Photosensor Back Gate Threshold Control for High Resolution Imaging
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Solution Overview
Problem
Current semiconductor devices with photosensors face challenges in accurately converting light into electric signals across a wide range of light intensities without blurring or distortion, especially when imaging fast-moving objects, and they often consume high power.
Innovation Solution
A semiconductor device is designed with a photosensor comprising a photodiode, a first transistor with a back gate for adjusting threshold voltage, and a second transistor using an oxide semiconductor for low off-current, allowing for multiple readings of stored charge while maintaining constant potential, enabling high-resolution imaging across varying light intensities with low power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional photosensor circuit is used to convert light into electric signals, then the conversion can be performed, but the measurement precision and reliability deteriorate when imaging fast-moving objects due to blur or distortion
Solution Approach 1:
The patent applies preliminary action by performing multiple readings of the charge stored in the first transistor's gate before final image processing. The charge is read multiple times with different back gate potentials applied to the first transistor, allowing the system to capture the light signal multiple times before the object moves significantly, thereby preventing blur or distortion in the final image.
2Adaptability or versatility
If the potential of the back gate of the first transistor is changed to adjust threshold voltage, then the adaptability to different light intensities is improved, but the device complexity increases
Solution Approach 1:
The patent applies parameter changes by varying the back gate potential of the first transistor to dynamically adjust its threshold voltage. This allows the photosensor to adapt to different light intensities by changing the electrical parameter (threshold voltage) of the transistor, enabling accurate conversion of both weak and strong light signals into electric signals without requiring complex additional circuitry.
3Measurement precision
If multiple readings are performed to improve measurement precision, then the imaging resolution is improved, but the power consumption increases
Solution Approach 1:
The patent applies continuity of useful action by performing multiple readings of the stored charge continuously without requiring additional light exposure or resetting the photodiode between readings. The charge accumulated from a single light exposure event is read multiple times with different back gate potentials, maintaining continuous useful action from the initial light capture while achieving high-resolution imaging with reduced power consumption compared to conventional methods.
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 device effectively converts light into electric signals with high resolution and low power consumption, capable of imaging fast-moving objects without blur, and operates efficiently across a wide range of light intensities.
Implementation Method 1
the photodiode has a function of generating an electric signal in accordance with the intensity of light
Data Source
AI summary
A semiconductor device including photosensor capable of imaging with high resolution is disclosed. The semiconductor device includes the photosensor having a photodiode, a first transistor, and a second transistor. The photodiode generates an electric signal in accordance with the intensity of light. The first transistor stores charge in a gate thereof and converts the stored charge into an output signal. The second transistor transfers the electric signal generated by the photodiode to the gate of the first transistor and holds the charge stored in the gate of the first transistor. The first transistor has a back gate and the threshold voltage thereof is changed by changing the potential of the back gate.