Charge-Pump Voltage Generation for Compact Image Sensor SNR
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Solution Overview
Problem
The miniaturization of imaging devices, such as CCD-type imaging devices, is limited due to the requirement for multiple power source voltages, and the reduction in pixel size leads to a decrease in the amount of electric charge stored, resulting in a deteriorated signal-to-noise ratio and image quality.
Innovation Solution
A voltage generation circuit that includes a booster circuit with a capacitance element and a transistor, a control buffer circuit, and a driving buffer circuit, capable of generating a higher first voltage than the power source voltage or a lower second voltage than the ground voltage, allowing for improved voltage control and reduced circuit complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If pixel size is reduced to enable miniaturization, then device size is reduced, but signal-to-noise ratio deteriorates and image quality deteriorates
Solution Approach 1:
The patent changes the voltage parameter by introducing a voltage generation circuit that produces multiple voltages (power source voltage, ground voltage, first voltage higher than power source voltage, and second voltage lower than ground voltage) to optimize photo diode operation and maintain signal-to-noise ratio even when pixel size is reduced
2Measurement precision
If multiple power source voltages are used to improve image quality, then signal-to-noise ratio is improved, but device complexity increases
Solution Approach 1:
The voltage generation circuit serves multiple functions: it generates the power source voltage, ground voltage, first voltage (higher than power source voltage), and second voltage (lower than ground voltage) all within a single integrated circuit, eliminating the need for separate voltage supply systems and reducing overall device complexity
Solution Approach 2:
The patent introduces a voltage generation circuit as an intermediary component that automatically generates the necessary multiple voltages from a single power source, mediating between the simple single-voltage input and the complex multi-voltage requirements of the imaging device
3Measurement precision
If higher voltage is used to increase electric charge storage, then signal-to-noise ratio is improved, but power consumption increases
Solution Approach 1:
The voltage generation circuit dynamically switches between different voltages (power source voltage, first voltage, and second voltage) based on operational requirements, allowing the system to use higher voltage only when needed for charge storage while consuming lower voltage during other operations, thereby optimizing power consumption
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 proposed voltage generation circuit enables the generation of necessary voltages for imaging devices without increasing circuit complexity, thereby facilitating miniaturization and improving image quality by maintaining or enhancing the signal-to-noise ratio.
Implementation Method 1
a booster circuit including a capacitance element and a transistor
Implementation Method 2
The booster circuit is a charge-pump-type booster circuit including a plurality of pumping packets
Data Source
AI summary
A voltage generation circuit includes a booster circuit, a control buffer circuit, and a driving buffer circuit. The booster circuit includes a capacitance element and a transistor. The booster circuit generates a higher first voltage than the power source voltage, and the control buffer circuit controls the transistor by using a third voltage that is lower than the first voltage and is higher than a ground voltage. Alternatively, the booster circuit generates a lower second voltage than the ground voltage, and the control buffer circuit controls the transistor by using a fourth voltage that is higher than the second voltage and is lower than or equal to the ground voltage.