlated double sampling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a global shutter is used to align exposure times for all pixels, then imaging accuracy for high-speed moving subjects is improved, but output offset control becomes difficult due to kTC noise and element characteristic variations
Solution Approach 1:
The pixel amplifier is divided into two separate amplification stages: a first amplification element and a second amplification element. This segmentation allows each stage to be independently reset and controlled, enabling better management of kTC noise and offset variations in global shutter mode.
Solution Approach 2:
A reset element is provided for each amplification element to perform preliminary resetting before signal amplification. The first reset element resets the first amplification element, and the second reset element resets the second amplification element, thereby eliminating kTC noise before it affects the final output signal.
2Reliability
If a two-stage amplifier configuration is used with separate reset elements, then noise and offset are reduced, but device complexity increases
Solution Approach 1:
The two amplification stages are integrated within a single pixel structure, sharing common components such as the photoelectric conversion element and signal routing pathways. This merging approach reduces the overall complexity increase while maintaining the benefits of dual-stage amplification and resetting.
Solution Approach 2:
The first and second amplification elements serve multiple functions: they provide signal amplification, enable correlated double sampling, and allow independent resetting to eliminate kTC noise. This multi-functionality justifies the additional complexity by delivering multiple performance benefits from a single structural addition.
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 noise and output offset, enabling improved accuracy and efficiency in global shutter operation by canceling kTC noise and element characteristic variations, similar to rolling shutters, while maintaining high-speed global reset capabilities.
Implementation Method 1
a photoelectric conversion element
Data Source
AI summary
The present technology relates to an imaging element that can reduce noise. The imaging element includes: a photoelectric conversion element; a first amplification element that amplifies a signal from the photoelectric conversion element; a second amplification element that amplifies an output from the first amplification element; an offset element provided between the first amplification element and the second amplification element; a first reset element that resets the first amplification element; and a second reset element that resets the second amplification element. The offset element is a capacitor. A charge is accumulated in the offset element via a feedback loop of an output from the second amplification element, and an offset bias is generated. The present technology can be applied to an imaging element.