CMOS-based microdisplay with calibrated backplane

Abstract

A two-stage microdisplay architecture using silicon light emitters and image intensification is presented. A backplane IC implemented in standard 0.18-/spl mu/m CMOS technology incorporating display drivers and an array of avalanche diodes produces a faint optical image, and an image intensifier efficiently amplifies the image to useful luminance levels. This architecture can achieve adequate luminance for projection applications and high energy efficiency. The integrated backplane includes a 360 /spl times/ 200 pixel array with silicon light emitters and 10b precision current-mode driver circuits. The driver circuits can support both silicon light emitters and organic LED (OLED). 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 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 current copier to retain 10b precision for 500 ms at room temperature.