38.2: An Accurate and Stable PWM Pixel Circuit Based on LTPO TFTs for AM‐Micro‐LED Display
Yunfei Liu, Shan Que, Zhibang Song, Jia Fu, Xin Zheng, Congwei Liao, Xinwei Wang, Lei Lü, Shengdong Zhang
Abstract
A pulse-width-modulation (PWM) pixel circuit for Micro-LED displays is proposed based on low-temperature poly-silicon and oxide (LTPO) thin-film transistors (TFTs). The pixel circuit features fast PWM transition, as the PWM falling-time is less than 20 μs thanks to the high-gain dynamic inverter. Furthermore, the proposed pixel circuit can compensate the degradation and non- uniformities of TFT characteristics of LTPO TFTs through auto- zeroing configuration of the dynamic inverter and a diode- connected threshold voltage compensation structure. The error rate of luminous time is less than 3.2% and the error rate of current is less than 1% under VTH shift of oxide TFT ±2 V or LTPS TFT ±1 V.