The Apple iPhone 6s and iPhone 6s Plus Review
by Ryan Smith & Joshua Ho on November 2, 2015 8:00 AM EST- Posted in
- Smartphones
- Apple
- Mobile
- SoCs
- iPhone 6s
- iPhone 6s Plus
Dual Sourcing A9: Two for the Price of Two
Perhaps more remarkable than the fact that the A9 is built using a FinFET process however is who it is being built by. For the first time Apple is dual sourcing the SoC – rather than using TSMC or Samsung exclusively, they are using both.
Broadly speaking, dual sourcing is a practice that has fallen out of style as the number of contract semiconductor manufacturers has dwindled and the cost of chip production has gone up. Because each manufacturer has its own rules and own best practices, to dual source a chip involves designing it twice, once for each manufacturer. This has made the cost of dual sourcing increase over time, and consequently dual sourcing falling out of fashion.
This of course is a big part of what makes Apple’s decision to dual source so unexpected. Apple is taking a much bigger gamble this time around by dual sourcing than they have on past SoCs where it was produced by a single manufacturer (be it TSMC or Samsung). Dual sourcing means that Apple’s costs to tape-out and bring-up A9 have very nearly doubled; they have to tape-out each version of the A9 for the respective fab’s rulesets, and then they have to go through the bring-up process with each in order to dial-in the yields and clockspeeds. They at least get to reuse the underlying architecture (e.g. Twister CPU and their PowerVR GPU), but actually creating a chip design for each fab is a significant part of the development costs for A9.
Samsung vs. TSMC A9 Die Size (Image Courtesy Chipworks)
The end result then is two similar but not quite equal chips that are produced by TSMC and Samsung respectively. Both are A9s, both feature the same CPU, GPU, memory interface, and all of the other bits that make up an A9. But each is produced at a different fab, according to the rules of that fab.
One of the immediate ramifications of dual sourcing is that the die sizes of the A9s are different. The A9 produced by Samsung on their 14nm FinFET Process is the smaller of the two, at 96mm2. Meanwhile the A9 produced on TSMC’s 16nm FinFET process is 104.5mm2, making it about 9% larger. Though not an immense difference in size (and not that we’d expect otherwise) there are tradeoffs to be had. With all other things held equal, the larger TSMC die would produce fewer complete dies per 300mm wafer, and any given die is more likely to have an imperfection since there are fewer dies for the same number of imperfections. This gives the Samsung A9 a slight edge in manufacturing thanks to its better density, however it’s equally important to note that in the real world there are a number of factors at play here, including manufacturing yields at each fab and how much each fab is charging Apple, so while the Samsung A9 is the smaller A9 it isn’t necessarily the cheaper A9.
The bigger question on many minds is whether there’s a performance difference between the two A9s. We wrote a bit on the subject a few weeks back, and the short answer is that it’s very difficult to tell. Due to chip quality being a distribution no two phones utilizing the same A9 are the same, and that means just comparing any two phones can’t tell us the whole story. Ultimately what one needs is a large number of phones to find the distribution, the median of that distribution, and how the medians compare. This is something that if done perfectly would require thousands of phones, and is really only possible for Apple or the competitive analysis teams at their well-funded competitors.
Apple A9 Die Shots (Image Courtesy Chipworks Teardown Report)
At this point then we don’t have anything new to add to the discussion – we don’t have enough data – though it is still a matter we are working on. Sometimes the best thing we can do is say is when we don’t have enough information, rather than extrapolating too much from too little information. I will note however that it’s ultimately in Apple’s best interests for the A9s to be as similar as possible, and there are steps they can take to ensure that, particularly in selecting which chips they will use.
Current A9 Chip Manufacturer Distribution (Image Courtesy Hiraku)
Meanwhile looking at the data collected by iOS developer Hiraku’s CPU Identifier project, it’s interesting to note that of the 250K+ phones sampled so far, the Samsung A9 is in 63% of those phones, giving us a Samsung-to-TSMC ratio of nearly 2-to-1. This survey should not be considered the final word in the ratio between the two A9s since it can change over time and an opt-in survey of this fashion has an inherent self-selection bias, but with so many results it should be a reasonably accurate summary of the current situation.
What remains to be seen – and likely never to be answered outside the walls of One Infinite Loop – is why Apple dual sourced in the first place. We can certainly speculate on reasons they would do this – yield issues at a fab, a desire to avoid putting all of their eggs in one basket and giving one fab too much power, or even just wanting to ramp up A9 production quickly by doubling the number of fabs working on it. What is apparent however is that with Apple selling 48M iPhones in Q3’15 (note that the majority of these were not 6ses), A9 is a uniquely good candidate for dual sourcing. Apple sells enough iPhones that their large pile of cash aside they can absorb the cost of dual sourcing by spreading out the costs over tens of millions of high-margin chips, and if yields/supply were a factor in this decision then that’s all the more reason to dual source. This in turn makes me wonder if we’ll see Apple continue this strategy given their enormous volume, or if this was a one-time event due to the early nature of FinFET, leading to them settling on a single fab for the iPhone 7 launch.
Die Size: Hitting the Sweet Spot
Finally, before jumping into our discussion of the A9’s CPU and GPU, let’s talk about A9’s die size in a historical context. Unlike the transition from A7 to A8, Apple doesn’t get the advantage of a substantial transistor density improvement going from A8 to A9. To use TSMC as an example here (since they produced A8), their 16nm FinFET process is advertised as having 2x the density as their 28nm process, however compared to that same 28nm process their 20nm process had a 1.9x density advantage. In other words, the transition from 20nm HKMG planar to 16nm FinFET does not bring with it the same kind of density improvements we’ve seen in the last few generations.
In fact the only other time Apple has not had the advantage of a density improvement is the transition from A4 to A5, which saw Apple’s die sizes transition from what remains their smallest die to their largest die, all in a single generation. For A9 then Apple has to work smarter, as they can’t add a large number of transistors relative to A8 without ballooning A9’s die size outside of Apple’s sweet spot (and harming chip yields at the same time).
| Apple SoC Evolution | |||
| Die Size | Transistors | Process | |
| A5 | 122m2 | <1B | 45nm |
| A6 | 97mm2 | <1B | 32nm |
| A7 | 102mm2 | >1B | 28nm |
| A8 | 89mm2 | ~2B | 20nm |
| A9 | 96mm2/104.5mm2 | >2B | 14nm/16nm |
Consequently the A9s that we’re getting are surprisingly conservative. The TSMC A9 is 104.5mm2, some 17% larger than the TSMC A8. Meanwhile the Samsung A9 is the smaller of the two at 96mm2. The TSMC A9 is now Apple’s second-largest non-X SoC, but just barely so; it’s only 2.5mm2 larger than the A7. Otherwise with an average die size of 100mm2, this puts the A9 at the upper-bounds of Apple’s sweet spot.
Yet despite the limited gains in transistor density versus A8, Apple has managed to “bulk up” their SoC design by quite a bit. We’ll go over this in greater detail on the following pages, but of particular note is that Apple is now implementing what we believe to be a 6 core PowerVR GPU design, and Apple has significantly increased both the L2 and L3 cache sizes. Coupled with this is the jump to LPDDR4 (requiring more complex memory controllers) and numerous smaller improvements we’ll likely never learn about. The number of CPU cores remains unchanged at 2 however.
Chipworks' Initial Layout Analysis (Image Courtey Chipworks)
My Layout Analysis For A9 (Die Shot Courtesy Chipworks)
On a final note, now that we have die shots of both A9s from Chipworks, I must tip my hat towards Apple for releasing an accurate die shot of what we now know is the Samsung A9 in their iPhone 6s presentation. Up until now Apple has never released their own die shot of their SoCs, and in fact first-party die shots are becoming increasingly rare as a whole in the semiconductor industry. Consequently I had expected that Apple’s die shot was a fake, only to be far more impressed that it’s real. Furthermore despite the low resolution of the shot, Apple’s false color and contrast enhancements make it surprisingly clear where the CPU and GPU blocks are, and how many of each there are. This is a level of contrast that even the Chipworks shots can’t quite match this time around.
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nerd1 - Saturday, November 7, 2015 - link
720p screen in 2015, worse battery life, no sd slot, no wiress charging, terrible camera and still THE BEST phone huh?It has best performing processor, no one argues that, but I still wont touch it with a stick.
JaytB1 - Sunday, November 8, 2015 - link
I use iPhone mainly because of the better security/privacy, no carrier/manufacturer delay/total dismissal of security/OS updates, earlier/exclusive/better releases of triple A games/apps and uncluttered interface. I agree with the gold award, the iPhone 6s (plus) is the first phone in a while that made me see that there are still possibilities to innovate in the smartphone space.I've seen Android users avidly defending their high PPI's, megapixels, core counts. Oh, but it's customizable and I can put a ton of widgets on my homescreens. There's only a small minority of tech obsessed people who care (proof is in the huge low/medium end market share, indicating the amount who don't care for specs but just want a working phone). For me, all I want is to launch an app, not stare at my home screen. In the past, Android users where more often than not boasting about benchmarks and how their hardware was superior. Now that the tables are turned, hardware all of a sudden doesn't matter as much anymore or the tests must be rigged by a biased Anandtech (who has nothing to gain and everything to loose if they were posting nonsense).
I've seen Samsung and other manufactures add so many gimmicks to their phones, many of which are plain impractical (try doing 'airview' while jogging and you'll get the picture).
I admit that fast charging would be nice but, for me, completely unnecessary (it's not like an iPhone charges slow in the first place).
Then there's wireless charging, you do realize that you still have to plug in the charge pad with a cable right? So the only difference is that you don't need to plug that cable into your phone, but you'll need more power to fill your device up as compared to using a cable (more waste power) and a permanent spot for your charging pad. Again, for me I don't really see the appeal for that either.
We could also talk about PPI but to keep it brief, I'd rather have a device perform well with individual pixels I can't distinguish, than a screen that would impact performance with pixels I still can't see... But more of them.
I could go on about how a blind photo evaluation test on a respected Android site had Android users voting the iPhone 6s as having the best overall picture quality, but now that the iPhone scored a tiny bit lower than some Android phones in one test, it suddenly has a 'far inferior' camera. Then there's the RAM, curved screens and so many other things I could mention, but my point is that I think Android users can't recognize a genuine game-changing feature-list because they're so used to getting bombarded by tons of arguably useless high spec lists and gimmicks that are marketed as 'the next big thing'.
It's almost as if Google took over the reality distortion field from Apple. Just wait a couple of years when all Android devices have 'Android sense' (or something) displays (3D touch), THEN it will be a game changing feature because they'll have 1000's of pressure levels they can sense as compared to the 'useless' iPhone's (hypothetical) 128 levels.
Don't get me wrong here, I'm not trying to bash Android or people who choose to use it, I just don't like those who post nonsense without anything to back it up just so they can sleep at night having convinced themselves that they bought the right phone. I've been a reader of this site for years and believe their test results to be correct, as they've always been. People who claim otherwise should come with facts or stop sprouting nonsense.
I, for one, agree with the review and think it's the phone with the best all round feature set on the market today. Is it perfect? Of course not, but it's a genuinely forward thinking and exceptional smartphone in a stale smartphone market, and that deserves that gold award in my book.
Thanks for the review!
Aritra Ghatak - Sunday, November 8, 2015 - link
As the reviewers pointed various aberration and distortions associated with using a brighter lens and that it is wise Apple went with the F 1/2.2 aperture lens. Could you please explain how Samsung manages with an F 1/1.9 aperture lens in Galaxy S6? Or for that matter the F 1/1.8 lens in LG G4 or Nokia Lumia 720/730?patamat - Sunday, November 8, 2015 - link
Well, we all know who Anand went to work for after writing few "balanced" reviews like this one.(apple ...)
Psymac - Monday, November 9, 2015 - link
Where is the phone function analysis of this iPhone?zimmybz - Tuesday, November 10, 2015 - link
I guess I'll try to build the bridge for the Droid guys here that are having a hard time.I haven't had an iPhone since the Galaxy S came out. Been a droid user since.
I recently got a 6S Plus. I sold a Note 5 and cancelled a pre-order for a Nexus 6P.
I will say it since nobody else will. The Note 5 has a great camera, S-Pen is cool, and enough RAM to keep multi-tasking running, but otherwise it's a shitty phone. The battery life and Touchwiz still leave a LOT to be desired. Build quality is great, but it suffers from what every other Droid phone suffers from - fractured, fragmented hardware eco-system and specs driven production. (Hang on)
If you need to know why you should cancel a 6P pre-order, look at the subreddit (Holy crap, lol.)
Anyways, in my first week with the 6S Plus, I hit 22% battery with 88 hours standy and 13 hours usage. That is completely insane.
Back to the Note 5 - look at the graphs on the review here. This phone absolutely DOMINATES the Note 5 across the board, a fact which I can confirm first hand.
I can also tell you that holding the phones side by side looking at the same picture taken on the Note 5, the displays are functionally indistinguishable from the other. (So much for all that resolution, I guess)
This is a large reason why the Note stutters against the 6S Plus. It's pushing a LOT of pixels that aren't really evident in day to day use, especially sitting next to the iPhone.
I guess I finally reached the point, I just want the best phone every year regardless of manufacturer or software.
Until Google makes it's own hardware in house and breaks free of QualComm, Apple is going to beat them every year going forward. I'm not 20 anymore, I don't care about a home screen widget. I want the battery not to drain from some stupid Google Play Services memory drain while the phone is sitting on my desk.
I don't want Samsung Services blowing up the battery either. And - NO - I should not have to root kit, Package Disable, Power Saver, Turn off Location, etc, etc, etc. I paid $1000 for a premium handset with lots of features.
Oddly enough, the iPhone can leave all that crap on and STILL get good battery life. The arguments for Android are shrinking right now. I'll never buy another Samsung phone again. I will miss the S-Pen, but Touchwiz is heinous, even in it's current iteration.
I would really love to see Google put up a fight in the premium handset market, but I don't think their hearts are in the hardware QUITE yet.
Anyways, happy 6S Plus user here, 4+ year droid convert at the moment. We'll see what next year brings.
zeeBomb - Wednesday, November 11, 2015 - link
Ss or bs (sorry I just had to)JTRCK - Friday, November 13, 2015 - link
I actually returned a 6S Plus for the Nexus 6P and the main reason was PRICE. They are as equally performant in day to day tasks, but the Nexus 6P had better multitasking performance for me due to the buttons and added power of a side launcher which is not possible on iPhone. I basically never have to go to the home screen again when using Google docs, searching the web, etc... I tried both out for about a week. The only feature I liked on the iPhone 6S Plus better was the cooler white colors of the LCD; other than that the Nexus 6P was better "for me" in every aspect. The phone "flies" in every sense of the word. No stutters, no lag, no unresponsiveness (typical of Samsungs). I have been an iPhone user since the 3GS. I also used the iPhone 6 Plus this year for 5 months.And I truthfully don't understand all this commotion over the new iPhone 6S Plus being the best phone ever released. Outside of "3D touch," there is not much difference in day to day performance or general use between both this year's model and last year's model. That is generally a great testament to iOS stability and performance. So much so that my old iPhone 4s opened apps faster, surfed faster, multitasked faster, etc, than my now defunct Note 4. Apple has been on top of their game for years, IDK why android fans have only now noticed. But iOS is truly very limited. You will sooner or later find out the gates keep you truly locked in.
But the main factor for me, again, was price. I do not in any way find the iPhone to be a better phone than the Nexus 6P. In fact, I find its system to be inferior in a multitude of ways. Is the iPhone Better than the Note 5 and all its clumsy and useless features? Yes. But the Nexus 6P is in a category all its own. Especially for $650. That is exactly what I paid for the 128GB model compared to the $1,170 I paid for the iPhone 6S Plus.
astroboy888 - Wednesday, November 11, 2015 - link
"FinFET transistors are necessary because as transistors get smaller their leakage (wasted power) goes up, and without FinFETs leakage would spiral out of control. In fact that’s exactly what happened on the 20nm nodes from Samsung and TSMC; both companies thought the leakage of planar transistors could be adequately controlled at 20nm, only for leakage to be a bigger problem than they expected"It is not they "discovered" 20nm leakage was high; therefore they switched to 16nm FinFet. This is an incorrect comment.
FinFet transistors structure had been on the road map and in development at TSMC for more than 10 years. TSMC's first finfet transistor was demonstrated in 2002 when the inventor Professor Chen-Ming Hu of UC Berkeley was working at TSMC as CTO. Therefore Finfet process had always been on the roadmap for 16nm process. The 20nm planar process had always been on the road map as a planar process. Every process node takes about 3-5 years to develop, so the customers (semiconductor chip designers) signs up 3-5 years before hand to co-work with TSMC to design a chip for that process. These were communicated ahead of time and contracts where signed.
In the late 1990s and early 2000s, the semiconductor industry was pushing for SOI (Silicon On Insulator such as GaAs "Gallium Arsenide), which completely eliminates leakage current. But the transistor performance turned out to be too unpredictable and too expensive to manufacture. Therefor the industry stuck with silicon, until FinFet structure was invented in 2000 and manufacturing process perfected some 10 years later.
gonsolo - Thursday, November 12, 2015 - link
If I may suggest something: I'd like to see app startup times as a benchmark from iPhone 5 onwards. This is something I'm doing a lot; waiting for apps to start.