A novel voltage-programmed pixel circuit with VT-shift compensation for AMOLED displays

摘要

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 (ΔVT) of the drive TFT due to electrical stress is compensated by the change of gate-to-source voltage (ΔVGS) generated by the ΔVT-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.