Fast Voltage-Programmed Pixel Architecture for AMOLED Displays

We present a fast voltage programming scheme for active-matrix organic light-emitting diode (AMOLED) displays using amorphous silicon (a-Si) thin-film transistor (TFT) backplane technology. The proposed scheme uses on-pixel measurement of the threshold voltage (
V

_th
) of the drive TFT. In contrast to the conventional voltage driving,
V

_th
is not measured by discharging a capacitor through a diode-connected TFT. Thus, the accuracy-speed tradeoff does not limit the performance of the new driving scheme. A 4-TFT 2-capacitor pixel circuit is implemented based on the new driving scheme, and its performance is verified by circuit-level simulations using AIM-SPICE. Simulation results show that for a programming time of 33 ¿s , less than 2.5% change in the OLED current can be achieved for a 5-V shift in the threshold voltage of the drive TFT.