Digital and Analog Hybrid (DAH) PWM Pixel Circuit Enabled by Multilevel Reference Voltage for AM μ LED Display

In this article, a digital and analog hybrid pulsewidth modulation (DAH-PWM) driven pixel circuit is proposed for active-matrix micro light-emitting diode (AM$\mu $LED) displays. The DAH mode is realized by integrating the sub-frame control scheme of digital PWM (D-PWM) into the driving architecture of analog PWM (A-PWM) using a multilevel reference voltage. It is shown that the DAH-PWM pixel circuit necessitates only half the data programming time compared to the conventional D-PWM approach. It achieves a notable reduction in pulsewidth modulation (PWM) conversion time, down to 11.2% of that in the A-PWM method. Furthermore, despite its compact 6T2C structure, the proposed circuit demonstrates a strong threshold voltage (${V}_{T}\text {)}$compensation capability. Experimental measurements confirm that the grayscale error keeps below 3.7%, even when the${V}_{T}$shifts by 2 V.