A Novel Voltage-Programmed Pixel Circuit with VT-Shift Compensation for AMOLED Displays

A novel voltage-programmed pixel circuit using hydrogenated amorphous silicon (a-Si:H) thin-film transistors (TFTs) for active-matrix organic light-emitting diode (AMOLED) displays is proposed. The threshold voltage shift (Delta V-T) of the drive TFT due to electrical stress is compensated by the change of gate-to-source voltage (Delta V-GS) generated by the Delta V-T-dependent charge transfer from the drive TFT to a TFT-based Metal-Insulator-Semiconductor (MIS) capacitor. Another MIS capacitor is used to improve OLED drive currents. Measurement results verify the effectiveness and speed of the proposed pixel circuit.