CCD and CMOS matrices. Comparison of matrices in video cameras and cameras (CMOS, CCD)

The image sensor is the most important element of any video camera. Today, almost all cameras use CCD or CMOS image sensors. Both types of sensor perform the task of converting the image built on the sensor by the lens into an electrical signal. However, the question of which sensor is better still remains open.

N.I. Chura
Technical advisor
Microvideo Group LLC

CCD is an analog sensor, despite the discreteness of the light-sensitive structure. When light hits the matrix, each pixel accumulates a charge or packet of electrons, which is converted, when read out by a load, into a video signal voltage proportional to the illumination of the pixels. The minimum number of intermediate transitions of this charge and the absence of active devices ensure high identity of the CCD sensitive elements.

The CMOS matrix is ​​a digital device with active pixel sensors. Each pixel has its own amplifier, which converts the charge of the sensitive element into voltage. This makes it possible to control each pixel almost individually.

Evolution of CCD

Since the invention of CCD by Bell Laboratories (or Bell Labs) in 1969, image sensor sizes have continually decreased. At the same time, the number of sensitive elements increased. This naturally led to a decrease in the size of a single sensitive element (pixel), and, accordingly, its sensitivity. For example, since 1987 these sizes have decreased by 100 times. But thanks to new technologies, the sensitivity of one element (and therefore the entire matrix) has even increased.

What allowed us to dominate
From the very beginning, CCDs became the dominant sensors because they provided better image quality, less noise, higher sensitivity, and greater pixel uniformity. The main efforts to improve the technology were aimed at improving the performance of CCD.

How sensitivity grows
Compared to the popular standard definition Sony HAD matrix (500x582) of the late 1990s. (ICX055) the sensitivity of models with more advanced Super HAD technology increased almost 3 times (ICX405) and Ex-view HAD - 4 times (ICX255). And for black and white and color versions.

For high-resolution matrices (752x582), the successes are somewhat less impressive, but if we compare Super HAD color image models with the most modern Ex-view HAD II and Super HAD II technologies, the increase in sensitivity will be 2.5 and 2.4 times, respectively. And this despite a reduction in pixel sizes by almost 30%, since we are talking about matrices of the most modern 960H format with an increased number of pixels to 976x582 for the PAL standard. To process such a signal, Sony offers a range of Effio signal processors.

Added IR component
One of the effective methods for increasing integral sensitivity is to expand the spectral characteristics of sensitivity into the infrared region. This is especially true for the Ex-view matrix. The addition of the IR component somewhat distorts the transfer of the relative brightness of colors, but for the black and white version this is not critical. The only problem arises with color rendering in day/night cameras with constant IR sensitivity, that is, without a mechanical IR filter.

The development of this technology in the Ex-view HAD II models (ICX658AKA) in comparison with the previous version (ICX258AK) provides an increase in integral sensitivity of only 0.8 dB (from 1100 to 1200 mV) with a simultaneous increase in sensitivity at a wavelength of 950 nm by 4. 5 dB. In Fig. 1 shows the characteristics of the spectral sensitivity of these matrices, and Fig. 2 – the ratio of their integral sensitivity.

Optical Innovation
Another method for increasing CCD sensitivity is to increase the efficiency of pixel microlenses, the photosensitive area, and optimize color filters. In Fig. Figure 3 shows the structure of the Super HAD and Super HAD II matrices, showing the increase in the lens area and photosensitive area of ​​the latest modification.

Additionally, Super HAD II matrices have significantly increased the transmission of light filters and their resistance to fading. In addition, transmission in the short-wavelength region of the spectrum (blue) has been expanded, which has improved color rendering and white balance.

In Fig. Figure 4 shows the spectral sensitivity characteristics of the Sony 1/3" Super HAD (ICX229AK) and Super HAD II (ICX649AKA) matrices.

CCD: Unique Sensitivity

Taken together, the above measures have achieved significant results in improving the performance of CCD.

It is not possible to compare the characteristics of modern models with earlier versions, since color matrices for widespread use, even of standard high resolution, were not produced at that time. In turn, standard definition black-and-white matrices using the latest Ex-view HAD II and Super HAD II technologies are not currently produced.

In any case, in terms of sensitivity, CCDs are still an unattainable benchmark for CMOS, so they are still widely used with the exception of megapixel variants, which are very expensive and are used mainly for special tasks.

CMOS: advantages and disadvantages

CMOS sensors were invented in the late 1970s, but their production did not begin until the 1990s due to technological problems. And their main advantages and disadvantages immediately emerged, which remain relevant today.

Advantages include greater sensor integration and cost-effectiveness, wider dynamic range, ease of production and lower cost, especially for megapixel variants.

On the other hand, CMOS sensors have lower sensitivity due, other things being equal, to large losses in RGB filters and a smaller usable area of ​​the photosensitive element. As a result of the many transition elements, including amplifiers in the path of each pixel, ensuring uniformity of the parameters of all sensitive elements is much more difficult compared to CCD. But improvements in technology have brought CMOS sensitivity closer to the best CCD designs, especially in megapixel versions.

Early proponents of CMOS argued that these structures would be much cheaper because they could be manufactured on the same hardware and technologies as memory and logic chips. In many ways, this assumption was confirmed, but not completely, since the improvement of technology led to a production process almost identical in complexity to that for CCD.

With the expansion of the circle of consumers beyond standard television, the resolution of matrices began to continuously increase. These are household video cameras, electronic cameras and cameras built into communication devices. By the way, for mobile devices the issue of efficiency is quite important, and here the CMOS sensor has no competitors. For example, since the mid-1990s. The resolution of the matrices has increased annually by 1–2 million elements and now reaches 10–12 Mpcs. Moreover, the demand for CMOS sensors has become dominant and today exceeds 100 million units.

CMOS: improved sensitivity

The first samples of surveillance cameras from the late 1990s – early 2000s with CMOS matrices had a resolution of 352x288 pixels and a sensitivity even for black and white of about 1 lux. Color versions of standard resolution differed in sensitivity of about 7–10 lux.

What do suppliers offer?
Currently, the sensitivity of CMOS matrices has certainly increased, but for typical color image options it does not exceed values ​​of the order of several lux at reasonable values ​​of the lens F number (1.2–1.4). This is confirmed by the technical specifications of IP video surveillance brands that use progressive scan CMOS matrices. Those manufacturers who claim sensitivity of about tenths of a lux usually specify that these are data for a lower frame rate, accumulation mode, or at least an enabled and sufficiently deep AGC (AGC). Moreover, for some IP camera manufacturers, the maximum AGC reaches a mind-boggling value of –120 dB (1 million times). One can hope that the sensitivity for this case in the minds of the manufacturers presupposes a decent signal-to-noise ratio, allowing one to observe more than just “snow” on the screen.

Innovation improves video quality
In an effort to improve the performance of CMOS matrices, Sony has proposed a number of new technologies that provide practical comparison of CMOS matrices with CCD in terms of sensitivity, signal-to-noise ratio in megapixel versions.

The new technology for the production of Exmor matrices is based on changing the direction of incidence of the light flux on the matrix. In a typical architecture, light strikes the front surface of the silicon wafer through and past the array circuit conductors. Light is scattered and blocked by these elements. In the new modification, light enters the back side of the silicon wafer. This led to a significant increase in sensitivity and reduction in noise of the CMOS matrix. In Fig. Figure 5 explains the differences between the structures of the standard matrix and the Exmor matrix, shown in section.

Photo 1 shows images of the test object taken at an illumination of 100 lux (F4.0 and 1/30 s) with a camera with CCD (front illumination) and CMOS Exmor, having the same format and resolution of 10 megapixels. Obviously, a CMOS camera image is at least as good as a CCD camera image.

Another way to improve the sensitivity of CMOS sensors is to move away from the rectangular pixel arrangement with line-shifted red and blue elements. In this case, in the construction of one resolution element, two green pixels are used - blue and red from different rows. Instead, a diagonal arrangement of elements is proposed, using six adjacent green elements to construct one resolution element. This technology is called ClearVid CMOS. A more powerful image signal processor is assumed for processing. The difference in the structures of the arrangement of colored elements is illustrated in Fig. 6.

Information is read by a high-speed parallel analog-to-digital converter. At the same time, the progressive scan frame rate can reach 180 and even 240 fps. When recording information in parallel, the diagonal frame shift common to CMOS cameras with sequential exposure and signal reading is eliminated, the so-called Rolling Shutter effect - when the characteristic blur of fast moving objects is completely absent.

Photo 2 shows images of a rotating fan taken with a CMOS camera at frame rates of 45 and 180 fps.

Full competition

We cited Sony technologies as examples. Naturally, CMOS matrices, like CCDs, are also produced by other companies, although not on such a scale and not so well known. In any case, everyone, one way or another, follows approximately the same path and uses similar technical solutions.

In particular, the well-known technology of Panasonic Live-MOS matrices also significantly improves the characteristics of CMOS matrices and, naturally, by similar methods. Panasonic matrices have reduced the distance from the photodiode to the microlens. The transmission of signals from the surface of the photodiode is simplified. The number of control signals has been reduced from 3 (standard CMOS) to 2 (as in CCD), which has increased the photosensitive area of ​​the pixel. A low noise photodiode amplifier is used. A thinner sensor layer structure is used. Reduced supply voltage reduces noise and heat of the matrix.

It can be stated that megapixel CMOS matrices can already successfully compete with CCD not only in price, but also in such problematic characteristics for this technology as sensitivity and noise level. However, in traditional CCTV television formats, CCD matrices remain uncompetitive.

CMOS matrix

CMOS matrices use insulated gate field effect transistors with channels of different conductivity.

Story

At the end of the 1960s. Many researchers have noted that CMOS structures are sensitive to light. However, charge-coupled devices provided such higher photosensitivity and image quality that matrices based on CMOS technology did not receive any noticeable development.

In the early 1990s, the characteristics of CMOS sensors, as well as manufacturing technology, were significantly improved. Advances in submicron photolithography have enabled thinner connections to be used in CMOS sensors. This led to an increase in photosensitivity due to a larger percentage of the irradiated matrix area.

A revolution in CMOS sensor technology occurred when NASA's Jet Propulsion Laboratory (JPL) successfully implemented Active Pixel Sensors (APS) - active pixel sensors . Theoretical studies were carried out several decades ago, but the practical use of the active sensor was delayed until 1993. APS adds a transistor readout amplifier to each pixel, making it possible to convert charge into voltage directly at the pixel. This also provided random access to photodetectors similar to RAM implemented in microcircuits.

As a result, by 2008, CMOS had become practically an alternative to CCD.

Last year, at the MWC forum in Barcelona, ​​Samsung demonstrated a new type of CMOS sensors that are aimed at use in smartphones.

Principle of operation

• Before shooting, a reset signal is given
• During exposure, charge is accumulated by the photodiode
• During the reading process, the voltage value on the capacitor is sampled

Advantages

• The main advantage of CMOS technology is low power consumption in a static state. This makes it possible to use such matrices as part of non-volatile devices, for example, in motion sensors and surveillance systems that spend most of the time in “sleep” or “waiting for an event” mode.
• An important advantage of the CMOS matrix is ​​the unity of the technology with other digital elements of the equipment. This leads to the possibility of combining analog, digital and processing parts on one chip (CMOS technology, being primarily a processor technology, implies not only the “capture” of light, but also the process of converting, processing, cleaning signals not only actually captured, but and third-party REA components), which served as the basis for the miniaturization of cameras for a wide variety of equipment and reducing their cost due to the elimination of additional processor chips.
• Using a random access mechanism, selected groups of pixels can be read. This operation is called windowing readout. Cropping allows you to reduce the size of the captured image and potentially increase readout speed compared to CCD sensors, since in the latter all information must be downloaded for further processing. It becomes possible to use the same matrix in fundamentally different modes. In particular, by quickly reading only a small part of the pixels, it is possible to provide a high-quality live image viewing mode on the screen built into the device with a relatively small number of pixels. You can scan only part of the frame and apply it to display on the entire screen. Thus, you will be able to achieve high-quality manual focusing. It is possible to conduct high-speed reportage shooting with a smaller frame size and resolution.
• In addition to the amplifier inside the pixel, amplification circuits can be placed anywhere along the signal path. This allows you to create amplification stages and increase sensitivity in poor lighting conditions. The ability to change the gain for each color improves white balancing in particular.
• Cheap production compared to CCD matrices, especially with large matrix sizes.

Flaws

• The cell's photodiode occupies significantly less matrix element area compared to a full-frame transfer CCD. Therefore, early CMOS sensors had significantly lower light sensitivity than CCDs. But in 2007, Sony launched a new line of video and photo cameras with a new generation of CMOS matrices with Exmor technology, which was previously used only for CMOS matrices in specific optical devices such as electronic telescopes. In these matrices, the electronic “strapping” of the pixel, which prevents photons from reaching the light-sensitive element, was moved from the upper to the lower layer of the matrix, which made it possible to increase both the physical size of the pixel with the same geometric dimensions of the matrix, and the accessibility of the elements to light, which, accordingly, increased the photosensitivity of each pixel and the matrix as a whole. For the first time, CMOS matrices were compared with CCD matrices in terms of photosensitivity, but they turned out to be more energy efficient and devoid of the main drawback of CCD technology - the “fear” of point light. In 2009, Sony improved its EXMOR CMOS sensors with "Backlight illumination" technology. The idea of ​​the technology is simple and fully corresponds to the name.
• The photodiode of the matrix cell has a relatively small size, and the value of the resulting output voltage depends not only on the parameters of the photodiode itself, but also on the properties of each pixel element. Thus, each pixel of the matrix has its own characteristic curve, and the problem of scatter arises

CCD and CMOS sensors have been in constant competition for the past few years. In this article we will try to consider the advantages and disadvantages of these technologies. A CCD matrix (abbreviated from “charge-coupled device”) or CCD matrix (abbreviated from the English CCD, “Charge-Coupled Device”) is a specialized analog integrated circuit consisting of photosensitive photodiodes, made on silicon, using CCD technology - charge-coupled devices. In a CCD sensor, the light (charge) incident on a sensor pixel is transmitted from the chip through a single output node, or through just a few output nodes. The charges are converted to a voltage level, accumulated and sent out as an analog signal. This signal is then summed and converted into numbers by an analog-to-digital converter, outside the sensor. CMOS (complementary logic on metal-oxide-semiconductor transistors; CMOS; Complementary-symmetry/metal-oxide semiconductor) is a technology for constructing electronic circuits. At an early stage, conventional CMOS chips were used for display, but the picture quality was poor due to the low light sensitivity of CMOS elements. Modern CMOS sensors are manufactured using more specialized technology, which has led to rapid growth in image quality and light sensitivity in recent years. CMOS chips have a number of advantages. Unlike CCD sensors, CMOS sensors contain amplifiers and analog-to-digital converters, which significantly reduces the cost of the final product, because it already contains all the necessary elements to obtain the image. Each CMOS pixel contains electronic converters. CMOS sensors have greater functionality and greater integration capabilities. One of the main problems with using CMOS sensors in video cameras was image quality. CCD matrices provided and now provide lower noise levels. As a result, CMOS chips performed extremely poorly in low light compared to CCD chips. And since low light is one of the main difficulties in video shooting, this has been a major barrier to the use of CMOS sensors. However, the manufacturing experience accumulated over the years of CMOS development has made it possible with each new generation of these sensors to significantly reduce fixed and random noise that affects picture quality. Another weak point of CMOS is the distortion that appears when capturing a dynamic image due to the weak sensitivity of the sensor. Car images may contain very bright elements such as headlights, the sun, as well as very dark areas such as license plates. For this reason, a wide dynamic range is required to process scenes with large contrast differences. The CCD sensor has good dynamic range, but CMOS's access to individual pixels gives it much more room to achieve better dynamic range. Also, when using CCD matrices, bright spots in the scene can create vertical lines in the picture and interfere with license plate recognition due to fading and blurring. Despite the fact that CCD matrices have a higher sensitivity characteristic, the main factor limiting their use is the low charge readout speed and, as a consequence, the inability to provide high image formation speed. The higher the matrix resolution, the lower the image formation speed. In turn, CMOS technology, which combines a photosensitive element and a processing chip, allows for high frame formation speed even for 3 MP sensors. However, the use of megapixel CMOS sensors for IP cameras in video surveillance systems requires effective compression of the data stream. The most common compression algorithms in IP CCTV currently are M-JPEG, MPEG4 and H.264. The first is often implemented directly on the CMOS sensor by the matrix manufacturer itself. MPEG4 and H.264 algorithms are more efficient, but require a powerful processor. To generate a real-time stream with a resolution of more than 2 megapixels, CMOS IP cameras use coprocessors that provide additional calculations. Currently, IP cameras based on CMOS sensors are becoming increasingly popular, primarily due to the support of the technology from the leaders of IP video surveillance. However, their cost is higher than similar CCD cameras. This is despite the fact that CMOS technology, which combines analog and digital parts of the device, allows for the creation of cheaper cameras. The situation is that today the cost of an IP camera is determined by its capabilities and characteristics. What is important is not the type of matrix, but the software implemented by the camera processor.

Advantages of CCD matrices: Low noise level, high pixel fill factor (about 100%), high efficiency (the ratio of the number of registered photons to their total number incident on the photosensitive area of ​​the matrix, for CCD - 95%), high dynamic range (sensitivity), good sensitivity in the IR range.

Disadvantages of CCD matrices: Complex principle of signal reading, and therefore technology, high level of energy consumption (up to 2-5W), more expensive to manufacture.

Advantages of CMOS matrices: High performance (up to 500 frames/s), low power consumption (almost 100 times compared to CCD), cheaper and easier to manufacture, promising technology (on the same chip, in principle, it costs nothing to implement all the necessary additional circuits : analog-to-digital converters, processor, memory, thus obtaining a complete digital camera on a single chip).

Disadvantages of CMOS matrices: Low pixel fill factor, which reduces sensitivity (effective pixel surface ~75%, the rest is taken up by transistors), high noise level (this is caused by the so-called tempo currents - even in the absence of illumination, quite a significant current flows through the photodiode) to combat which The low dynamic range makes the technology more complex and expensive.

Like any technology, CMOS and CCD technologies have advantages and disadvantages, which we tried to consider in this article. When choosing cameras, it is necessary to take into account all the pros and cons of these technologies, paying attention to such parameters as light sensitivity, wide dynamic range, power consumption, noise level, and camera cost.

CMOS matrix- photosensitive matrix, made on the basis CMOS technologies.

CMOS matrix

CMOS matrices use field effect transistors with an insulated gate with channels of different conductivity.

Equivalent circuit of a CMOS matrix cell: 1 - light-sensitive element (diode); 2 - shutter; 3 - capacitor that retains charge from the diode; 4 - amplifier; 5 - line selection bus; 6 - vertical bus transmitting a signal to the processor; 7 - reset signal.

Story

The exact date of birth of the CMOS matrix is ​​unknown. At the end of the 1960s. Many researchers have noted that CMOS structures are sensitive to light. However charge coupled devices provided such higher photosensitivity and image quality that CMOS technology matrices did not receive any noticeable development.

In the early 90s, the characteristics of CMOS sensors, as well as manufacturing technology, were significantly improved. Progress in submicron photolithography allowed the use of thinner connections in CMOS sensors. This led to an increase in photosensitivity due to a larger percentage of the irradiated matrix area.

A revolution in CMOS sensor technology occurred when NASA's Jet Propulsion Laboratory (JPL) successfully implemented Active Pixel Sensors (APS). Theoretical studies were carried out several decades ago, but the practical use of an active sensor was pushed back until 1993. APS adds a transistor readout amplifier to each pixel, making it possible to convert charge into voltage directly at the pixel. This also provided random access to photodetectors, similar to RAM implemented in microcircuits.

As a result, to 2008 CMOS have become almost an alternative to CCDs.

Principle of operation

Before shooting, a reset signal is given

During exposure, charge is accumulated by the photodiode

During the reading process, the voltage value on the capacitor is sampled

Advantages

Main advantage CMOS technology - low power consumption in a static state. This makes it possible to use such matrices as part of non-volatile devices, for example, in motion sensors and surveillance systems that spend most of the time in “sleep” or “waiting for an event” mode.

An important advantage of the CMOS matrix is ​​the unity of the technology with other digital elements of the equipment. This leads to the possibility of combining analog and digital parts on one chip, which served as the basis for creating miniature embedded cameras for a wide variety of equipment and reducing their cost.

Using a random access mechanism, selected groups of pixels can be read. This operation is called framed reading ( English windowing readout). Cropping allows you to reduce the size of the captured image and potentially increase readout speed compared to CCD sensors, since in the latter all information must be downloaded for further processing. It becomes possible to use the same matrix in fundamentally different modes. In particular, by quickly reading only a small part of the pixels, it is possible to provide a high-quality live image viewing mode on the screen built into the device with a relatively small number of pixels. You can scan only part of the frame and apply it to display on the entire screen. Thus, you will be able to achieve high-quality manual focusing. It is possible to conduct high-speed reportage shooting with a smaller frame size and resolution.

In addition to the amplifier inside the pixel, amplification circuits can be placed anywhere along the signal path. This allows you to create amplification stages and increase sensitivity in poor lighting conditions. The ability to change the gain for each color improves, in particular, white balancing

Flaws

The cell photodiode occupies a significantly smaller area of ​​the matrix element compared to Full frame transfer CCD. Therefore, early CMOS sensors had significantly lower light sensitivity than CCDs.

The photodiode of the matrix cell has a relatively small size, and the value of the resulting output voltage depends not only on the parameters of the photodiode itself, but also on the properties of each pixel element. Thus, each pixel of the matrix has its own characteristic curve, and the scatter problem arises photosensitivity And contrast ratio matrix pixels. As a result, the first CMOS matrices produced had a relatively low resolution and a high level of so-called “structural noise” ( English pattern noise).

The presence of a large volume of electronic elements on the matrix compared to the photodiode creates additional heating of the device during the reading process and leads to an increase in thermal noise.

The camera, features, advantages and disadvantages of such matrices.

To the advantages CCD matrices can be attributed:

• High pixel area utilization rate (close to 100%);
• relatively low;
• very high efficiency;
• big enough .

To the disadvantages CCD matrices relate:

• high energy intensity;
• a rather complex process of reading information;
• expensive production.

Modern digital cameras use not only CCD-based matrices, but also CMOS matrices, the share of cameras equipped with such matrices is constantly growing.

CMOS matrix of the camera.

Back in the late 60s of the last century, scientists knew the property of CMOS structures to perceive light. However, CCD structures provided much higher sensitivity to light and high image quality. This is why matrices based on CMOS technology have not become so widespread. In the early 90s characteristics CMOS matrices and their production have been significantly improved, leading to wider adoption of these matrices. Revolutionary discoveries were made at NASA's Jet Propulsion Laboratory (JPL), where Active Pixel Sensors (APS) were created. The bottom line was that a transistor signal amplifier was added to each, which made it possible to convert charge into voltage directly in the pixel itself. Thanks to this, random access to individual pixels became possible, in principle similar to RAM circuits.

As a result, by 2008, matrices based on CMOS elements had become an alternative to CCD matrices.

A CMOS matrix (complementary metal-oxide-semiconductor structure), in English transcription - CMOS (Complementary metal oxide semiconductor), is in principle similar to a CCD matrix. Just like in a CCD, electrons are created under the influence of light.

CMOS matrix cells are field-effect transistors with an insulated gate and have channels of different conductivity.

Unlike a CCD element, each cell CMOS matrices has additional electronic devices called pixel binding, which allow the charge to be converted into voltage directly in the cell.

Figure 1 shows the equivalent circuit diagram of a CMOS element.

Fig.1. Equivalent electrical circuit of a CMOS element.

1 - LED. 2 - electronic shutter. 3 - capacitor that accumulates charge from the photodiode. 4 - signal amplifier. 5 - line reading bus. 6 - bus through which the signal is transmitted to the processor. 7 - reset signal line.

The operating principle of the above circuit:

before taking an image, a reset signal is sent through line 7;

when light is exposed to a photodiode, a charge is created in it in proportion to the intensity of the light flux, which charges the capacitor;

The signal is read from the element by discharging the capacitor, the resulting current is transferred to the amplifier and then to the processing circuit.

Synchronization of the matrix operation is carried out through the address buses of columns and rows.

Thanks to this scheme, it becomes possible to read the charge immediately from a group of pixels (and not sequentially cell by cell, as in a CCD matrix) or even selectively from individual pixels. In such a matrix there is no need for column and row shift registers, which greatly speeds up the process of reading information from the matrix. The energy consumption of the matrix is ​​also significantly reduced.

Progress in the development of technologies, in particular the production of high-quality silicon wafers and the improvement of the amplifier circuit of the CMOS element, has led to the fact that the quality of the resulting image has reached almost the same level as the CCD element.

Advantages of CMOS matrix:

First of all, power consumption is significantly reduced, due to the fact that in a CMOS matrix the information processing chain is not as long as in a CCD matrix; the CMOS matrix is ​​especially low in power consumption in static mode.

The CMOS matrix cell design allows it to be integrated directly with an analog-to-digital converter and even with a processor. This creates the possibility of combining both analog and digital circuits and processing circuits in one chip. Thanks to this, further miniaturization of digital cameras has become possible, reducing their cost due to the absence of the need for additional processor chips.

The ability to randomly access CMOS cells allows individual groups of pixels to be read. This feature is called cropped reading, i.e. reading only part of the entire frame, in contrast to a CCD matrix, where the entire matrix must be unloaded to process information. Thanks to this, to ensure quick viewing of the image, only part of the information can be displayed on the camera’s built-in display with a relatively small number of pixels. This will be enough for viewing; you can control the focusing accuracy, etc.

In addition, for faster reportage shooting, you can conduct it with a smaller frame size and lower resolution.

Another advantage of a CMOS matrix is ​​the ability to add more amplification stages to the amplifier inside the CMOS element, thereby significantly increasing the sensitivity of the matrix. And the ability to adjust the gain for each color allows you to improve.

The production of CMOS matrices is simpler and cheaper than CCDs; almost any plant involved in the production of microelectronics can master it. This is especially true when producing large matrices.

Disadvantages of CMOS matrix:

The disadvantages of a CMOS matrix compared to a CCD matrix include, first of all, the reduction in the light-sensitive part of the element due to the presence of electronic binding around the pixel. This is why at first CMOS matrices had significantly lower sensitivity than CCD matrices. The situation changed with the development and launch by Sony in 2007 of CMOS matrices made using EXMOR technology, previously used for specific devices such as electronic telescopes. The size of the photosensitive part of the pixel was increased by moving the electronic trim to the bottom layer of the element, where it did not interfere with the entry of light. This led to an increase in the sensitivity of each pixel and the entire matrix.

Each of the elements of the CMOS matrix also contains electronic elements, which, due to the properties of electronic circuits, have their own noise, and this noise is added to the noise of the photosensitive element itself. Moreover, for each pixel the level of this noise is different.

The magnitude of the signal received from each pixel depends not only on the characteristics of the photodiode itself, but also on the properties of each element of the electronic wiring of the pixel. It turns out that each CMOS element has its own