A Single Sweep Signal Enabled Analog PWM Pixel Circuit for Progressive-Emission Mode Active-Matrix Micro-LED Displays
Yuxuan Zhu, Congwei Liao, Lingxiao Qian, Shengdong Zhang
Abstract
This letter introduces an analog pulse width modulation (A-PWM) pixel circuit for progressive-emission (PE) active-matrix micro light-emitting diode (AM<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $ </tex-math></inline-formula>LED) displays, which is enabled by a single sweep signal instead of the conventional multiple sweep signals. The PE mode is implemented by double resetting the in-pixel comparator, thereby dividing one frame into two sub-frames, where each sub-frame contains one segment of the sweep signal, together forming a complete ramp waveform. The proposed pixel circuits were fabricated using amorphous indium gallium zinc oxide thin-film transistors (a-IGZO TFTs). Measurement results showed that the A-PWM pixel circuit can express gray levels in the PE mode, and the error rate is lower than 3.62% at 64 gray level even for a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V} _{\text {T}}$ </tex-math></inline-formula> shift of 2 V.