Strictly speaking, the IMX789 and IMX888 are not directly related, after all, the latter is based on the noble dual-layer transistor technology, and the focusing technology is also different - changed to all-pixel octa-core focusing. However, the basic parameters between IMX888 and IMX789 are extremely consistent, so when the Huawei P60 series was released, everyone thought it was equipped with IMX888, but it turned out to be an oolong. Be careful, thoughThe P60 series uses the RYYB version of the IMX789 (with a 40% sensitivity buff).
It is precisely for this reason that these two can be summarized in one article for easy analysis. In addition, the IMX689, the predecessor product related to IMX789, and the modified product LYT-808 are also included.
The basic parameters of the IMX689 are 1 143 inches, 48 million pixels, 112μm, with Quad Bayer arrangement, 4:3 format, 12-bit ADC, support QBC 3-HDR, dual native ISO, double conversion gain, all-pixel omnidirectional focus, and other technologies.
Just looking at these descriptions, there may not be any specific concepts, but if you put it this way:
Its all-pixel omnidirectional focus is the industry's first new technology, and it is the first to use dual native ISO technology on a mobile phone, and it is also one of the few sensors with a 12-bit ADC on the mobile phone.
In this way, isn't it very good?Even though it has been nearly four years since its release, its hardware parameters are still bright.
Next, let's look at the IMX789 a year later, what has been upgraded, which has cost OnePlus hundreds of millions of yuan in customization costs.
The first is that the size of the base is increased to 1 135 inches, but the frame ratio has been changed to 16:11. In addition, high-end features such as Dol-HDR and 4K 120fps** shooting (the first in the world) have been added.
This means that when taking a photo, an imaging area equivalent to the IMX689 format will be cut out at a ratio of 4:3 (corresponding to 1 143 inches). By cropping, you can also effectively control the image quality of the corners.
In ** shooting, more pixels can be utilized at a 16:9 ratio for better electronic image stabilizationCoupled with the upgrade of HDR technology and ** shooting specifications, the upgrade direction of this generation is obvious.
As you can see from the above figure, the format design of the IMX888 is exactly the same as that of the IMX789, and the basic parameters are exactly the same - all are 1 135 inches, 52 million pixels, 112 microns.
The benefits of this format design are also specifically given: the format area that can be used when shooting ** can reach 1 1The level of the 31-inch sensor is still 142% of the IMX766 level (in fact, it is only 30% larger).
So why can the IMX888 achieve all-pixel octa-core focusing?Generally speaking, at 1It is impossible to place two photodiodes in a small pixel size of 12 microns, and this has to start with the principle of double-layer transistor technology.
First, the reset transistor, amplification transistor, and selection transistor are separated from the pixels of the original photosensitive layer and layered, and then stacked under the photosensitive layer using through-silicon via technology (the second layer on the left in the image above).
The transistor layer is then stacked with the ISP circuit layer via copper interconnect DBI technology (the top layer on the left in the image above), so that only the photodiodes and transmission transistors are left in the photosensitive layer at the front end, enabling the ultimate vertical stacking system.
As you can also see in the image above, two photodiodes are isolated under a microlens with full-height DTI and grid isolation in the color filter layer, both of which improve dynamic range and focusing performance.
As you can see from the planar perspective above, the TG (transmission transistor) and PD (photodiode) both gain more room for expansion after the three pixel transistors are separated, and the FD (floating diffusion region) capacitance is also increased.
This means that the volume of the amplification transistor can be increased independently, and the dual photodiodes can finally be stuffed into pixels, while the full well capacity can be doubled to 12,000 electrons!
What level is this?The one-inch IMX989 has a full well capacity of 12,000 electrons - you must know that the pixel size of the IMX989 is exactly twice that of the IMX888!In addition, the volume of the amplification transistor has increased, and the noise in low-light imaging has also been significantly reduced!
The result of the dual-layer transistor technology is a huge increase in dynamic range and a significant reduction in imaging noiseIn addition, thanks to the new technology, all-pixel octa-core focusing can be used, which has no drawbacks of loss of resolution in high-pixel mode.
In addition, because Sony launched IMX888, it just wanted to make a model for mobile phone manufacturers to see the "black technology", so the dual native ISO, 12bit ADC and other configurations customized by IMX789 were not used. It was later renamed LYT-800, but it was changed to LYT-T808 not long after.
The LYT-808 equipped by OnePlus and Realme has changed the format ratio of IMX789 to 4:3 (pixel size remains the same), and changed the basic parameters to 1 14-inch, 50-megapixel while also castrating 4K 120fps video and 12-bit ADC.
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