CMOS VS. CCD Sensors

See The Light! CMOS VS. CCD Sensors

CMOS vs CCD — Haven't seen the light? Let's try...

CCD Sensors have been around for 25 years or so, and in the World TECHampionships of imaging technology, it is the depending champion (See World TECHampionships of Flash Memory Card). A chip designed for imaging with a track record of quality as proven by every major digital camera manufacturer. The Challenger - a lower costing chip, with on-chip processing capability and a host of new imaging applications, the CMOS sensor.

CMOS - Complementary Metal Oxide Semiconductor
CCD - Charge-Coupled Device

Both CMOS and CCD bring strengths and weaknesses into the fray. Regardless of whether any consumer will ever ask a sales clerk, or me for that matter, if that cool-looking digital camera is CMOS or CCD, understanding how these two technologies compare with each other is important to anyone who intends to buy Digital Camera or everyone who has one.

Both CMOS and CCD imagers are manufactured in a silicon foundry and the equipment used is similar. It is in the alternative manufacturing processes and device architectures that make these sensors a bit different in both capability and performance. CCD’s birth began in the 1970s and 1980s, specifically for imaging applications, where the end result was to have the best possible image quality. The technology continues to improve and is still the choice of manufacturers in applications where image quality is the primary requirement.

A CMOS chip too is made with standard silicon processes but in high-volume foundries. Peripheral electronics, such as digital logic, clock drivers, or analog-to-digital converters, can be readily integrated with the same fabrication process. It is worth mentioning that, CMOS imagers can also benefit from process and material improvements made in mainstream semiconductor technology. Therefore we can say, the best is yet to come for CMOS technology.

Further discussing the inner sanctum of CMOS and CCD tech would require me to discuss terms such as memory cell, photosites, multiplexing, X-Y matrix, photodiode, but me, not feeling so "googly" now, we will just leave it at that.

Most PC camera manufacturers in China and Taiwan have been concentrating on CMOS models because they are cheaper and easier to make. An advantage to using CMOS sensors is their system-on-chip (SoC) layout, which uses less space, therefore a more compact digital camera. By using CMOS, makers are able to produce more compact architecture and versatile designs for PC cameras-all at lower costs. In addition, CMOS sensors are already digital video-compatible, unlike CCD sensors that require separate signal processing chips or dedicated digitizing boards for the same effect. But CCD is still ruling the higher end. In addition, the power consumption of CMOS sensors is only a tenth that of CCD sensors.

The biggest opportunities for CMOS sensors lie in new product categories for which they are uniquely suited. Applications where a need for lower power usage or integration of additional circuitry on-chip or low system cost are required. These features make CMOS sensors ideal for mobile apps like those camera phones here, there and everywhere.

But the CMOS sensor have not completely dislodged the CCD as sensor king for a number reasons, primarily it performance related. Also, it is related with the simple fact the CCDs have been mass-produced for over 25 years, more R&D, through a lot of refinements and has developed over the years whereas CMOS technology has only just begun.

But make no mistake about it, CMOS imaging technology, as it is, could deliver quality images and its weaknesses are slowly disappearing. The fact that popular digital camera brands are using CMOS on their line shows the maturity of it. The CMOS technology industry is only in the early stages of optimization for digital imaging. Maybe, given developmental years, and not even 25 years, an imminent blow to the champion is in the digital horizon.