09-05-2012, 11:46 AM
CCD versus CMOS-has CCD imaging come to an end?
ABSTRACT
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 weakness of CMOS imagers, namely with respect to noise and sensitivity. Today “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.
CCD: The first digital cameras used CCD (Charged Coupling Devices) to turn images from analog light signals into digital pixels. They're made through a special manufacturing process that allows the conversion to take place in the chip without distortion. This creates high quality sensors that produce excellent images. But, because they require special manufacturing, they are more expensive than their newer CMOS counter parts.
CMOS: (Complementary Metal Oxide Semiconductor) chips use transistors at each pixel to move the charge through traditional wires. This offers flexibility because each pixel is treated individually. Traditional manufacturing processes are used to make CMOS. It's the same as creating microchips. Because they're easier to produce, CMOS sensors are cheaper than CCD sensors. Because CMOS technology came after CCD sensors and are cheaper to manufacture, CMOS sensors are the reason that digital cameras have dropped in price.