Novel design of auto-compensation for TFT VTH and high-speed driving in active-matrix OLED displays

This work presents a new pixel circuit composed of six low-temperature polycrystalline-silicon (LTPS) thin-film transistors (TFTs) and two capacitors for active-matrix organic light-emitting diode (AMOLED) displays. New auto-compensation method is developed by cancelling the reference voltage which is required in general compensation circuits, thus improving the aperture ratio of pixel. By adopting the parallel addressing, the problem of long compensation time goes insignificant and driving speed of the proposed circuits can be as high as the conventional 2T circuit. TFTs and OLED are fabricated to establish models for HSPICE simulation. The current errors caused by VTH variations of TFTs are below 2% through the whole data range in ultra high-definition (UHD) displays.