A Charge-Pump-Based Current Feedback Method for AMOLED Displays

This work presents a new external driving scheme that uses the current feedback method with a 3T1C pixel circuit. The proposed circuit provides a stable OLED driving current by compensating for the threshold voltage shift of amorphous-silicon thin-film transistors (a-Si TFTs). For fabricated a-Si TFTs and the 0.35 μm CMOS process associated with the proposed driving scheme, measurements reveal that the normalized OLED current degradation is less than 5% after 60 hours of operation at 60°C. Moreover, for a data line load of 1.69 K Ω/110 pF, the relative error rates between data currents and OLED currents are less than 4% within a settling time of 19 μs.