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An Active-Matrix Organic Light-Emitting Diode Pixel Circuit Featuring Mobility Compensation for Portable Applications
Ching-Lin Fan1,2, Wei-Yu Lin1, Shih-Yang Liu2
1Graduate Institute of Electro-Optical Engineering, National Taiwan University of Science and Technology, No. 43, Sec. 4, Keelung Rd., Da'an Dist., Taipei City 106, Taiwan.
Micromachines
|September 28, 2023
Summary
A new 6T1C pixel circuit using low-temperature polycrystalline oxide (LTPO) technology enhances portable active-matrix organic light-emitting diode (AMOLED) displays. This design offers low-voltage driving and compensates for degradation, improving display performance.
Area of Science:
- Electrical Engineering
- Materials Science
- Display Technology
Background:
- Portable active-matrix organic light-emitting diode (AMOLED) displays require advanced pixel circuitry for high resolution and performance.
- Existing pixel circuits face challenges with low-voltage driving, IR-drop, and degradation of organic light-emitting diodes (OLEDs).
Purpose of the Study:
- To propose and evaluate a novel 6T1C pixel circuit for portable AMOLED displays.
- To achieve low-voltage driving with compensation for threshold voltage and mobility variations.
- To ensure immunity to IR-drop and OLED degradation for enhanced display reliability.
Main Methods:
- Implementation of a 6T1C (six transistors, one capacitor) pixel circuit architecture.
- Utilizing low-temperature polycrystalline oxide (LTPO) technology.
- Employing a single storage capacitor and signal sharing switch-control design.
- Incorporating negative feedback systems for threshold voltage and mobility compensation.
Main Results:
- The proposed circuit effectively compensates for threshold voltage variations up to ±0.33 V in driving thin-film transistors.
- Maximum OLED current shift due to variations is limited to 4.25%.
- OLED current variation across all gray levels is minimal (1.05%) even with ±30% mobility variations.
Conclusions:
- The novel 6T1C pixel circuit demonstrates robust performance for high-end portable AMOLED applications.
- The circuit's compensation mechanisms ensure stable and reliable display operation.
- This LTPO-based design is a promising solution for future high-resolution, high-PPI portable displays.
