Charge Coupled Device (CCD) and Complementary Metal Oxide Semiconductor (CMOS) both have image sensors that are used for capturing digital images, but it is the technologies that are different, CCD sensors are more susceptible to vertical smear from bright light sources, while CMOS sensors are susceptible to skewing, wobbling and partial exposure, they each have their own set of strengths and weaknesses that give way to various applications, neither technology is a clear winner over the other in over all image quality, but when you speak to vendors who only specialize in one of the forms of technology they will tell you that they feel otherwise. Both forms of technology have a bright future, but there is still a need for the framework to be enhanced in regards to both of the CCD and CMOS imagers for their strengths and opportunities that they are going to be able to offer.
|Description||CCD Sensor||CMOS Sensor|
|Acronym||Charged Couple Devices||Complimentary Metal Oxide Semiconductor|
|Shutter Type||Global||Rolling (why rolling shutter effect)|
|Power Efficiency||Less Efficient||More Efficient|
CCD sensors create high quality images with low noise (grain). They are more sensitive to light. However, CCD sensors consume around 100 times more power than equivalent CMOS sensors. CMOS images tend to have more noise and need more light to create images at the proper exposure. However, CMOS sensors are much more power efficient and lower temperature, as they are moving closer to CCD in quality over time.
At the chip level the costs are very similar for both the CCD and the CMOS. Early on the proponents of CMOS were claiming that the CMOS imagers were going to be a lot cheaper. They were supposed to be able to produce the same type of high-volume wafer processing lines as the mainstream login or the memory chips, but this has not been the case. The CMOS designers had to develop specialized, optimized, and lower-volume processors that are mixed-signal fabrications in order to accommodate the requirements for good imaging. It was very similar to that of the CCD designs. It has become a very slow and expensive process to be able to provide the processes at a successful lithography node that is smaller. There is an advantage to those who have a captive foundry because they are able to maintain the attention needed by the process engineers.
There are fewer components and less power that is required to operate the CMOS cameras, however, they are still going to need companion chips in order to have the optimal image quality. This process results in a higher cost and helps to reduce the advantages that are gained from lower power consumption. The CMOS devices are a lot more complex than the CCD devices, so they are going to cost a lot more to design them. The fabrication processes of the CCD tend to be a lot more mature and optimized. As a result, it is going to cost less to fabricate and design a CCD over a CMOS imager, in regards to a high-performance application. One of the most dominating influences of the device cost is the wafer size. The larger the wafer size is, the more devices it is going to be able to produce, which means the cost per device is going to be significantly reduced. The majority of the CMOS foundries are going to offer a 200mm device, whereas, the CCD foundries tend to offer a 150mm device. The majority of the captive foundries are going to use 150mm, 200mm, and 300mm for the production for the CCD and the CMOS devices.
Beyond the pricing issue, you also have to worry about the sustainability potential. CMOS was priced below their actual costs in order to win business because they were trying to pursue a high volume and commodity applications from a limited base of various businesses. For some of those businesses, the risk that they took ended up paying off and the volume that was produced was enough to maintain a margin for viability. There were some businesses that ended up having to increase their costs, but others ended up going out of business completely. Some of the venture capitalists find high-risk startups to be interesting, whereas, imager customers are going to require a long-term support and stability plan.
There have been problems with the arrival and development of the on-chip integration, but speed is one of the areas where the CMOS imagers are able to demonstrate a considerable amount of strength. Cost advantages have been difficult for everyone to realize, but they do have a relative ease of use in the output structures that are parallel. In terms of industrial applications they are going to have great potential.
The CCD and CMOS imagers are going to remain complementary to each other. It is not so much a matter of the technology, but rather the choice is going to depend on the vendor and the application that they choose to use. There is one company that is going to remain technology neutral when it comes to the two options available to them. Even though there are a lot of differences between the two imagers, it is always going to remain in the hands of the vendor to decide which product they want to offer consumers. Everyone is going to have a different opinion of which imager is going to be the best one for them, but there is really no clear and definitive answer as to what the best option is. Take the time to go through what each one has to offer and try to make the most informed decision that you can, based on what exactly it is that you are looking for.