An analog PWM pixel circuit with shaping function for low grayscale display of Micro-LEDs

This paper presents a new analog pulse width modulation (PWM) micro light-emitting diode (LED) pixel circuit with a shaping function. The rising/falling time of PWM signal generated by the proposed pixel circuit can be greatly reduced to improve the low grayscale display quality of micro-LED. Metal oxide thin film transistors with the top-gate (TG) coplanar structure are used to realize the proposed pixel circuit on the glass substrate. It is shown that the pulse width of micro-LED current can be linearly modulated by the data voltage. Furthermore, the measured rising time and falling time of the PWM signal are 15.6 mu s and 25.5 mu s, respectively, which are much smaller than that of the PWM signal in the conventional analog PWM pixel circuits.