Monday, 2 January 2012

Mobile Phone Processors



The world “cellphone” is no longer unfamiliar to us. We know how much importance this little device has gained in our lives. When it comes to buying a cellphone, we fancy of owning the trendiest device available in market. We would hunt for a phone with highest camera megapixels, most stable operating system, and best of applications available. But, how many of us pay attention to the processor embedded inside the cellphone? In case you don’t know, processor is an intricate yet an integral part of a smartphone.

The processor inside a mobile phone is as important as the operating system it runs on. Because most of us are not aware of the tasks a processor performs, we tend to overlook it. A bunch of smartphones is already out there in market and some will be launched soon, so what will be your deciding factor while buying a mobile phone? What is it that makes one mobile phone better than the other? And answer is, the small processor present inside the phone. It is the processor that can turn your cellphone into a powerful device.

Snapdragon, ARM Cortex, Nvidia Tegra, are some common names when it comes to mobile phone CPUs. But, there's definitely more to explore about these processors and how one is more powerful or better than the other. Let's try to understand the nitty-gritty of the mobile CPUs.

System-on-Chip

Cell phones have a SoC (System-on-Chip), which is an integrated circuit consisting processor, memory blocks, GPU, and other peripherals. You cannot restrict yourself when it comes to exploring the world of mobile SoCs. Every processor manufacturer has its own philosophy when it comes to designing a chip.

ARM, is the leading name in designing and licensing processors for mobile devices. Companies like Samsung & Texas Instruments use the ARM architecture and ARM instruction set to design a compelling processor around it. Whereas, Qualcomm has gone out-of-league by following the ARM instruction set but designing a custom SoC named Snapdragon.

The ARM Architecture

ARM owns licenses for the technology that is behind SoCs. The company offers license of CPU architecture as well as ARM instructions that can be used in a processor of a mobile device. Most of the mobile phone manufacturers purchase ARM instructions and CPU architecture to build a SoC around it. Some modifications are also done to make the SoC meet device requirements.

Samsung and Texas Instruments for example have tweaked the ARM CPU architecture & instructions set for creating SoC for their smartphones. However, Qualcomm has only taken the ARM instructions and has built custom processor architecture for Snapdragon. The Scorpion processor of Qualcomm’s Snapdragon family uses ARMv7 instructions and is known for overpowering the limitations that Cortex-A8 has.

The 45nm & 65nm Manufacturing Technology

45nm & 65nm are sizes of the microscopic transistors that make up the CPU. Lesser the size of the transistor, more the number of transistors that can be fitted on the CPU board. There are various benefits of having smaller sized transistors:

  • More transistors can be fitted onto a chip, if their size is small. It means more implications can be made to the device.
  • Small transistors consume fewer watts and won’t get hot. It gives mobile device the ability to run at higher clock rate without draining-out the battery.

Number of CPU Cores

Number of cores in the CPU plays a crucial role in defining its performance. If your mobile phone has a dual-core processor, it will be faster than a single core processor phone because the work will be divided between both the cores. But, dual-core devices consume more battery.

Qualcomm Snapdragon

Snapdragon doesn’t use the ARM architecture and has designed core Scorpion processor based on ARMv7 instruction set with features similar to ARM Cortex-A8. The first generation of Snapdragon processor with 65nm transistors was embedded in Nexus One and HTC HD2. Snapdragon has now come-up with 45nm technology Snapdragon chips in HTC Desire HD, Thunderbolt. More transistors mean improved performance.

SoCs from Qualcomm come with GPS and cellular antennas. Since all the additional components are in one package, phones can be built more easily and will be sleeker.

Samsung Hummingbird

Samsung first debuted its Hummingbird processor in Galaxy S. It has 45nm ARM Cortex-A8 architecture, which makes it better than Cortex-A7 architecture based processors. Another USP of Hummingbird is the ARMNEON multimedia extension.

NEON technology accelerates the multimedia & signal processing algorithms in the Hummingbird processor. This result in improved video encoding/decoding, 2D/3D graphics, audio & speech processing, gaming, telephony, and image processing.Hummingbird has outclassed Snapdragon by rendering over 90 million triangles per second.

Nvidia Tegra 2

The second generation Tegra SoC from Nvidia is based on the dual-core ARM Cortex-A9 architecture. Since Cortex-A9 uses 40nm manufacturing technology, the density of transistor on the chip will be higher than A-8 based chips and it will result in enhanced performance plus low battery consumption. Nvidia has prefered sticking to ARMv7 instructions set in the Tegra 2 processor.

Nvidia has used it's custom designed GEForce Ultra Low Voltage (ULV) chip named 8 core GPU in Tegra 2 processor, which has following benefits:
  • Graphics performance is better than PowerVR SGX540 GPU (the one found in BlackBerry Playbook) performance.
  • The GEForce GPU supports HDMI output.

Motorola Atrix and Xoom tablet were the first few launches with Tegra 2 processor.

Apple A5

The SoC designed by Apple and manfuactured by Samsung, Apple A5 is based on ARM Cortex-A9 architecture & is a competitor of Tegra 2 processor. Minimum size of transistor is 45nm. The Apple A5 comes with NEON SIMD accelerator, which adds-on to the graphic performance of the mobile device. The CPU is said to be twice as powerful & GPU is seven times as powerful as its predecessor, Apple A4.

Conclusion

The competition is tough and it's going to get tougher in the near future. Qualcomm has adopted a different path by creating Snapdragon, a processor with an all new architecture but ARMv7 instruction set. It is said that Scorpion CPU has approximate 5% improvement in the per clock cycle ratio over the ARM Cortex-A8 based processors. One more reason for why manufacturers love Qualcomm is the integration of GPS & cellular network support in the SoC. This gives freedom to phone manufacturers to design a more compact phone or add additional features in the device.

Samsung hired a semiconductor company, Intrinsity to customize the ARM Cortex-A8 architecture in Hummingbird. The effort has resulted in 5-10% performance improvement in their CPU.

So, what are the thinks geeks are looking for in the future mobile SoCs?

  • It's time for SoC makers to switch to Cortex-A9 design architecture. Presented as the next-generation processor architecture, it can improve the device performance by up to 25%.
  • It is easily noticeable that transistor size results in significant improvement in terms of power efficiency & performance of device. We expect future processors to come with 45nm if not 28nm technology. The 45nm dual-core Snapdragon processor is said to consume 30% less power, which means that even a 1.5GHz SoC with 45nm technology draws the same amount of power consumed by 65nm 1GHz SoC.

Previous year was all about mobile phone operating systems and phone makers have done a great job. Gadgeteers are expecting 2012 to be the year of processors. Mobile processing unit makers are working hard to come-up with powerful devices that will have significant contribution in transforming the world of cellphones.

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