What is the difference between a CCD matrix and a CMOS matrix?
What is the difference between a CCD matrix and a CMOS matrix?
By that time, it had become obvious that CCD provided better performance when shooting dynamic and small objects, so it was proposed to use it to build systems that required high image quality: digital photo and video cameras, medical equipment, etc. CMOS was allocated a niche of devices for which the final cost was critical — inexpensive cameras, household and office equipment and toys.
The experience gained in manufacturing over the years of CMOS development has allowed each new generation of these sensors to significantly reduce fixed and random noise that affects image quality. Another weak point of CMOS is distortions that appear when capturing a dynamic image due to the low sensitivity of the sensor. In modern devices, they can be avoided, and image capture without any particular artifacts is possible at a speed of 15-30 frames per second, and 0.3-megapixel CMOS sensors have already been virtually freed from this problem.
However, victory in the competition between technologies most likely lies in reducing the pixel area. For success in the 1-megapixel market with a 1/4-inch diagonal, the pixel area should be no more than 3 μm2. Despite all the efforts of CMOS manufacturers, they are not yet able to meet such requirements, therefore, as experts believe, at least in the near future, CCD will dominate in this niche.
Many major component manufacturers produce both CMOS sensors and CCD matrices. For example, Sharp, the world's largest supplier of image capture modules (both CCD and CMOS), considers 2003 to be the heyday of CCD technology.
The advantages of CCD matrices include:
1. Low noise level.
2. High pixel fill factor (around 100%).
3. High efficiency (the ratio of the number of registered photons to their total number that hit the photosensitive area of the matrix, for CCD — 95%).
4. High dynamic range (sensitivity).
The disadvantages of CCD matrices include:
1. Complex signal reading principle, and therefore technology.
2. High power consumption (up to 2-5W).
3. More expensive to produce.
Advantages of CMOS matrices:
1. High speed (up to 500 frames/s).
2. Low power consumption (almost 100 times compared to CCD).
3. Cheaper and easier to produce.
4. The technology is promising (in principle, it is easy to implement all the necessary additional circuits on the same crystal: analog-to-digital converters, processor, memory, thus obtaining a complete digital camera on a single crystal. By the way, Samsung Electronics and Mitsubishi Electric have been working together to create such a device since 2002).
The disadvantages of CMOS matrices include
1. Low pixel fill factor, which reduces sensitivity (effective pixel surface ~75%, the rest is occupied by transistors).
2. High noise level (it is caused by so-called tempo currents — even in the absence of lighting, a fairly significant current flows through the photodiode), the fight against which complicates and increases the cost of the technology.
3. Low dynamic range.