Abstract

No abstract

This work proposes a new pixel circuit for active-matrix organic light-emitting (AMOLED) smartwatch displays with a low frame rate. Within the long emission period, the leakage current of a lowtemperature polycrystalline silicon thin-film transistor (LTPS TFT) is reduced to suppress the distortion of the driving voltage at the gate node of the driving TFT. Based on the measured electrical characteristics of a fabricated p-type LTPS TFT, the HSPICE model is established to verify the feasibility of the proposed circuit. The analytical results indicate that the relative OLED current error rates are all below 4.73%, as the threshold voltage of TFT varies by ±0.5 V. Notably, the OLED current varies by only 2.94% during the emission period of 66.7 ms at a medium gray level, demonstrating the effectiveness of the leakage prevention scheme. INDEX TERMS Active-matrix organic light-emitting diode (AMOLED), low-temperature polycrystalline silicon thin-film transistors (LTPS TFTs), leakage current prevention.

This paper collates design concepts of low-power gate driver circuits, and our related work is reviewed. Many approaches to power consumption amelioration have been developed and focus on different parts of circuit structures. Recently, low-frequency clock signals are adopted to further reduce both power consumption and thin-film transistor (TFT) threshold voltage shifts (ΔV TH ).

This paper presents a new low-power gate driver circuit designed by hydrogenated amorphous silicon thin-film transistors (a-Si:H TFTs). An attempt is also made to reduce the power consumption resulting from the high-frequency pulldown structure, in which a pair of 0.25-Hz clock signals is used to implement a low-frequency and synchronously controlled pull-down scheme for recovering the threshold voltage shifts of a-Si:H TFTs under the negative gate-to-source voltage and decreasing the used TFTs. Measurement results indicate that the proposed gate driver circuit consumes 98.7 µW/stage, and the output waveforms are very stable without distortion when the proposed circuit is operated at 100°C for 840 h. Furthermore, the feasibility of the proposed gate driver circuit is demonstrated for the quad-extended-video-graphics-array resolution.Index Terms-Gate driver circuit, power consumption, quad-extended video graphics array (QXGA), threshold voltage shift.