Thomson Grass Valley Xensium CMOS Provides Unique HD Vision For Today And Tomorrow

Producers are always in search of the best images possible to make their HD productions stand out. That's why shipments of Thomson’s new Grass Valley™ Xensium™ chip, a high performance CMOS (complementary metal oxide semiconductor) imager that will be included in Thomson’s Grass Valley Infinity™ Digital Media Camcorder and future cameras, are eagerly anticipated.

The Xensium imager combines the excellent noise and sensitivity performance normally associated with CCD imagers with the low-power benefits of CMOS technology. Leveraging an array of 2.4 million pixels, the full HD Xensium imager is the first use of CMOS that meets the stringent quality requirements of broadcast applications. Unlike other implementations, the Xensium chip has been designed from the ground up for video acquisition.

Grass Valley and Thomson Semiconductors put together a team of Emmy® Award-winning experts in image processing, analog electronics, silicon process engineering, and systems engineering to help develop the Xensium imager. The chip was developed and designed by Grass Valley engineers in close collaboration with colleagues at Thomson Technology’s Silicon Components division and within a European Union Medea+ program (where it won the highly prestigious Jean-Pierre Noblanc Award for the most innovative project of 2006).

The main thrust of this significant effort is built on the concept that, in broadcast applications, imagers are always coupled with analog-to-digital (A/D) converters and image processing electronics when acquiring TV images. Thomson's engineers have taken an integrated systems approach, including all of the functions of image sensing, A/D conversion, and image control onto a single CMOS imaging chip. These numerous components were designed with reference to each other so that their synergy would produce the best looking pictures.

This breakthrough in imaging technology was made possible because Thomson owns the design for each major component in the chain. It also avoids having to rely on third-party fabricators, which keeps costs down, ensures reliable delivery schedules, a high degree of quality control and maps out the route for future in-house imager developments.

Enhanced Feature Set

The Xensium chip offers a wider dynamic range, lower power consumption, and improved signal-to-noise performance when compared to current CMOS imagers. Thomson has worked hard to achieve high resolution, wide contrast handling, and low noise. The first application of Xensium technology is an imager designed specifically for full-resolution HD image capture. The chip also includes control electronics that allow for on-chip pixel manipulation. This means that it can capture natively in both progressive and interlaced formats. The imager also incorporates on-board analog-to-digital conversion, further reducing noise and improving performance by eliminating a separate processing stage.

The introduction of the Xensium chip marks the first time Thomson has moved from CCD to CMOS technology in its cameras. Coupled with Grass Valley's comprehensive digital signal processing, Xensium delivers remarkable pictures in uncompromised HD resolution. The 2/3-inch 1920 x 1080 active pixel Xensium HD imager, with 16:9 aspect ratio, will first be used in production models of the Grass Valley DMC 1000 Infinity camcorder but the Xensium line of imagers—with their on-board control electronics and A/D converters—are likely to become a standard in future generation Grass Valley camera products across a broad range of applications.

The readout circuits of the Xensium chip are fully programmable to support true interlace and true progressive scan modes. This means that the spatial offset between lines in successive interlaced fields is correct. Compare this with other solutions that synthesize interlace fields from imagers that can only operate progressively. In progressive mode, every line scanned is enabled, which means that the image captured is truly progressive.

Putting A/D Converters Where They Belong--On The Imager!

Normal imager designs require the A/D conversion to be done off-chip. This means that high speed, analog signals have to travel over wires to the A/D conversion circuitry, and pick up noise along the way. By putting the A/D converters on-chip, this source of noise is significantly reduced and in many cases almost eliminated completely.

The Xensium also features a noise reduction technique called "Double Digital Sampling." This helps improve noise performance from 30 electrons down to 11 electrons. This pioneering system chip design has resulted in the Xensium using only four electrons for every pixel. It has also helped to remove the 2.4 million threshold differences, which in turn results in a superb image.

The Xensium chip also utilizes powerful driving circuits that produce an image with no lag, no smear, and a built-in "randomizer" to reduce ground bouncing. This patented technology minimizes differences in electric current charges that can cause signal degradation. And it supports higher exposures for camera operators.

Finally, Xensium offers real interlace support, which adds pixels at the columns (like a CCD) instead of in the digital domain. This again ensures the best image capture possible for HD productions.

40 Years of Proven Experience On A Chip

The difference between the Grass Valley Xensium and other CMOS imagers is that the Xensium was designed by a team of experts with more than 40 years of experience in image processing and integrated circuit design. Many competing designs offer shortcomings that the Xensium, with its integrated component architecture, has been designed to overcome.

For Thomson, CMOS is clearly the way of the future, as CCD chips become harder and more costly to manufacture and maintain. The CMOS imager’s advantages over CCD bring new value and performance to the Grass Valley DMC 1000 Infinity camcorder that cannot be met by any other camera in this price range.

Because sports production involves the capture of fast action, the Xensium chip is the ideal tool to ensure the highest quality. For sports producers, that means a "quieter" (better signal-to-noise ratio and dynamic range) picture that shows HD in all its widescreen, full resolution glory.