In the rat race for ever-higher pixel counts for the digital still camera market, it is clear that, if the chip size must remain constant, then "more pixels" inherently means "smaller pixels."
The driving force to keep the silicon area of the sensor as small as possible is the cost of the sensor chip: Extra silicon costs quite a bit of money. A larger chip size also requires a larger and more costly lens, extra space on a printed circuit board and a larger volume for the camera body. Smaller pixels are the key to producing higher-resolution sensors on the same silicon area -- or to reducing chip size without affecting resolution.
Unfortunately, there are trade-offs in making these improvements and, in this case, the trade-off is the overall performance of the pixels. Irrespective of the sensor technology used -- interline-transfer, frame-transfer or full-frame CCD; or passive- or active-pixel CMOS -- smaller pixels will deteriorate performance...
Meet the author
Albert Theuwissen is R&D manager at Philips Semiconductors Image Sensors in Eindhoven, the Netherlands. He authored the textbook Solid-State Imaging with Charge-Coupled Devices.
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