Gate Driving Circuit Back-Bias Compensation for Display Leakage
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Solution Overview
Problem
The reliability of gate driving circuits in display devices is compromised due to changes in transistor driving characteristics, leading to current leakage and poor image display quality.
Innovation Solution
A gate driving circuit design that includes stages with specific transistor configurations, such as diode-connected control transistors, back-biased transistors, and capacitors, along with inverters and holding units, to compensate for threshold voltage changes and improve reliability and image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional transistor configurations are used in gate driving circuits, then the circuit structure is simple, but transistor driving characteristics change leading to current leakage and poor reliability
Solution Approach 1:
The gate driving circuit is divided into multiple stages, with each stage independently compensating for threshold voltage changes in its transistors. This segmentation allows the complexity to be distributed and managed at the stage level while achieving overall high reliability through cumulative compensation effects across all stages.
Solution Approach 2:
The invention changes the electrical parameters of transistors by applying back-bias voltages to adjust threshold voltages dynamically. This parameter change compensates for transistor characteristic drift and ensures stable operation, improving reliability without requiring complete redesign of the circuit topology.
2Manufacturing precision
If threshold voltage compensation is implemented, then current leakage is reduced and image quality improves, but the circuit complexity increases
Solution Approach 1:
The compensation mechanism performs preliminary adjustment of transistor threshold voltages before the transistors are fully activated in the main signal path. By pre-compensating for expected threshold voltage changes, the circuit maintains precise control and high image quality without adding complexity to the critical signal transmission path.
Solution Approach 2:
Back-bias voltages serve as intermediary signals that mediate between the control logic and the main signal transistors. These intermediary voltage adjustments indirectly control transistor characteristics, achieving precise threshold voltage compensation while keeping the main signal path simple and clean.
Data Source
AI summary
A stage of a gate driving circuit includes: a first control transistor diode-connected between a first input end of the stage and a first node, biased by a first input signal, and back-biased by a second input signal; a second control transistor including a control end which receives a third input signal, a first end connected to the first node, and a second end connected to a first voltage, and back-biased by a fourth input signal; a first output transistor including a control end connected to the first node, a first end connected to a clock input end of the stage, and a second end connected to a first output end of the stage; and a capacitor connected between the control and second ends of the first output transistor. The second input signal and the fourth input signal have enable levels during different periods.