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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ciderrules - Tuesday, November 3, 2015 - link
You think long press is OK? Imagine if right clicking in Windows you had to hold the right mouse button down for a second before the context menu popped up. You think people would accept that? 3D Touch is literally right click. It's faster than that stupid long press and leaves long press for other less used options.Note 5 is inferior to the iPhone 6S Plus. In almost every way, except the screen. And the screen is not nearly as big an advantage as you try to make it out to be. Sound like someone is upset at their choice of purchase.
MattL - Tuesday, November 3, 2015 - link
@ciderrulesYour tone reveals your bias.
Long press is fine, you can have a long press that's as low as 500 ms or so, maybe even less... Pressure sensitive touch (I refuse to call it 3D touch lol) might be a slight bit faster, maybe more efficient, we'll see... but the truth is that a lot of the functionality that was added could have easily been done with a long press, right now people are seeing the contrast of going from no long-press like context specific functionality straight into pressure sensitive context menus, so it seems extremely improved because they skipped an entire step they could have done long ago.
You assume too much about me lol, I don't own a Note 5, I own a Note 4. I didn't see a reason to pay to upgrade to the Note 5, it's an incremental upgrade, worth getting for new users but not enough to rush to upgrade. I have owned an iPhone in the past, so I'm plenty familiar with Android and iOS... I love my Note 4 and don't see any reason to upgrade to either Note 5 or iPhone 6s Plus.
The iPhone 6s Plus is not superior in every way except the screen lol. The screen is very likely to be superior on the Note 5 (since Samsung has put out far superior screens for multiple generations now) though I'll hold off on the Display Mate review which does a *far* deeper analysis than Anandtech on screen. Areas where Anandtech makes offhand commments about viewing angle quality etc Displaymate will release hard numbers, such as how much brightness decreases at an angle, contrast loss, etc.
Don't downplay the advantage of screen quality in the Samsung phones over the iPhones though, they offer a *Far* superior contrast which often is considered the most important image quality aspect. They usually offer somewhat superior color accuracy though they both are getting so close to perfect they both are usually beyond (or close to beyond) what the human I can see. Keep in mind that the Samsung phones offer a mode that is calibrated and supports the Adobe color gamut, something that is very impressive on a mobile device (and for professionals is actually very useful). Also viewing angles are often far superior on the latest Samsung screens, especially in brightness and contrast (where you see a significant benefit).
All these things add up quite a bit and considering the screen is your primary interface input for your phone it shouldn't be underplayed... Honestly far more important than CPU and GPU speeds in my opinion (why I mostly stopped caring about CPU and GPU specs a couple years ago, though from a technical perspective it's interesting).
These are all things you should educate yourself on before you make assumption based comments about another persons intentions.
I am impressed with Apples progress on the CPU and GPU side... Storage (to a lesser extent since let's be honest PCIe storage was inevitable to come to phones, just like NFC payments came to Android phones first Apple hit this mark a bit early, credit given in context) is also a good improvement. Apple users have long argued they don't care about specs like that though ironically and honestly I've agreed with them for at least 2 years now (when I felt phones reached a certain level of power where they get diminished returns beyond that, unless some drastic new feature is discovered that needs serious more power, say maybe MS continuum where it needs to run as a desktop).
I'm just a proponent of a fair review, the distinct advantages of the Note 5 and Edge phones are heavily underplayed in this comparison while the advantages to the latest iPhone is heavily emphasized... Not only that Anandtech mentions two out of three negatives to the Samsung display aren't even mentioned in their Samsung review (and something I don't find mention of in other in-depth display reviews) so either they didn't feel the need to point it out when they actually reviewed the product or they felt the need to speculate or invent new negatives to make it look more balanced.
Comparisons are pointless unless they are fair.
MattL - Tuesday, November 3, 2015 - link
Also to add, one area where the latest Samsung phones excel (and other Android phones actually) is camera quality. Refer to the dxomark analysis where the iPhone's latest camera is literally a wash compared to it's last gen tech... while Android cameras (that were already better than last gen iPhone) have taken a further step up.Ironically it's a reverse of what you see with the SoC, where Apple took a big step forward while Android SoC languished a bit (though again to be fair it's 6 months older, but still it wasn't a bit step forward) while the iPhone camera performance literally was overall equal to last gen (a baby step forward in some areas and backward in others) while Android continues to use camera tech that progresses nicely forward.
osxandwindows - Tuesday, November 3, 2015 - link
Personally I like the iPhone camera better.I have a note 5 and iPhone.
Some people think DXO marc were paid.
Many people like the iPhone camera better tho.
The note 5 has a grate camera.
Heck people didn't like the sony z5 at all.
So on the camera side its completely your opinion.
Or should I say personal for a preference.
MattL - Friday, November 6, 2015 - link
But see it isn't your opinion lol. That's like saying the SoC is your opinion, which completely invalidates all the great work Anandtech did on reviewing every detail of that SoC.Now how the software uses that SoC (being the OS) comes somewhat down to opinion, do you like iOS vs Android etc.
Cameras are the same way, you can analyze the raw performance of a variety of aspects, especially the sensor. Now how you like the Camera app software, that can come down to preference or if there are trade-offs you might prefer trading one thing for another etc.
Also no one who has a clue thinks dxomark was paid off lol. They've been doing sensor analysis for a long time, before mobile phones were worth measuring they just did DSLR sensor analysis, including the top end professional grade cameras. They still do this and are still an oft referenced source not only by professionals and consumers but by other camera review sites around the web. Sensor and metric performance is just one aspects of a Camera of course, but they offer tangible and quantifiable metrics that can help you understand how cameras compare... and the latest gen of iPhones scored equal to the last gen, effectively no improvement, while the Android cameras keep leading the pack.
It's not surprising since the leading sensors on the Mobile list on dxomark are made by Sony which also has the leading sensors in professional grade DSLR and mirroless cameras as well. Sony has made best-in-class sensors (Nikkon has used sony sensors for many of their cameras for a while now) for a long time.
This is why anyone who has a clue just laughs at anyone questioning Dxomark or that a Sony sensor in a phone can be better than an Apple one.
Again there are more things to consider than raw performance, much like the iPhone's new superior SoC won't get you Android style widgets, a back button, or multi-tasking if you prefer those things... just like a new Android coming out with a faster SoC won't get you the iOS UI experience (if that's your preference)... but there are important metrics to evaluate and it feels like this review downplayed all the advantages of the other phones and overplayed the CPU and GPU advantage in the new iPhones. Some of us just think that's a bit biased.
ciderrules - Tuesday, November 3, 2015 - link
Something clearly bothers you to spend so much time typing a response.osxandwindows - Wednesday, November 4, 2015 - link
Naw man just felt like doing it.FL777 - Friday, November 6, 2015 - link
Great comment, I thought that the authors "fell in love" with the efficiency that Apple built into its new SoC. Being computer lovers, it is somewhat foregivable. However, they do appear to be school children saying, "Wow, this bright shiny SoC is the best damn thing in the whole wide world."Hands down, the Note 5 and Galaxy S6 at the very least compete with the iPhone 6S and in my mind, they are better phones for a number of reasons.
FL777 - Tuesday, November 3, 2015 - link
First let me compliment the authors of this article. No other website anywhere does as thorough a job as Anandtech in objectively reviewing a smartphone. You provide solid, objective facts for your reviews. That is something most reviewers utterly fail at. That being said I have some criticisms:1. The iPhone 6S display is just sad compared to the Ssamung S6 and Note 5
2. 3D Touch has been listed as buggy in other reviews and yet you don't mention this issue
3. The Note 5 and Samsung S6 BOTH charge much more quickly than the iPhone 6S. That is VERY IMPORTANT IN THE REAL WORLD
4. Both the Note 5 and the S6 have wireless charging, which is very convenient. The Note 5 has quick wirless charging which is revolutionary - no other phone has it.
5. The Samsung S6 and Note 5 SoC is effectively about 7 months older thatn the iPhone 6S SoC. I hope you will be as complimentary to the Galaxy S7 SoC when it comes out in January. It is supposed to be 25% faster than the 6S SoC. The new Samsung SoC is rumored to be a beast.
6. Also upcoming with the Galaxy S7 is alwo rumored (and this is just a rumor) to have its own 3D touch.
7. While the iPhone 6S is faster than the Note 5 and Galaxy S6, is there really that much difference in the real world? I think you have lost your objectivity because youa re impressed with Apple's SoC. And remember, the huge gains the IPhone 6S would not really be possible with Samsung's and TMCS's chip manufacturing skills. Apple should be concerned with Samsung's advent of manufacturing its own SoC chips - by all accounts, the Exnyos 7420 is a brilliant SoC and it STILL competes with the iPhone 6S, though it is nearly eight months older.
8. MANY professional reviewers including some professional photographer reviewers have stated that the S6 camera, the Note 5 camera and the LG4 camera are all better than the iPhone 6S camera. One rason is that they can take RAW photographs and have full manual control. Again, it appears that you have lost your objectivity when reviewing the camera functions.
9. I own the Galaxy S6 and one of my friends that I dance with has the iPhone 6S and you are INCREDIBLY wrong in your conclusions for low-light situations. At our dances, my friend's iPhone 6S is UNUSABLE, the sensor simply doesn't let enough light in My Samsung S6 has become the goto phone to take ALL of the crtical videos and pictures when we dance. One of my other friends owns an iPhone 6 and he can't use his phone at our dances. He borrowed my phone to vidoe his friend last week when his friend was dancing with a famous champion.
Simply said, you couldn't be more in error about the low-light capabliities of the two phones. Frankly the iPhone 6S is embarrassing in really dark situations.
I agree that the iPhone 6S and the Galaxy S6 / Note 5 are the two best phones on the market right now. Where we disagree is that the iPhone 6S is that much better than the Note 5 and S6. The display issue itself is embarrassing. The iPhone doesn't even have an HD screen. The 6S is the fastest smartphone on the planet right now, but so what????? It is only a microsecond faster than Samsung's last generation phones and most people won't care. Applies IOS is superior in its cohesiveness, Android is catching up quickly.
blackcrayon - Tuesday, November 3, 2015 - link
The display issue is far from "embarrassing". What's embarrassing is having a display that taxes your GPU to the point that you can't maintain top level performance over the course of an intense 3D graphics session. I'll take performance over more pixels any day, the small observable difference is a terrible tradeoff some of the manufacturers are making just to post a larger number on a spec sheet.