CCD versus CMOS – has CCD imaging come to an end ?

CMOS image sensors are today challenging the existing Charge Coupled Devices (CCD) in several application fields. Improved architecture and processes have to a large extent overcome early weaknesses of CMOS imagers, namely with respect to noise and sensitivity. Todays " Active Pixel Sensors" are typically based on sub-micron technologies that have been optimized for optical sensing and can rival CCD in most aspects. In addition CMOS imagers offer significant advantages in terms of low power, low voltage and monolithic integration, allowing for example the manufacture of miniaturized single-chip digital cameras. The integration of added functionality on the chip or even at the pixel level also opens up completely new opportunities. This paper gives a short review of the advantages and weaknesses of both CMOS and CCD technologies for imaging applications.