What is the Difference between CCD and CMOS Image Sensors?

by techavvy

The term image sensor implies a sensor technology used to communicate and identify all the information needed to create an image.

To reflect on the topic what is the difference between CCD and CMOS image sensors, let us take a deep insight into the definition of image sensor at first.

Image Sensor

The term image sensor implies a sensor technology used to communicate and identify all the information needed to create an image. This entails – conversion of variable attenuation of light reflected as signals into smaller bursts for conveying that information. These waves are classified as

Light waves Electromagnetic radiation

Until the discovery of modern day sensor technologies such as CMOS, CCD and NMOS, analog devices ruled the imaging industry. Notwithstanding, these imaging sensors form the basic foundation of both digital as well as analog electronic devices such as

Night vision equipment Medical imaging equipment Digital cameras Thermal imaging devices camera modules

Now we are in a better position to provide a rational comparison on the topic what is the difference between CCD and CMOS image sensors.

CCD Sensor

The CCD image sensor is a charged coupled device that transports the electric charge accumulated across the chip by limited number of output nodes. In this sensor type, all the pixels are devoted to capture light for ensuring high output uniformity. Later, an analog to digital converter converts each pixel value into a digital number. A special manufacturing process in a CCD structure guides this conversion process for resultant high image quality and high light sensitivity.

CMOS Sensor

Unlike CCDs, CMOS or complementary metal oxide semiconductor represents particular digital circuitry design and refers to a series of processes implementing circuitry on integrated chips. Not only that- integrated chips are also used in microprocessors, digital logic circuits, static RAMs, data converters, highly integrated transceivers, image sensors and microcontrollers. These active pixel sensors use an electronic chip for digital processing of signals. Herein, each pixel bears its own amplifier for performing charge to voltage conversions- reducing overall area for light capture. To overcome this challenge, back side illuminated structures are embedded in some CMOS devices to enable more photons hitting the photodiode.

All in all, what is the difference between CCD and CMOS image sensors can be explained in terms of basic difference in architecture of both sensor technologies rendering their individual strengths and weaknesses.

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