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1.3Mpixel sensor improves image quality for camera phones

Posted: 28 Feb 2006 ?? ?Print Version ?Bookmark and Share

Keywords:ADCC-3000? image sensor? camera phones? Avago Technologies? Gina Roos?

Avago Technologies raises the price and performance bar with its 1/4-inch optical format, 1.3Mpixel CMOS image sensor for camera phones. Leveraging the company's enhanced-performance (EP) pixel architecture and image-pipe processing (I-Pipe) technology, the company has unveiled the ADCC-3000 image sensor at the recent 3GSM World Congress, touting much better picture quality than existing megapixel sensors for camera phones.

Key features of the ADCC-3000 image sensor is its true color under changing lighting conditions, enhanced colors and lower noise in low light conditions, like CCD products, along with a low cost and low power consumption in a very small module size. In addition, the image sensor is one of the few 1.3Mpixel sensors that fits into the industry's smallest 8 x 8 x 5-mm low-profile camera modules.

This makes the 1,280 x 1,024 ADCC-3000 a good fit for ultra-thin Mpixel cellphones. The image sensor is capable of 15fps at full 1,280 x 1,024 pixel SXGA (super extended graphics) resolution, and 30fps in 640 x 480 pixel VGA mode.

"We focused on creating a new kind of Mpixel image sensor that would offer the performance equal to CCD-quality cameras and also be small enough to match the needs of the camera phone which are evolving into much thinner devices," said Feisal Mosleh, director of Avago's mobile imaging marketing. "We think the pixel wars are a waste of time like the MHz wars that occurred in the PC world. You need to get the image quality right because megapixel is good enough to give you very good image quality."

As a result, Avago focused on improving image quality within the unique constraints of the camera phone market. What this means is that a camera phone must fit into a very small space; consume minimal power; conserve battery life; be capable of withstanding strong mechanical shock; have few moving parts and be extremely reliable, Mosleh explained.

What really matters to the user is image quality. Based on a survey of camera phone users, Mosleh said people aren't sharing pictures primarily because of the high cost of sending them and low image quality. The ADCC-3000 answers their needs by providing vivid color, bright exposure, no noise or distortion, sharpness and contrast, which all contribute to its digital still camera-like quality.

Touted as outperforming 1-, 2- and 3Mpixel sensors at all light levels, the company said the advanced Mpixel sensor and fully integrated SoC is the "only 1/4-inch Mpixel image sensor capable of producing high-quality, digital still camera-like images and camcorder-like video," while fitting into ultra-slim camera phones. This also means that the ADCC-3000 can replace a 1/4-inch VGA sensor in handset designs, giving designers a four times increase in resolution, and providing users with sharper, true color photos under all lighting conditions.

Avago has incorporated several features that give the image sensor its good image quality. These include auto illuminant detection that adjusts automatically to any light for better whites and colors, and adaptive tone mapping that provides a dynamic range expansion for better contrast and more vivid colors. The advanced auto exposure brightens dark photos and vice versa without distortion. The company's FastAutoFocus feature provides the ability to focus rapidly while FastLane reduces image lag for action shots and video.

The ADDC-3000 also provides enhanced automatic pixel correction, noise reduction, true color imaging, and true black (CCD-like black which translates into better black-white contrast). Other features include programmable, dual-LED and Xeno flash strobe synchronization, 4x digital zoom to emulate an optical zoom, a special-effects generator, anti-vignetting and auto-flicker correction.

The ADCC-3000 is also Avago's first product to incorporate both the EP pixel architecture and I-Pipe image processing technology. These technologies are the key reason behind the sensor's quality. The EP pixel architecture reduces dark current and noise, and removes the lens shading effect to offer low-light CMOS sensor performance that rivals CCD sensors. In addition, the new dynamic range expander enables better contrast, and a new proprietary exposure control adjusts picture brightness without increasing noise linearly or washing out colors.

As for the I-Pipe technology, the image-pipe processor is specifically tuned to Avago's EP pixel architecture and accommodates a wide range of lighting conditions. Since the CMOS sensor is tightly coupled with the CMOS sensor, it results in several advantages: better colors, higher contrast, truer skin tones and picture rendering that is highly adaptive to varying light, shadows and movement.

Size is also important. The ADCC-3000 enables a true 8-by-8mm low-profile module with a z-height of 5mm to 6mm. "Today's Mpixel sensors cannot support a thin module because they are usually quite large on the x and y dimensions, which means the optical format (lens size) is large," Mosleh said. "If the lens is large so is the lens thickness which is the predominant factor in determining the z height."

Avago was able to create a super thin lens by making advances in pixel design and sensor array layout design. "It's all about design, compression and efficiency of the layout," Mosleh said.

Mosleh said Avago entered the digital still/video-quality arena by primarily using three key featuresFastLane for video and action shots, NiteVision for better performance in low light conditions, and DSC features such as auto focus, advanced exposure control, dynamic range expansion through extended dynamic range and automatic illuminant detection, he said.

The ADCC-3000 1.3Mpixel sensor is priced at less than $3.25 each in quantities of 1,000,000. Samples and volume production are available in February 2006.

- Gina Roos

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