Conventional CMOS image sensors mount the pixel section and analog logic circuit on top of the same chip, which require numerous constraints when wishing to mount the large-scale circuits such as measures to counter the circuit scale and chip size, measures to suppress noise caused by the layout of the pixel and circuit sections, and optimizing the characteristics of pixels and circuit transistors.
ENGADGET: Sony's new cameraphone CMOS jams bigger gear into the same space (video)