Very High Brightness, High Resolution CMOS Driving Circuit for Microdisplay in Augmented Reality

Abstract

In augmented reality applications, high brightness at high resolution is crucial to guarantee a good user experience. Explorations on efficient light sources have already been undertaken, and GaN μLEDs tend to be a good candidate. Nevertheless, micro-display driving circuits usually do not provide sufficient luminance level to offer good contrast against ambient light. We report the design and fabrication of a GaN LED microdisplay driving circuit, designed in a 0.18μm CMOS process with a 1640×1033 resolution. Each LED is controlled individually by a CMOS pixel with a 9.5μm pitch. The monochrome green microdisplay enables more than the WSXGA resolution and can reach 3.8MCd/m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> for a fully ON micro-LED array. This driving circuit enables, to our knowledge, the highest brightness for such a pixel pitch and resolution.