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AMOLED Pixel Circuit with Electronic Compensation for Vth and Mobility Variation in LTPS TFTs  

Woo, Doo-Hyung (School of Information, Communications & Electronic Engineering, The Catholic University of Korea)
Publication Information
Journal of the Institute of Electronics Engineers of Korea SD / v.46, no.4, 2009 , pp. 45-52 More about this Journal
Abstract
We proposed a new pixel circuit and driving method for the large-area, high-luminance AMOLED applications in this study. We designed with the low-temperature poly-silicon(LTPS) thin film transistors(TFTs) that has poor uniformity but stable characteristic. To improve the uniformity of an image, the threshold voltage($V_{TH}$) and the mobility of the TFTs can be compensated together. The proposed method overcomes the previous methods for mobility compensation, and that is profitable for large-area applications. Black data insertion was introduced to improve the characteristics for moving images. AMOLED panel can operate in two compensation mode, so the luminance degradation by mobility compensation can be released. The scan driver for controlling the pixel circuits were optimized, and the compensation mode can be controlled simply by that. Final driving signal has large timing margin, and the panel operates stably. The pixel circuit was designed for 14.1" WXGA top-emission ANGLED panel. The non-uniformity of the designed panel was estimated under 5% for the mobility compensation time of 1us.
Keywords
AMOLED; LTPS TFT; mobility compensation; compensation circuits;
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