A CMOS-compatible compact display

Abstract

Portable information devices demand displays with high resolution and high image quality that are increasingly compact and energy-efficient. Microdisplays consisting of a silicon CMOS backplane integrated with light generating or modifying devices, are being developed for direct-view and projection applications. A microdisplay architecture using silicon light emitters and image intensification suitable for a micro-projector application is developed. A standard low-voltage CMOS IC incorporating display drivers and an array of avalanche diodes produces a faint optical image, and an image intensifier efficiently amplifies the image to useful brightness. This architecture has high efficiency and the potential to achieve adequate luminance for projection applications. A proof-of-concept system with 16x32 arrays is implemented and evaluated. A high-performance silicon backplane for the above system is designed, implemented, and evaluated. The backplane is a standard CMOS die including a 360x200 pixel array with silicon light emitters, and 10b precision current-mode driver circuits. The driver circuits can support a number of emissive display technologies including silicon light emitters and organic light emitting diode (OLED).

(cont.) They employ a self-calibration technique based on the current copier circuit to minimize variation and fixed-pattern noise while reducing circuit area by a factor of five to seven compared to a conventional solution. A circuit technique to improve the retention time of dynamic analog memories is also presented. This technique allows a dynamic analog memory to retain 10b precision for 500ms at room temperature.