Micro Light-Emitting Diode Pixel Circuit Based on Indium-Gallium-Zinc Oxide Thin-Film Transistors Using Pulse Width Modulation

Herein, we proposed a micro light-emitting diode (mu LED) pixel circuit based on indium-gallium-zinc oxide (IGZO) thin-film transistors (TFTs). Pulse-width modulation (PWM) was utilized to overcome the wavelength shift of the mu LEDs. The proposed pixel circuit compensated for the threshold voltage (V-TH) of the driving TFTs using a source-follower structure and the variation of mu LED forward voltage (Delta V-LED). The proposed mu LED pixel circuit successfully expressed 256 gray levels using PWM. In addition, the proposed circuit exhibited a normalized luminance error rate lower than 4.8% under V-TH variation (Delta V-TH) of +/- 1.0 and Delta V-LED of +/- 0.4 V. Consequently, the proposed mu LED pixel circuit based on IGZO TFTs successfully expressed gray levels using PWM and operated stably under Delta V-TH and Delta V-LED.