Solid-State Image Sensor Capacitance Linking for Dynamic Range
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Solution Overview
Problem
Solid-state image sensors face limitations in expanding dynamic range and signal-to-noise (SN) ratio for high-sensitivity reads, despite efforts to connect charge/voltage conversion capacitances and separate regions to enhance capacitance and sensitivity.
Innovation Solution
The solution involves a solid-state image sensor design with linking transistors that control the connection between nodes, allowing for varying capacitance configurations to optimize capacitance values and SN ratio through specific operation modes, enabling greater dynamic range and sensitivity by adjusting the number of linking transistors connected during read operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the linking switch is turned on to connect charge/voltage conversion capacitances, then the dynamic range is expanded, but the capacitance value increases which reduces the charge/voltage conversion coefficient
Solution Approach 1:
The pixel array is divided into multiple pixel blocks, each with independent charge/voltage conversion capacitance control. By segmenting the pixel array and controlling linking switches independently for each block, the system can selectively connect or disconnect capacitances to optimize between dynamic range and conversion coefficient based on imaging conditions.
Solution Approach 2:
The linking switches are designed to be dynamically controllable, allowing the charge/voltage conversion capacitance to be adjusted in real-time during operation. This dynamic adjustment enables the system to switch between high dynamic range mode (linked capacitances) and high sensitivity mode (unlinked capacitances) depending on the imaging requirements.
2Measurement precision
If the linking switch is turned off to separate charge/voltage conversion regions, then the charge/voltage conversion coefficient increases, but the dynamic range is reduced
Solution Approach 1:
By segmenting the pixel array into multiple independently controllable pixel blocks, each block can operate with separated charge/voltage conversion regions to maximize the conversion coefficient when high sensitivity is required, while the overall system maintains the capability to expand dynamic range when needed.
Solution Approach 2:
The system changes the capacitance parameter dynamically by controlling the linking switches. When high sensitivity is needed, the capacitance is kept small (switches off); when dynamic range is needed, the capacitance is increased (switches on). This parameter change resolves the contradiction between conversion coefficient and dynamic range.
3Adaptability or versatility
If multiple linking transistors are used to control capacitance connections, then the capacitance configuration flexibility increases, but the device complexity increases
Solution Approach 1:
The linking transistors are designed to serve multiple functions: they control charge transfer between pixels, manage capacitance linking for dynamic range adjustment, and enable different readout modes. This multi-functionality reduces the need for separate dedicated components, thereby managing complexity while maintaining flexibility.
Solution Approach 2:
By dividing the pixel array into multiple pixel blocks with independent linking transistor control, each block can be optimized separately. This segmentation allows the system to achieve high configurability without requiring a complex global control structure, as each block operates semi-independently with its own linking transistors.
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 allows for improved dynamic range and SN ratio by minimizing capacitance values when necessary and increasing them as needed, effectively enhancing the sensor's ability to handle signal charges and maintain high sensitivity during read operations.
Implementation Method 1
each pixel comprising a photodiode PD as a photoelectric conversion unit
Implementation Method 2
a charge/voltage conversion capacitance CA(n) having a first end electrically connected to the first node Pa(n)
Data Source
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AI summary
A solid-state image sensor includes: a plurality of pixels, each including a photoelectric conversion unit and a charge accumulating unit that accumulates an electric charge from the photoelectric conversion unit; and a connection unit that includes a plurality of linking units each of which electrically connects the charge accumulating units of two adjacent pixels among the plurality of pixels.