CMOS sensors and crosstalk understanding

The arrival of high-resolution solid state imaging devices, primarily charge-coupled devices (CCDs) and complementary metal oxide semiconductor (CMOS) image sensors, has heralded a new era for optical microscopy that threatens to eclipse traditional image recording technology. As the CMOS imager becomes more specialized, developing a system with such an imager separate from other devices makes the most sense.

For high-end applications where image quality is of primary concern, camera-on-a-chip solutions are proving un-viable, resulting in a market shift toward a system-on-a-chip. Away from research and science applications CMOS image sensors are now available for sophisticated applications such as, cell phones, security cameras, automotive image systems, and digital still camera and video cameras, CCDs sensors offer many benefits, however CMOS sensors now offer almost the same features, CMOS sensors now smaller ship, low cost, high performance, and high integration sensitivity.

In the international markets of CCDs and CMOS sensors the expression (Megapixel) is quite formula, which means in short, the high pixel count in digital still cameras. The pixel crosstalk is high when the photons falling on one pixel are "Falsely" sensed by other pixels around it. For example, we call it crosstalking if we shine highly focused light only on red pixel, and the blue pixel shows a response. In the extreme case the blue channel will appear too high and skew the real pixel color.

Controlling crosstalk is little complicate to discuss in this article but I will demonstrate the idea in short, the color filter and micro-lens of the CMOS sensors can contribute to cross talk, good control of stacks allows high and strong acceptance angels. This micro-lens shift together with wide incident light angel, creates a large number of crosstalk, this method incorporates a physical sensor response model that is based on silicon parameters.

CMOS image sensors, and the quality of the image can be improved by managing the crosstalk with uniformity and sensitivity, however the whole design approach should consider the effect of noise. The list of applications for CMOS image sensors has grown dramatically in the past several years. Since the late 1990s, CMOS sensors have accounted for increasing numbers of the imaging devices marketed in applications due to their ability to capture sequential images at high frame rates.