Design Article
Under the Hood: JVC Digital Videocam offers a cast of analog players
David Carey, President, Portelligent (www.teardown.com)
10/8/2004 7:03 PM EDT
The GR-DV3000 digital video camera from JVC represents an emerging breed of hybrid still/video digital image-capture devices which rely heavily on support from the analog world. Capable of capturing megapixel stills and electronically-stabilized video through the fast 10X optical zoom lens, the JVC sports both an electronic LCD viewfinder and a sizable 3.5" swing-out LCD to enjoy playback of your video masterpiece. The camera captures four modes of JPEG-compatible still images onto an SD/MMC memory card and records two modes of MPEG4 compatible video to the Mini-DV cassette.
There are a total of 12 high-density circuit boards in the GD-DV3000 design, with numerous controllers, memories, and DSPs to support image processing, coding/decoding, and storage. Nevertheless, pictures start in the analog domain and an extensive frontend to feed the digital pipeline is needed. A Sony CCD Image Sensor (#ICX286) combined with a Sony CCD Timing Controller (#CDX3602) deliver a brigade of low-level analog signals for sensor readout—specifically color and intensity values for each pixel.
This pixel-stream is subsequently fed to a Renesas Hitachi Analog Image Processor (#HD49334), which controls noise through correlated double sampling (CDS) of each pixel, boosts signal levels in a programmable gain amplifier (PGA), and converts the pre-processed signal into a 10-bit data stream with its internal A/D converter. Separate digital engines for video and stills are used downstream.
In addition, the many optomechatronic elements of the design—lenses, tape transports, shutter/iris mechanisms, and the like—all require analog control. An NEC Stepper Motor Driver (#uPD16879) orchestrates movement of the nine glass elements in four groups to affect zoom and focus of the optical train. Control of capstan, readwrite, and transport motors in the Mini-DV assembly is handled with a Rohm analog controller (#BD6630KV), while a Sony R/W head front end (#CXA3521) manages the bridge between signal processing and signal delivery to/from the tape. Along with a myriad of power management components, two AKM CODEC chips (#AK4550), a Rohm D/A Converter (#BU2501FV), and a Sanyo Audio Interface (#LA74202W) represent other key analog ICs in the system.
Numerous components and assemblies are not shown, as total component count and electronics complexity in the GR-DV3000 is quite high—consistent with the highfunction nature of the camcorder/DSC combo product. Filling the gaps between all of the embedded digital horsepower and the real world are many of the usual suspects from the analog component supply community.
David Carey is President of Portelligent. The Austin, Texas company produces teardown reports and related industry research on Wireless, Mobile, and Personal Electronics. (www.teardown.com)
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