Charged Coupled Device

A charge-coupled device (CCD) is an analog shift register, enabling analog signals (electric charges) to be transported through successive stages (capacitors) controlled by a clock signal. Charge coupled devices can be used as a form of memory or for delaying analog, sampled signals. Today, they are most widely used for serializing parallel analog signals, namely in arrays of photoelectric light sensors. This use is so predominant that in common parlance, "CCD" is (erroneously) used as a synonym for a type of image sensor even though, strictly speaking, "CCD" refers solely to the way that the image signal is read out from the chip.
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a device that takes input light or electric charge and converts the intensity of the input into an output electronic signal. Charged coupled devices are designed as a group of pixels, where each pixel will trap electrons in proportion to the input stimuli. Each pixel may be read in sequence to determine the input stimuli level. Charged coupled devices are widely used in scientific instruments and digital cameras to capture images. Charged coupled devices are however more difficult to make than more common processes such as CMOS, although they do have better imaging performance. Due to easier fabrication, CMOS sensors are making inroads into traditional charged coupled device applications in the low-end, and CMOS sensor quality is rapidly improving as well.