Imaging Pixel Feedback Transistor kTC Noise Reduction
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Solution Overview
Problem
Current imaging devices face challenges in effectively reducing reset noise, particularly kTC noise, which affects image quality.
Innovation Solution
The imaging device incorporates a pixel configuration with a photoelectric converter, charge accumulator, amplification transistor, feedback transistor, current supply, and select transistors, along with a current source/voltage source switching circuit and voltage supply circuits, to manage noise through strategic capacitor connections and voltage control during reset and readout operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If in-pixel feedback is used to reduce reset noise, then reset noise reduction is improved, but device complexity increases
Solution Approach 1:
The patent implements feedback by connecting the feedback transistor between the charge accumulator and the amplification transistor, creating a feedback path that reduces reset noise through in-pixel feedback operations
Solution Approach 2:
The pixel circuit is divided into multiple functional components (photoelectric converter, charge accumulator, amplification transistor, feedback transistor, select transistors, current supply) that work together to achieve noise reduction while managing complexity
2Object-affected harmful factors
If feedback operations are used to suppress kTC noise, then noise reduction is improved, but operation time increases
Solution Approach 1:
The feedback transistor continuously operates during the reset period to provide ongoing noise suppression, ensuring that the feedback action is maintained throughout the necessary time window without requiring additional discrete operations
Solution Approach 2:
The feedback mechanism is activated during the reset operation itself, performing noise cancellation in advance before the actual signal readout begins, thereby reducing the overall time needed for noise-free operation
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 significantly reduces reset noise by suppressing kTC noise through feedback operations and minimizing parasitic capacitance, leading to improved image quality and faster signal convergence.
Implementation Method 1
a photoelectric converter that converts light into a signal charge
Implementation Method 2
suppressing kTC noise through feedback operations
Data Source
AI summary
An imaging device is provided with an amplification transistor having a gate connected to a charge accumulator, a feedback transistor of which the source or drain is electrically connected to the charge accumulator and the other is connected to the source or drain of the amplification transistor, a current supply that supplies a current to a first node, a first select transistor of which the source or drain is connected to the other of the amplification transistor, a second select transistor of which the source or drain is connected to the source or drain of the amplification transistor, a current source/voltage source switching circuit that selectively connects a current source or a first voltage supply circuit to the other of the first select transistor, and a second voltage supply circuit connected to the other of the second select transistor.