A Wide-Data-Range Pixel Circuit for High-Pixel-Density Mobile Displays Using Double-Gate Oxide TFTs

Abstract

For high-pixel-density mobile displays, the pixel current should be very low, which forces the driving transistor of the pixel to operate in the subthreshold region. In this region, the data voltage range becomes very narrow, making it very challenging to accommodate 10-bit data voltages. Additionally, this results in large current deviations. The proposed circuit, composed of four TFTs and two capacitors expands the data voltage range from 1.2V to 6.5V compared to the conventional pixel circuit. This improvement is achieved by controlling the bottom gate voltage of double-gate thin-film transistors (TFTs). The expansion of data voltage range also reduces the current deviation ratio from 150.9% to 71.7% when no compensation scheme is applied.