Silicon Rich Oxide Image Sensor Pixel Circuit
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Solution Overview
Problem
Conventional image sensors rely on built-in amplifiers, which can be noisy and sensitive to external interference, and their sensitivity is limited by the area of the light sensing component, capacitance, and amplifier gain, making them inefficient in detecting luminance variations.
Innovation Solution
An image sensor design utilizing a light sensing component made of silicon rich oxide material, combined with a first and second transistor, and a diode, which allows for improved luminance detection by varying the voltage level in response to light exposure, simplifying the circuit structure and enhancing sensitivity through capacitive characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional image sensors use built-in amplifiers to amplify photoelectric conversion signals, then the sensing signal is less affected by noise during transmission, but the device complexity increases and manufacturing precision becomes more difficult to maintain
Solution Approach 1:
The patent extracts and removes the built-in amplifier component from each pixel, replacing it with a simplified circuit using transistors and capacitors. This eliminates the complexity and manufacturing difficulties associated with amplifiers while maintaining signal integrity through alternative charge transfer and voltage conversion mechanisms.
Solution Approach 2:
The patent uses a capacitor to store and transfer charge information, effectively copying the signal preservation function of the amplifier without requiring active amplification components. The capacitor-based approach replicates the signal holding capability while avoiding the complexity of amplifier circuits.
2Measurement precision
If the area of the light sensing component is increased to improve sensitivity, then more photo charges are generated, but the device area occupied by each pixel increases
Solution Approach 1:
The patent merges the light sensing component with the capacitor and transistor structures, allowing shared use of space and materials. The silicon-rich oxide layer serves dual purposes as both the light sensing medium and the capacitor dielectric, reducing the total pixel area required while maintaining sensitivity.
Solution Approach 2:
The silicon-rich oxide material performs multiple functions: it acts as the light sensing component, the capacitor dielectric layer, and the charge storage medium. This multi-functionality eliminates the need for separate components, reducing pixel area while maintaining detection sensitivity.
3Measurement precision
If the capacitance of the integrating capacitor is increased to improve sensitivity, then the voltage at the capacitor ends decreases, but the device complexity and manufacturing precision requirements increase
Solution Approach 1:
The capacitor is merged with the light sensing component structure, where the silicon-rich oxide layer serves as both the sensing medium and the capacitor dielectric. This integration eliminates the need for separate capacitor structures, reducing manufacturing complexity while achieving the required capacitance for sensitive detection.
Solution Approach 2:
The silicon-rich oxide layer performs dual functions as both the photodetector active layer and the capacitor insulator. This multi-functional design achieves the necessary capacitance for high sensitivity without requiring complex separate capacitor structures, thereby reducing manufacturing precision requirements.
4Measurement precision
If built-in amplifiers are used in each pixel, then photoelectric conversion signals are amplified, but manufacturing precision becomes more difficult to maintain
Solution Approach 1:
The patent removes the built-in amplifier from the pixel structure, replacing it with passive components (capacitors and transistors) that are easier to manufacture with standard semiconductor processes. This extraction eliminates the manufacturing precision difficulties associated with fabricating sensitive amplifier circuits in each pixel.
Solution Approach 2:
The patent replaces expensive and difficult-to-manufacture amplifier components with simpler, more robust transistor and capacitor structures that can be manufactured using standard, well-established semiconductor fabrication processes, reducing both cost and manufacturing precision requirements.
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
The image sensor effectively detects luminance variations with reduced noise interference and improved sensitivity, leveraging the capacitive properties of the silicon rich oxide material and transistor configuration to enhance voltage output.
Implementation Method 1
the light sensing component generates a voltage drop when sensing light
Implementation Method 2
leveraging the capacitive properties of the silicon rich oxide material to enhance voltage output
Data Source
AI summary
An image sensor includes a light-sensing element, a first transistor, and a second transistor. The light-sensing element has a first end and a second end electrically connected to a select line. The first transistor has a first end electrically connected to a first control line, a control end electrically connected to the first end, and a second end electrically connected to the first end of the light-sensing element. The second transistor has a first end electrically connected to a voltage source, a control end electrically connected to the first end of the light-sensing element, and a second end electrically connected to an output line. The light-sensing element uses the material of silicon rich oxide so that the light-sensing element can sense the luminance variance and have the characteristic of the capacitor for the level boost.