Inside Apple’s A7: dual-core CPU, quad-core GPU, Secure Enclave has 3MB SRAM

By , Sep 27, 2013

A7 floorplan (Chipworks 001)

Following their initial analysis of the iPhone 5s’s innards, silicon experts at Chipworks have now taken a closer look at the handset’s 64-bit A7 processor to reveal a number of interesting tidbits in their initial low-level chip analysis. Based on transistor-level images of the Apple-designed, Samsung-built package, Chipworks was able to determine that the A7 consists of a dual-core processing core and quad-core graphics, tentatively identified as the four cluster version of Imagination Technologies’s PowerVR Series 6, the G6430.

Apple, along with Intel, is of course an investor with a ten percent stake in Imagination Technologies, the UK-based fabless semiconductor maker. Chipworks also focused on a portion of the A7 chip called Secure Enclave where Apple says fingerprint profile is stored securely and walled off from the entire system, except the Touch ID circuitry…

As can be seen on the transistor-level shot top of post, the A7 is a so-called system-on-a-chip, a design that combines pretty much everything a mobile device needs on a single piece of silicon: from CPU/GPU cores to shared logic, memory and other interfaces, RAM, cache, controllers and more.

Although it’s yet to perform a real circuit extraction to confirm the findings, Chipworks preliminarily concluded that the dual-core CPU is Apple’s own design based on the ARMv8 architecture, not the licensed ARM A53/57 design.

The CPU core likely incorporates 256KB of L1 cache and 1MB of L2 cache. They have not determined whether the A7 packs in 1GB of RAM or more. Note that four GPU cores is a step up from the three-core GPU inside the iPhone 5′s A6 processor.

The chip itself is thought to be fabbed on Samsung’s advanced 28-nanometer Hi K metal Gate, which is the same process technology Samsung employs for its own Galaxy S4 Exynos processor.

The dual-core CPU and cache make up ~17 percent of the die area, and the quad-core GPU and shared logic about 22 percent.

As for the chip’s Secure Enclave, Chipworks explains:

Actually, if we compare it with the A6, that may not be such a stupid idea – there is no comparable block that I can see in there.

I wouldn’t have thought that a fingerprint scan would create that much data, but given that multiple scans have to be stored, and in any orientation, maybe that much storage is needed.

One thing we do know is that it’s the biggest fingerprint sensor that we’ve seen so far, coming in at ~39 mm².

Secure Enclave is part of the A7 chip, as depicted on the screenshot below grabbed from Apple’s promo vid.

Apple A7 chip (Secure Enclave 001)

Chipworks estimates that Secure Enclave is basically a huge block of SRAM with at least 3MB of storage capacity. It’s found right above the GPU cluster.

The A7 also shares a few design similarities with its predecessors, the A5, A6 and A6X, such as the USB, LCD and camera interfaces. Chipworks will be taking apart the Touch ID sensor and posting their observations in another post and I’ll make sure to keep you in the loop.

I’m curious about Apple’s design and engineering approach to AuthenTec-built Touch ID. For the time being, Touch ID is the most advanced, reliable and seamless fingerprint sensor on any device.

A6 floorplan (Chipwroks 001)

Yesterday, I analyzed Samsung’s biometrics efforts to conclude that the Galaxy maker is at least a year away from implementing fingerprint scanning on its smartphones.

“We are not yet developing the technology,” a Samsung official told The Korea Herald.

In its previous analysis of the flagship iPhone 5s, Chipworks has identified a number of design wins. The A7 processor is still being manufactured by Samsung, while the M7 motion coprocessor is basically a rebranded NXP LPC18A1 unit.

The handset’s back-facing iSight camera uses Sony’s Exmor-RS sensor, the front-facing FaceTime shooter is from OmniVision and the accelerometer is made by Bosch.

Pictured above, for comparison’s sake: the A6 floorplan.

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  • omrishtam

    so small yet so powerful…

    • rememberme

      ist truely amazing

  • Maxim∑

    where is the co-processor?

    • Beta382

      Separate chip. Take a look at the iFixIt teardown.

      • Maxim∑

        oh ok, I thought it would be inside the A7 but isolated, thanks

    • http://www.idownloadblog.com/author/dujkan Christian Zibreg

      The M7 is a separate chip

  • Meiklejohn Brandon

    How do they get those pictures?

    • http://www.iDoiDevices.com/ Jason Yeaman

      By cross sectioning the die then radiate it with electromagnetic energy. Tools usually used for non-destructive test/inspection.

  • vs511

    Anandtech had revealed most of this without opening the thing!

    • http://www.idownloadblog.com/author/dujkan Christian Zibreg

      Yes, though theirs was a speculative analysis. This is the real deal with real physical evidence.

      • vs511

        Yup, though, I’m saying just how accurate Anand was even without opening the 5s!

        Either way, the A7 is a beast, kicks Note 3′s processor’s butt (even though it’s clocked much higher; has more RAM; Quad-core)! The Note 3 is truly a waste of ‘specs’!

      • mehrab

        True! Android devices only perform good on paper and benchmarks this time they are losing at benchmarks also lol

  • Matt Taylor

    So we still don’t know how much ram this bad boy is packing!?

  • Gregory Kitchens

    i know it isnt very important, but does this article mention the clock speed? i skimmed it and didnt see it, read it a little slower and still didnt catch it. just wondering.

    • David Soto

      Same as A6 @ 1.3 GHz.

  • David Soto

    I love articles like these. They give me a tech bonner.