Signal Amplifying Circuit With Threshold Compensation for Weak-Light Sensing
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Solution Overview
Problem
Conventional touchless touchscreens experience low response accuracy under weak light due to bad uniformity in signal amplification caused by differences in threshold voltages across transistors, leading to poor amplification effects.
Innovation Solution
A signal amplifying circuit is designed with a reset module, optoelectronic device, and positive feedback module, including inverters with compensation transistors and storage capacitors, which adjust the threshold voltage of driving transistors to ensure uniform signal amplification across different transistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional inverter amplification is used, then signal amplification is achieved, but uniformity of amplification deteriorates due to threshold voltage differences in transistors
Solution Approach 1:
The patent introduces a compensation transistor connected to the gate of the driving transistor to dynamically adjust and compensate for threshold voltage variations. By changing the electrical parameters (gate voltage) through the compensation transistor, the circuit maintains consistent amplification characteristics across different transistors despite manufacturing variations in threshold voltage.
Solution Approach 2:
The patent implements a feedback mechanism where the compensation transistor receives control signals based on the output node voltage to adjust the driving transistor's gate voltage. This feedback loop continuously corrects for threshold voltage differences, ensuring uniform amplification across the circuit.
2Adaptability or versatility
If ambient light is used to assist touchless sensing, then gesture detection is enabled, but response accuracy deteriorates under weak light conditions
Solution Approach 1:
The patent enhances the photodetector's ability to detect weak light signals by implementing signal amplification with compensation for transistor threshold voltage variations. This parameter adjustment in the amplification circuit allows accurate detection of small photoelectric signals even under weak ambient light conditions.
Solution Approach 2:
The patent uses a compensation transistor that replicates the threshold voltage characteristics of the driving transistor to create a reference for compensation. By copying the threshold voltage parameter, the circuit can accurately compensate for variations and maintain measurement precision.
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 solution enhances the uniformity of signal amplification, improving response accuracy under weak light conditions by compensating for threshold voltage differences and maintaining stable potential across nodes in the amplifying circuit.
Implementation Method 1
The working principle of photoelectric sensors is that resistance values of photodiodes change with changing optical signals, so as to realize change of photoelectric signals
Data Source
AI summary
The present application provides a signal amplifying circuit and a display device. In the signal amplifying circuit, a gate of a driving transistor of a first inverter is connected to an output terminal of a reset module, and thereby a potential of the gate of the driving transistor of the first inverter changes when an impedance of an optoelectronic device changes, so that a potential change of each node of the first inverter amplifies the signal. Besides, a first compensation transistor is connected between a second gate of the first driving transistor and a first output node, and the potential of the first output node precharges to the second gate of the first driving transistor to adjust a threshold voltage of the first driving transistor, thereby erasing the difference of the threshold voltages in different transistors, and solving the technical problem of bad uniformity of signals amplified by the inverter.