3T0.5C Compensating pixel circuit with all p-type LTPS-TFTs for AMOLED displays

• Published in: Displays 2018-07, Vol.53, p.8-13
• Main Authors: Fan, Ching-Lin, Chen, Chun-Yuan, Tseng, Fan-Ping, Yang, Chuang-Cheng, Chien, Kuo-En, Hsiao, Yu-Hao
• Format: Article
• Language: English
• Subjects: Active-matrix light emitting diode (AMOLED); Low-temperature polycrystalline-silicon thin-film transistor (LTPS-TFT); Pixel circuit; Simultaneous emission
• ISSN: 0141-9382; 1872-7387
• DOI: 10.1016/j.displa.2018.04.001

•We proposed a novel pixel circuit with LTPS-TFTs for driving AMOLED displays.•The equivalent circuit is 3T0.5C in each layout area.•The pixel circuit can compensate the threshold voltage (VTH) deviation of the driving TFT and ameliorate the OLED’s lifetime.•The simulation results show the average error rate of the driving current was 1.8% when the driving TFT VTH deviated by ±0.33 V. A novel pixel circuit with low-temperature polycrystalline-silicon thin-film transistors (LTPS-TFTs) for driving active-matrix organic light-emitting diode (AMOLED) displays is proposed. The pixel circuit is built on two adjacent pixels with six p-type LTPS-TFTs and a capacitor, and thus the equivalent circuit is 3T0.5C in each layout area, which has a superior aperture ratio. The pixel circuit can compensate for the threshold voltage (VTH) deviation of the driving TFT and provide a reverse bias on the OLED to ameliorate the OLED’s lifetime. The simulation results show that the pixel circuit can provide a stable driving current to AMOLED displays and the average error rate of the driving current was 1.8% when the driving TFT threshold voltage deviated by ±0.33 V. Therefore, the proposed pixel circuit with a superior aperture ratio can show high immunity to the driving TFT threshold voltage deviation and significantly improve the uniformity of brightness of AMOLED displays.