Pulse Signal Output Circuit with Channel-Length Leakage Control
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Solution Overview
Problem
Driver circuits with transistors of the same conductivity type can experience unstable operation due to leakage currents, leading to malfunctions in pulse signal output circuits used in display devices.
Innovation Solution
A pulse signal output circuit design where the channel length of transistors is optimized to reduce leakage currents, with at least one transistor having a multi-gate structure and using oxide semiconductors to enhance stability and mobility, and the inclusion of capacitors to maintain node potentials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If transistors of the same conductivity type are used in the driver circuit, then the manufacturing process is simplified, but the operation becomes unstable due to leakage currents
Solution Approach 1:
The patent applies local quality by making the channel lengths of transistors non-uniform within the same conductivity type circuit. Specifically, transistors at different positions (e.g., odd-numbered vs even-numbered stages) have different channel lengths to compensate for position-dependent leakage currents, thereby achieving stable operation while maintaining the simplicity of using only one transistor type
Solution Approach 2:
The patent changes the channel length parameter of transistors to different values based on their position in the circuit. This parameter variation compensates for the harmful effects of leakage currents that would otherwise cause unstable operation, allowing the circuit to function reliably with transistors of the same conductivity type
2Speed
If shorter channel length transistors are used, then the field effect mobility is improved, but the leakage current increases causing unstable operation
Solution Approach 1:
The patent implements local quality by assigning different channel lengths to transistors at different circuit positions. This allows each transistor to have optimized performance characteristics for its specific location, balancing the need for high mobility with the need to minimize position-dependent leakage effects
Solution Approach 2:
The patent introduces dynamic balance by varying channel lengths to compensate for changing conditions throughout the circuit operation. The non-uniform channel length distribution dynamically adjusts the electrical characteristics to maintain stable operation across all stages
Data Source
AI summary
An object of the present invention is to provide a pulse signal output circuit capable of operating stably and a shift register including the pulse signal output circuit. In an embodiment of the pulse signal output circuit, a transistor has a source terminal or a drain terminal connected to a gate electrode of another transistor having a source terminal or a drain terminal forming an output terminal of the pulse signal output circuit, the channel length of the transistor being longer than the channel length of the other transistor. Thereby, the amount of a leakage current modifying the gate potential of the other transistor can be reduced, and a malfunction of the pulse signal output circuit can be prevented.