A Highly Reliable, Stacked-Capacitor, Voltage-Programmed Pixel Circuit Using a-IGZO TFTs for AMOLED Displays

This paper proposes a stacked-capacitor pixel circuit for flexible AMOLED (Active Matrix-Organic Light Emitting Diode) displays based on the a-IGZO (Amorphous-Indium Gallium Zinc Oxide) TFT (Thin Film Transistor). A calibrated HSPICE level-61 a-IGZO TFT model is used for CAD simulations. The proposed design compensates for V[Formula: see text] shifts in the TFT by employing a stacked capacitor configuration for threshold voltage detection. The simulated results show a percentage error in the OLED current of less than 0.04% for a maximum tensile and compressive strain of 0.3%. The circuit can suppress the error in OLED current to 1.83% for a V[Formula: see text] shift in the range of 0 V to 2.1 V, from the nominal 0.7 V, with an input data voltage of 15 V. Therefore, the proposed pixel circuit topology proves to be a highly reliable pixel architecture which can be effectively used in AMOLED displays.