Gate Driver Double-Gate Transistor Leakage Current Reduction
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Solution Overview
Problem
In display devices, particularly organic light emitting display devices, the addition of transistors to improve discharge characteristics leads to increased bezel size, leakage current, and power consumption due to the operation of transistors at Vgs=0V, resulting in output degradation of gate signals.
Innovation Solution
A gate driver is designed with a double-gate transistor structure, where a negative bias is applied to the back gate electrode when transistors are turned off, reducing leakage current and eliminating the need for additional transistors, thereby minimizing power consumption and bezel size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional transistors are added to improve discharge characteristics, then discharge performance is improved, but leakage current increases and power consumption increases
Solution Approach 1:
The patent applies parameter changes by utilizing the back gate voltage to dynamically control the threshold voltage of transistors. By adjusting the back gate voltage, the transistor threshold voltage is modified to prevent leakage current during the off-state while maintaining proper discharge characteristics during operation, thus resolving the contradiction between discharge performance and leakage current.
Solution Approach 2:
The patent introduces another dimension of control by adding the back gate voltage control mechanism to the traditional gate-controlled transistor operation. This additional control dimension allows independent optimization of both on-state discharge characteristics and off-state leakage current by manipulating the back gate voltage separately from the gate voltage.
2Reliability
If additional transistors are added to improve discharge characteristics, then discharge performance is improved, but bezel size increases
Solution Approach 1:
The patent applies universality by making the back gate electrode serve multiple functions: it acts as both a structural component of the transistor and a control element for adjusting threshold voltage. This multi-functionality allows the existing transistor structure to achieve improved discharge characteristics without adding separate dedicated transistors, thereby avoiding bezel size increase.
Solution Approach 2:
By changing the operational parameters of existing transistors through back gate voltage control, the patent achieves improved discharge characteristics without increasing the number of transistors or expanding the bezel area, thus resolving the contradiction between discharge performance and bezel size.
3Ease of operation
If transistors operate at Vgs=0V in off section, then transistor is turned off, but leakage current is generated
Solution Approach 1:
The patent changes the parameter control approach by introducing back gate voltage as an additional control variable. Even when the gate-source voltage is 0V (off-state), the back gate voltage can be adjusted to modify the threshold voltage, thereby suppressing leakage current while maintaining the simple Vgs=0V off-state switching operation.
Solution Approach 2:
The patent applies preliminary anti-action by using the back gate voltage to preemptively counteract the leakage current tendency before it becomes significant. By controlling the back gate voltage, the threshold voltage is adjusted in advance to prevent leakage current generation during the off-state, thus resolving the contradiction between easy switching and leakage current.
Data Source
AI summary
A gate driver includes signal transmission units cascade-connected via a carry line to which a carry signal is applied from a previous signal transmission unit. An nth signal transmission unit includes: a first circuit including a first Q logic generator to receive the carry signal from the previous signal transmission unit to charge a first control node, and a second Q logic generator to discharge the first control node; a second circuit to discharge a second control node according to a first control node voltage; and an output to output the carry signal and a gate signal based on potentials of the first and second control nodes. The second Q logic generator includes: a second-1 transistor and a second-2 transistor each respectively having a first electrode, a gate electrode, a back gate electrode, and a second electrode.