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The difference between CMOS and CCD

Camera chip sensor types

The CMOS structure is relatively simple and the same as the existing large-scale integrated circuit production process, so that the production cost can be reduced. In principle, the signal of CMOS is a charge signal in points, while CCD is a current signal in units of behavior. The former is more sensitive, faster, and more power-efficient. 

It can be seen from the working principles of the two photosensitive devices that CCD (Charge Coupled Device) has the advantage of good imaging quality, but due to the complex manufacturing process, only a few manufacturers can master it, which leads to manufacturing The cost remains high, especially for large CCD, which are very expensive. At the same resolution, CMOS (Complementary Metal-Oxide Semiconductor) is cheaper than CCD, but the image quality produced by CMOS devices is lower than CCD.

The main advantage of CMOS for CCD is that it is very power-saving. Unlike CCD composed of diodes, CMOS circuits have almost no static power consumption, and only consume power when the circuit is turned on. This makes the power consumption of CMOS only about 1/3 of that of ordinary CCD. The main problem of CMOS is that it overheats due to the frequent current changes when processing fast-changing images. If the dark current is well suppressed, there is no big problem, and if it is not suppressed well, it is very easy to appear noise.

In addition, the image data scanning method of CMOS and CCD is very different. For example, if the resolution is 3 million pixels, then the CCD sensor can continuously scan 3 million charges. The scanning method is very simple. It is like passing a bucket from one person to another, and only after the last data scan is completed. Amplify the signal. Each Pixel of a CMOS sensor has an amplifier that converts electrical charges into electrical signals.

Therefore, the CMOS sensor can amplify the signal on a per Pixel basis. This method can save any invalid transmission operations, so fast data scanning can be performed with a small amount of energy consumption, and the noise is also reduced.


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