Pixel Driving Circuit With Capacitive Compensation for Uniform Illumination
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Solution Overview
Problem
The variation in voltage values due to parasitic capacitance causes uneven illumination and incorrect illumination under low grayscale operation in electronic circuits, particularly in display devices.
Innovation Solution
The electronic circuit incorporates a driving transistor, an emitting transistor, a reset transistor, and a capacitor to compensate for parasitic capacitance by capacitive coupling, ensuring consistent voltage delivery to the electronic element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If parasitic capacitance Cgd is present between the second terminal and control terminal of the driving transistor, then the circuit structure is simple, but voltage variation occurs causing uneven illumination
Solution Approach 1:
A compensation capacitor Cg is introduced as an intermediary element between the control terminal and second terminal of the driving transistor. This capacitor serves as a mediator to counteract the harmful effect of parasitic capacitance Cgd by providing an equal and opposite coupling effect, thereby eliminating voltage variation and achieving uniform illumination without fundamentally changing the overall circuit topology
Solution Approach 2:
The invention converts the harmful parasitic capacitance effect into a beneficial compensation mechanism. By intentionally introducing a compensation capacitor that replicates the parasitic coupling effect in reverse, the harmful voltage variation caused by Cgd is transformed into a controlled compensating signal that cancels out the unwanted effect, turning the parasitic phenomenon into a useful design feature
2Adaptability or versatility
If the power supply voltage ARVDD' is lower than the reference voltage ARVDD, then the circuit can operate under low grayscale conditions, but voltage variation through parasitic capacitance causes incorrect illumination
Solution Approach 1:
The compensation capacitor Cg creates a feedback mechanism that senses voltage changes at the second terminal and counteracts their effect on the control terminal. When the driving transistor switches states, the parasitic capacitance Cgd causes voltage variation that would lead to incorrect illumination; the compensation capacitor detects this variation and provides an opposing voltage change through capacitive coupling, forming a negative feedback loop that maintains accurate illumination control
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 capacitive coupling of the capacitor offsets the capacitive coupling of parasitic capacitance, reducing voltage variations and preventing transient currents, thereby ensuring uniform illumination across the circuit.
Implementation Method 1
The first terminal of the capacitor is electrically connected to the control terminal of the driving transistor. The second terminal of the capacitor is electrically connected to the first reset transistor and the first emitting transistor. When the electronic element is driven, the capacitive coupling of the capacitor offsets the capacitive coupling of parasitic capacitance.
Data Source
AI summary
An electronic circuit is provided. The electronic circuit includes an electronic element, a driving transistor, a first emitting transistor, a first reset transistor and a capacitor. The driving transistor is electrically connected to the electronic element. A power voltage is passed through the driving transistor to drive the electronic element. A first terminal of the first emitting transistor is electrically connected to the power voltage. A terminal of the first reset transistor receives the reset signal. A first terminal of the capacitor is electrically connected to a control terminal of the driving transistor. A second terminal of the capacitor is electrically connected to the first reset transistor and the first emitting transistor. When the electronic element is driven, a first terminal of the driving transistor and the first terminal of the first emitting transistor receive the power voltage.