Samsung unveils the new 12MP sensor that lets Galaxy S9 do its Super Slow Motion magic

Basically, the new 12MP Samsung ISOCELL Fast 2L3, which is already in mass production (duh), has its own stack of fast DDR4 memory attached under the typical analog logic layer that processes the electric signal coming from the pixel array layer above it, into digital code. The 3-stack setup is needed because recording 960fps slow-motion video results in a gigantic amount of frames that have to be stored and process quickly, and sending them to the chipset to process, and storing them in the phone's regular RAM would gum up the speed required to record the Super Slow Motion footage that the S9 is capable of. 

Sony uses a very similar solution for its own slow-motion solution since the Xperia XZ Premium, and does have the option in its new XZ2 and its Compact version, too. Samsung, however, is taking advantage of the third memory layer stacked directly onto the CMOS sensor further, by using it to also store imagery of fast-moving objects, avoiding the typical blur and jello effects that come with such capture. 

In addition, the ultrafast sensor storage allows for 3-Dimensional Noise Reduction (3DNR) for brighter, noise-free pictures in low-light, and enhanced real-time HDR imaging, all aided by the record wide f/1.5 aperture on the Galaxy S9 and S9+, which on top of that is of a variable type, and can be shrunk to f/2.4 when there is enough light around. We already previewed the S9 camera with some samples from the MWC, and the results from Samsung's newest ISOCELL Fast 2L3 sensor are very encouraging.

source: Samsung