How it Works: Systems on a Chip (SoC)

June 8, 2012
110
41 35 34

HOW-IT-WORKS system on a chip

When buying smartphones and tablets, we often talk about their processing power, and make a big fuss of their speed, and whether they can offer single-, dual-, or multiple-core capabilities. And while we do focus on the processor most of the time, you’ll have to know that things aren’t as simple as that. Instead of just simple processors, we have Systems on a Chip (SoC) inside these devices that offer more complex functionality.

What is a System on a Chip?

Since smartphones and tablets are basically smaller computers, they require pretty much the same components we see in desktops and laptops in order to offer us all the amazing things they can do (apps, music and video playing, 3D gaming support, advanced wireless features, etc).

But smartphones and tablets do not offer the same amount of internal space as desktops and laptops for the various components needed such as the logic board, the processor, the RAM, the graphics card, and others. That means these internal parts need to be as small as possible, so that device manufacturers can use the remaining space to fit the device with a long-lasting battery life.

Thanks to the wonders of miniaturization, SoC manufacturers, like Qualcomm, Nvidia or Texas Instruments, can place some of those components on a single chip, the System on a Chip that powers your beloved smartphone.

What’s inside of a SoC?

Now that we know what a SoC is, let’s take a quick look at the components that can be found inside it. Mind you, not all the following parts are built in all the different SoCs that we’re going to show you later on, but in order to better understand how a SoC works, you should have a general picture of what goes inside it:

  • CPU – the central processing unit, whether it’s single- or multiple-core, this is what makes everything possible on your smartphone. Most processors found inside the SoCs that we’re going to look at will be based on ARM technology, but more on that later
  • Memory – just like in a computer, memory is required to perform the various tasks smartphone and tablets are capable of, and therefore SoCs come with various memory architectures on board
  • GPU – the graphic processing unit is also an important component on the SoC, and it’s responsible for handling those complex 3D games on the smartphone or tablets. As you can expect, there are various GPU architectures available out there, and we’re going to further detail them in what follows
  • Northbridge – this is a component that handles communications between the CPU and other components of the SoC including the southbridge
  • Southbrige – a second chipset usually found on computers that handles various I/O functions. In some cases the southbridge can be found on the SoC
  • Cellular radios – some SoCs also come with certain modems on board that are needed by mobile operators. Such is the case with the Snapdragon S4 from Qualcomm, which has an embedded LTE modem on board responsible for 4G LTE connectivity
  • Other radios – some SoCs may also have other components responsible for other types of connectivity, including Wi-Fi, GPS/GLONASS or Bluetooth. Again, the S4 is a good example in this regard.
  • Other circuitry

ARM vs x86 CPU Architecture

Throughout this article you will see us mention the ARM technology more than once, since the SoCs used by current Android smartphones and tablets are built using this ARM architecture. So what is ARM exactly? MaximumPC shares some details regarding the early days of ARM:

In the beginning, the ARM architecture was specifically developed for use in a PC—the Acorn Archimedes to be precise. In 1987, the Archimedes hit the market, powered by the ARM2 processor with up to 4MB of RAM and a 20MB hard drive. With only 30,000 transistors (less than half of the Motorola 68000’s 68,000), the ARM2 was one of the simplest 32-bit processors of its time. This lower transistor count, paired with the efficient reduced instruction set computer (RISC) architecture, allowed ARM2 to outperform Intel’s 80286 while consuming less electricity.

What’s important to remember is that ARM is still the preferred choice by SoC manufacturers, as the architecture ensures high performance at low power, which is what customers are unconsciously interested in.

The Intel 8086 CPU launched in 1978 was a 16-bit microprocessor that was followed by several successors whose names also ended in “86.” Thus, the x86 term was coined. Today the x86 architecture also includes 32-bit CPUs, which can be found in various computers that you may be using on a daily basis. The disadvantage of x86 architecture in mobile SoC is that they’re not as power efficient as ARM-based CPU. Only Intel currently develops an x86-based SoC for mobile devices, the Atom Medfield platform.

GPU architectures

The SoCs that we’re going to describe below use various GPU technologies coming from various companies. You’ll see GeForce, Adreno, ARM Mali, or PowerVR get mentioned a few times so here’s what these names mean:

  • GeForce – produced by NVIDIA, these are the ultra low power graphics cards found on Tegra 3 SoC
  • Adreno – produced by Qualcomm, the Adreno GPUs are part of the Snapdragon SoC made by the same company. Some Adreno GPUs can also be used on future Microsoft Windows 8 devices.
  • ARM Mali – as you may have guessed, Mali GPUs are designed by ARM and they’re currently used on various SoC designs including Exynos and NovaThor
  • PowerVR – PowerVR is a leading GPU designers, whose GPUs are found on various SoCs including Medfield, NovaThor (future designs), OMAP, and even Apple Ax.

SoC varieties

There are various SoCs out there, from different manufacturers that equip Android devices, from smartphones to tablets, but they’re not completely similar. Let’s take a look at some of the most important ones for you.

NVIDIA Tegra 3

Also known as Kal-El, the NVIDIA Tegra 3 series is one of the SoC sub-families of the Tegra family and it’s currently employed by various Android devices, including, but not limited to, the Asus Eee Pad Transformer Pad, HTC One X (international version), the Asus Transformer Pad 300, the LG Optimus 4X HD and others. The rumored Google Nexus tablet will also reportedly come with a Tegra 3 SoC on board.

Tegra 3 comes with a quad-core CPU, but what’s interesting about it is that it actually has five cores. The design is meant to optimize power consumption in various device activity states and extend battery life. Each core is a Cortex A9 ARM chip, but the fifth one, which is made of a special low power silicon process, is limited to an optimal speed of 500MHz. This is because it will handle only certain tasks, and only in certain situations. The companion core will be used by the device when in standby mode or when dealing with certain tasks that don’t require faster processing. When the device is switched on (or better said in use), the other cores come to life and users can enjoy a great smartphone and tablet experience, with great graphics and processing speed.

In addition to the CPU, the Tegra 3 SoC also contains the graphics processing unit (GPU), northbrige, southbridge, and memory controller. The SoC supports video output up to 2560 x 1600 resolution and 1080p H.264/MPEG-4 AVC video codec (recording and playing high quality videos).

Qualcomm Snapdragon S4

Qualcomm is another important name when it comes to Android smartphones and tablets (but not only) as the American company is responsible for various families of SoCs used in various generations of smartphones and tablets. Since Snapdragon S4 is the Qualcomm SoC used by some of the most recent devices out there, we’re going to focus on it, but you’ll have to know that the S4 was preceded by other SoC generations.

Snapdragon S4 has a processor that’s similar to the ARM Cortex-A15 CPU, but built according to Qualcomm’s own design. In addition to the CPU, the Snapdragon S4 offers HD video recording and playing support and integrated Adreno GPU capabilities. But one of the most interesting things about the S4 is that it also packs a modem with radio capabilities required by smartphones and tablets with cellular circuitry.

Specifically, the S4 packs a 4G LTE modem, which explains why various companies launched their high-end devices with quad-core capabilities in international markets (using various SoC solutions other than the S4), but when it came to the U.S. launch, they replaced them with the S4 to offer 4G LTE support, even though it only packs dual-core processing powers. The S4 also handles Wi-Fi, GPS/GLONASS, and Bluetooth on most devices.

There are various Snapdragon S4 SoC versions, built on both 40nm and 28nm technology (lower is better as it’s more power efficient) and they are used in some Android devices you may have already heard of, including the HTC One S, Asus Transformer Pad Infinity, North-American HTC One X, HTC EVO 4G LTE, Sony Xperia S, North American Samsung Galaxy S3, and others.

Samsung Exynos 4 Quad

As you’d expect, Samsung has its own SoC platform, the Exynos family. Of those SoCs, we’re going to focus on its latest addition, the Exynos 4 Quad, that’s found on the international version of its 2012 flagship smartphone, the Samsung Galaxy S3.

Exynos SoCs are also based on ARM architecture, just like Tegra 3 and Snapdragon S4. The Exynos 4 Quad is built with 32nm High-K Metal Gate (HKMG) process that’s ready to offer “twice better CPU performance” but 20% lower power consumption than the previous model, which was used in the Galaxy S II. Exynos 4 Quad packs a 1.4GHZ Quad-core ARM Cortex-A9 CPU and the ARM Mali-400 MP4 quad-core GPU. The processor supports 3D gaming, fast multitasking and HD video recording and playback. The Exynos 4 Quad is used in the Galaxy S3 (international version) and in the Meizu MX Quad.

Previous Exynos generations can be found in the Galaxy S2, Galaxy Note, Galaxy Tab 7.7, Galaxy Tab 7.0 Plus, Galaxy S, Droid Charge, Exibit 4G, Infuse 4G, but also in non-Samsung devices such as the Meizu MX and Meizu M9.

Intel Medfield

While you’re likely to find various Intel processors in all sorts of desktops, laptops and notebooks, the company has not really made a play for the mobile business until earlier this year. Intel announced at CES 2012 that it plans to attack the smartphone and tablet mobile business with its own SoC platform, codenamed Medfield, which should be found inside various mobile devices in the future.

So far, we have three such devices announced, the Orange San Diego (Santa Clara) the Lenovo K800, and the Lava Xolo X900. Intel announced a partnership with Motorola (owned by Google) and we’re certainly curious to see the first Googlerola devices to come with Intel circuitry on board.

Medfield SoCs are built with 32nm HKMG technology, just like the Exynos Quad 4 Core but it’s not based on ARM architecture. Instead, Intel is relying on its own x86 technology to make these SoCs. Medfield SoCs can offer OEMs a 1.6-2GHz single-core processor and PowerVR’s SGX540 GPU.

Texas Instruments OMAP 4

While they’re not as popular as Qualcomm or NVIDIA SoCs, the OMAP family from Texas Instruments should definitely be taken very seriously. In case OMAP sounds familiar, that’s because we’ve seen such SoCs equip various Android devices in the past, including the original Motorola Droid that spawned the Android revolution, the Barnes & Noble Nook Color and Nook Simple, the Motorola Bravo, the Motorola Defy, the LG Optimus Black, the Motorola Droid 2, the Samsung Galaxy S LCD, but also non-Android devices like the Palm Pre and Pre 2 or the Nokia N9.

The latest TI OMAP SoCs family is the fourth-generation OMAPs, or OMAP 4, which relies on a dual-core ARM Cortex-A9 45nm-based architecture. There are various OMAP4 SoCs, but all of them will offer PowerVR graphics. The OMAP 4 4470 model stands out because, in addition to the dual-core CPU, it has two companion Cortex-M3 cores that are supposed to take over smaller tasks to increase power efficiency, just like the fifth core found on the Tegra 3. The 4470 model also comes with 1080p full HD video recording and playback support.

Here are some Android devices that pack TI OMAP 4 SoCs: Motorola Atrix 2, Motorola Droid 3, Motorola Droid Bionic, Motorola Droid RAZR, Motorola Xyboard, some Samsung Galaxy S2 models, Amazon Kindle Fire, Barnes & Noble Nook Tablet, Samsung Galaxy Tab 2 7.0, Samsung Galaxy Tab 2 10.1, Samsung Galaxy Nexus, LG Optimus 3D and LG Optimus Max. But an OMAP 4 SoC can also be found on the BlackBerry PlayBook for example.

ST-Ericsson NovaThor

The NovaThor SoC platform developed by ST-Ericsson is not that known in the mobile business, although we already have certain devices that rely on this SoC including the Sony Xperia P, Sony Xperia U, Sony Xperia Sola, Samsung Galaxy Ace 2, Samsung Galaxy Beam and the HTC Sensation for China. The NovaThor SoCs used so far come with 1GHz or 1.2GHz dual-core ARM Cortex-A9 processors, single core ARM Mali 400 GPUs, and wireless support (GSM/EDGE/HSPA/HSPA+, depending on the model used.) Current NovaThor SoCs are built on 45nm process technology, although ST-Ericsson plans to launch more power-efficient models that will come with 32nm/28 semiconductor technology and that will feature faster CPU speeds, Power VR graphics and even LTE support.

Other SoCs

We couldn’t talk about Systems on a Chip without mentioning what the competition is using. Apple has its proprietary line of AX chips (A4, A5 and A5X), which have been used on all of its iOS devices starting with the original iPad. The flagship Apple SoC is the A5X, which currently equips the new iPad, but Apple is rumored to be working on a new model, the A6, that’s going to be found on board of future iOS devices.

Which one is best for me?

The obvious question you may have is, which of the SoCs above is best for me? .

In case you’re buying one of the last-gen Android tablets and smartphones available out there, which will surely pack one of the SoCs mentioned above, then you’re likely to get a similar performance across the board. Sure, every SoC manufacturer will defend its own brand with words like “power efficiency,” “high performance,” “3D graphics,” “full HD video,” but all these competing platforms will offer overall enjoyable user experiences with few differences between them. The fact remains that you shouldn’t buy a new device after looking only at SoC capabilities, but you should consider more factors like display technology, wireless connectivity, camera performance, and storage, in order to make a more informed purchase.

One such example is the American Galaxy S3 which packs a dual-core processor, part of the Snapdragon S4 SoC, instead of the quad-core processor that’s found on the Exynos 4 Quad SoC. This is because the American Galaxy S3 is supposed to offer LTE support, and it’s the S4 SoC that happens to have an LTE modem included, not the Exynos 4 Quad. So while some Galaxy S3 buyers will complain about not getting the full quad-core power promised by the international Galaxy S3 version, they still get that precious LTE support, in a (hopefully) power-efficient manner.

In case you want to buy a new/second-hand older Android device, then you should pay attention to its SoC and its capabilities, and check out performance comparisons (benchmark tests) to see how your chosen device fares against other devices.

And let’s not forget that all companies mentioned above are already working on next-gen SoCs, and we can’t wait to see what next year’s smartphones and tablets will be able to do thanks to new internal components and improved operating systems.

Comments

Load More