The new sensor in the iPhone 15 should be particularly exciting because there is now more information that this is a technology that was first presented to the public almost exactly one year ago at the IEEE International Electron Devices Meeting in San Francisco.
Here, photodiodes and the associated transistors are no longer arranged next to each other, but on top of each other on separate substrates (quasi "chip layers"). At the same time, this separation is also supposed to reduce noise, which together allows a theoretical increase of more than one f-stop to be expected.
With previous stacked sensors, there was already a lot of signal electronics in a layer under the photodiodes and the associated transistors, but the fact that the transistors of the sensor itself are now also moving one level lower seems to bring a lot more, according to Sony.
A doubling of the full well speaks for the fact that until now about half of the available sensor area consisted of transistors. This could also be advantageous for aliasing, because it should also significantly reduce the gaps between the sensors.
Sony explains the significant reduction of noise as follows:
"Since the pixel transistors (other than the transfer gates) (TRG) - reset transistors (RST), select transistors (SEL) and amplifier transistors (AMP) - occupy a photodiode-free layer, the amplifier transistors can be enlarged. By enlarging the amplifier transistors in this way, Sony has managed to significantly reduce noise, which is often a problem, especially when shooting at night or in dark environments."
It is said that the new sensor will be manufactured at Sony&s semiconductor plant in Nagasaki from 2023. With the help of this new sensor technology, Sony also wants to get ahead of the competition again and thus raise its market share back to an estimated 60 per cent - after it had fallen to 44 per cent in recent years.
"(...) unfortunately, these extended codec features remain underutilised even with the iPhone 14 Pro, as the sensors simply reach the limits of physics when it comes to dynamics. Although some things can be simulated digitally after the fact, you can usually see the difference quickly and clearly when you take a closer look."
This is not the only reason why an additional f-stop in light sensitivity should suit the iPhone 15 very well, especially since such a large dynamic step is not usually achieved within one generation. At the same time, it will not close the qualitative gap to large sensor cameras. But smartphones are still catching up.
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