Entry-level camera delivers

The high end of any market usually gets the buzz, but it's the low end that normally gets the buyers. In today's digital still camera market, entry-level products perform like yesterday's high-end devices. To wit, at a modest $150 or so best street price, the 3-Mpixel, 3x optical-zoom Fujifilm A330 packs a surprising punch without punching a hole in that retirement fund. Take into account the savings achieved by sidestepping development of film and unwanted prints, and the price looks even better, particularly in the cutthroat point-and-shoot category.

In response, manufacturers have looked to highly integrated digital camera engines, declining memory prices and expanding sensor capabilities as a means of lowering their manufacturing costs and achieving survivable margins.

Starting with the A330's CCD image sensor from Matsushita (part number MN39480), we see reductions in pixel size to lower sensor area and cost, and to bring quite usable resolution to the mass market. The low-level analog-signal output of the CCD is passed to the Renesas HD49334 CCD analog front end, which takes care of gain control (think exposure), correlated double sampling (think noise and speckle reduction in the image), along with signal conversion from the analog to the digital world for further processing. A mixed-signal part from Fuji (the MD2174) is responsible for orchestrating the precise timing and readout of signals from CCD to analog front end.

Before any real images are captured, a rather amazing control loop takes place among sensor, image processor and optics to ensure that zoom, focus, shutter and iris in the lens assembly are all properly set-a task left, in this case, to the Renesas M50239 multichannel motor driver.

Digital still cameras can now rely on purpose-built imaging engines for digital signal processing and, here again, a Renesas part (FF4170) does the heavy lifting. Its multichip package contains 16 Mbytes of SDRAM along with the image processor; the latter is supported by 2 Mbytes of external STMicroelectronics NOR flash memory (M28W160CT) for code storage.

On the opposite side of the processor board is the power control ASIC (AN30202A) from Matsushita. Along with a number of other small-scale power-management devices, the Matsushita device generates the often-complex matrix of bias voltages required for CCD imager chips.