The Apple A15 with 15 Billion Transistors
Technology 73

The Apple A15 with 15 Billion Transistors

The Apple A15 with 15 Billion Transistors

In addition to Apple’s new iPhone, iPad, and Apple watch products, Apple’s new A-series chip-A15 is of course indispensable. According to Apple, this new processor will become “the fastest chip in a smartphone.”

From Apple’s past press conferences, the new generation of processors usually use smaller process nodes. It’s because this allows the use of more transistors, resulting in faster performance. However, the A15 uses the same 5nm manufacturing process as the A14, which indicates that the performance improvement here may not be as large as previously hoped.

Apple did not specify which node variant the A15 uses. We suspect that it will use the new N5P node, which is an iteration of the N5 node last year.

The transistor density of TSMC’s N5 is approximately 170 million transistors per square millimeter, which will make it the highest density technology available today. As for its upgraded version of N5P, TSMC promised to increase the frequency at this node by up to 5%, or reduce power consumption by up to 10%, and increase the density by 1.8 times. This new node variant provides customers with a seamless migration path, which means that customers do not need a large investment in engineering resources or a longer design cycle, so any user who uses N5 design can use N5P. For example, early adopters of N5 can reuse their IP for N5P chips.

With the support of this new process, the number of transistors in the Apple A15 processor has reached 15 billion, which is a significant increase from the 11.8 billion of A14.

CPU of A15

The new chip still follows Apple’s 2+4 CPU configuration design, which has been used in past generations of products. Two of them are performance cores and four are efficiency cores. At this year’s press conference, Apple did not disclose much information about the new CPU this year. Regarding the performance of the chip’s CPU, Apple did not provide comparison data with the previous generation A14 chip. Instead, it chose to compare itself with competitors’ Chip comparison, this has rarely happened in the past. According to Apple, the company’s chips are 50% faster than their closest competitors in terms of CPU performance.

A15 CPU

According to anandtech’s report, Apple’s next best competitor here is Qualcomm’s Snapdragon 888. If we look at our SPECint2017 benchmark test results, we can see that the performance of the A14 is 41% higher than that of the Snapdragon 888. In other words, for A15, if the gap widens to 50%, it means that it only needs to be 6% faster than A14, which is really not a big upgrade.

In the press conference, Apple also did not comment on any new ISA features, such as whether it is Armv9/SVE2, all of which have to be verified in the future.

Anandtech also pointed out that at the beginning of 2019, Apple lost their chief architect (Gerard Williams III) and part of their CPU design team, who founded Nuvia, which was acquired by Qualcomm at the beginning of this year. Anandtech said that although it is uncertain, the time gap here can definitely match the time to market of the new CPU. And this is also the first sign of brain drain and team reorganization. It is worth noting that Apple continues to hire Mike Filippo, Arm’s chief architect. It means that they may be developing a new CPU series.

Another theory is that given its huge lead in CPU performance, Apple decided to focus more on reducing the power consumption and energy efficiency of this generation of products. This is actually a more popular theory, but we still can’t confirm it now.

GPU of A15

When it comes to GPU, according to reports, A15 is the first SoC with two performance versions. The ordinary iPhone 13 mini and iPhone 13 are equipped with an A15 equipped with a 4-core GPU. The Pro model is equipped with a 5-core GPU configuration. In fact, if I remember correctly, this will be the first time we have seen such an SoC on a mobile phone because I don’t remember any company doing this before today.

A15 GPU

Like the CPU, Apple did not provide a comparison with the A14. According to Apple, the quad-core GPU is 30% faster than the competition. If we take GFXBench Aztec as a benchmark, we see that the A14 is about 18% faster than the Snapdragon 888. That means A15 needs to be 10% faster than A14 to achieve this advantage. The faster 5-core A15 is as being 50% faster than the competition. That is actually a 28% performance improvement over the A14. And it is more in line with Apple’s generational growth over the past few years.

Apple also mentioned many other SoC improvements, such as mentioning that they doubled the system level cache (SLC) to about 32MB. There is also a new display engine that may handle 120Hz, as well as new video decoders and encoders. Apple also did mention hardware ProRes support.

Finally, the neural engine of Apple’s new chip still has 16 cores. They have increased its performance to 15.8 TOPs, surpassing the 11 TOPs of the previous generation chip.

Overall, this is a good chip.

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Technology 73