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 (
${V}_{\text {TH}}{)}$
of the driving TFTs using a source-follower structure and the variation of
$\mu $
LED forward voltage (
$\Delta {V}_{\text {LED}}{)}$
. 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
${V}_{\text {TH}}$
variation (
$\Delta {V}_{\text {TH}}{)}$
of ±1.0 and
$\Delta {V}_{\text {LED}}$
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
$\Delta {V}_{\text {TH}}$
and
$\Delta {V}_{\text {LED}}$
.