A Hybrid AMOLED Driver IC for Real-Time TFT Nonuniformity Compensation

• Published in: IEEE journal of solid-state circuits 2016-04, Vol.51 (4), p.966-978
• Main Authors: Jun-Suk Bang, Kim, Hyun-Sik, Kim, Ki-Duk, Oh-Jo, Kwon, Choong-Sun, Shin, Lee, Joohyung, Cho, Gyu-Hyeong
• Format: Article
• Language: English
• Subjects: Active matrix organic light emitting diode (AMOLED); Active matrix organic light emitting diodes; Apertures; circuit-reused current-mode ADC; data driver; hybrid driver; Integrated circuits; offset-compensated integrating comparator (OCIC); OLED degradation; Real-time systems; Sensors; Thin film transistors; thin-film transistor (TFT); threshold voltage shift
• ISSN: 0018-9200; 1558-173X
• DOI: 10.1109/JSSC.2015.2504416

An active matrix organic light emitting diode (AMOLED) display driver IC, enabling real-time thin-film transistor (TFT) nonuniformity compensation, is presented with a hybrid driving method to satisfy fast driving speed, high TFT current accuracy, and a high aperture ratio. The proposed hybrid column-driver IC drives a mobile UHD (3840 × 2160) AMOLED panel, with one horizontal time of 7.7 μs at a scan frequency of 60 Hz, simultaneously senses the TFT current for back-end TFT variation compensation. Due to external compensation, a simple 3T1C pixel circuit is employed in each pixel. Accurate current sensing and high panel noise immunity is guaranteed by a proposed current-sensing circuit. By reusing the hybrid column-driver circuitries, the driver embodies an 8 bit current-mode ADC to measure OLED V -I transfer characteristic for OLED luminance-degradation compensation. Measurement results show that the hybrid driving method reduces the maximum current error between two emulated TFTs with a 60 mV threshold voltage difference under 1 gray-level error of 0.94 gray level (37 nA) in 8 bit gray scales from 12.82 gray level (501 nA). The circuit-reused current-mode ADC achieves 0.56 LSB DNL and 0.75 LSB INL.