Double-Gate Gate Driving Circuit for Threshold Drift Suppression
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Solution Overview
Problem
The existing gate driving circuits in display panels face challenges due to the short-channel effect, which causes a severe negative drift in the threshold voltage of transistors, and require a large on-state current to reliably drive light-emitting elements, making it difficult to achieve a narrow frame in display devices.
Innovation Solution
A gate driving circuit is designed with a plurality of first transistors, where at least one first target transistor includes a first light-shielding layer made of a conductive material connected to the first gate metal layer, forming a double-gate structure that suppresses the negative drift of the threshold voltage and increases the on-state current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional single-gate transistor structure is used in the gate driving circuit, then the device complexity is low and manufacturing is easier, but the threshold voltage experiences severe negative drift due to the short-channel effect, and a large transistor size is required to achieve sufficient on-state current
Solution Approach 1:
The transistor gate is segmented into two separate gates (first gate and second gate), allowing independent control of each gate terminal. This segmentation enables the first gate to control the main current flow while the second gate compensates for threshold voltage drift, thereby improving reliability without requiring a complete redesign of the transistor architecture
Solution Approach 2:
The first gate and second gate are nested within the same transistor structure, with the second gate positioned adjacent to the first gate along the channel length direction. This nesting approach allows both gates to share common structural elements such as the active layer, source and drain regions, and insulating layers, thereby improving threshold voltage stability without significantly increasing device complexity
2Reliability
If the transistor size is increased to compensate for threshold voltage drift and ensure sufficient on-state current, then the reliability of light-emitting element driving is improved, but the frame width of the display device increases, making narrow frame achievement difficult
Solution Approach 1:
The invention changes the electrical parameters of the transistor by introducing a second gate that can independently modulate the channel characteristics. By adjusting the voltage applied to the second gate, the threshold voltage can be dynamically compensated, maintaining sufficient on-state current with a smaller transistor area, thereby enabling narrow frame design while ensuring reliable light-emitting element driving
3Reliability
If a double-gate structure with conductive light-shielding layer is implemented, then the on-state current increases and threshold voltage drift is suppressed, but the manufacturing process complexity and number of fabrication steps increase
Solution Approach 1:
The conductive light-shielding layer serves multiple functions simultaneously: it acts as a light-shielding barrier to prevent photogenerated carrier interference, serves as an electrical connection path between the second gate and source/drain regions, and functions as part of the transistor gate structure. This multi-functionality reduces the need for separate dedicated components and simplifies the overall manufacturing process despite the advanced transistor structure
Solution Approach 2:
The invention merges the light-shielding function with the gate structure by making the light-shielding layer conductive and electrically connecting it to the second gate. This combination eliminates the need for separate insulating light-shielding layers and additional connection structures, thereby improving transistor performance stability while keeping the manufacturing process relatively simple
Data Source
AI summary
Provided is a gate driving circuit. The gate driving circuit includes a plurality of first transistors; wherein at least one first target transistor of the plurality of first transistors includes a first light-shielding layer disposed on a side of a base substrate, the first light-shielding layer being made of a conductive material; and a first gate metal layer and a first source/drain metal layer disposed on a side of the first light-shielding layer away from the base substrate; wherein the first light-shielding layer is connected to the first gate metal layer.