ST-Ericsson 28nm FD-SOI/ARM Chip Hits 2.8GHz at CES

Key technology behind world’s fastest and lowest-power integrated LTE smartphone platform


Posted by Adele Hars, Editor-in-Chief, Advanced Substrate News

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What a great start to 2013: at CES in Las Vegas, ST-Ericsson announced the NovaThor™ L8580 ModAp, “the world’s fastest and lowest-power integrated LTE smartphone platform.” This is the one that’s on STMicroelectronics’ 28nm FD-SOI, with sampling set for Q1 2013.

And it’s a game changer – for users, for designers, for foundries, and for bean counters.  Here’s why.

The NovaThor L8580 integrates an eQuad 2.5GHz processor based on the ARM Cortex-A9, an Imagination PowerVR™ SGX544 GPU running at 600Mhz and an advanced multimode LTE modem on a single 28nm FD-SOI die.

ST-Ericsson’s NovaThor(TM) L8580 on ST’s 28nm FD-SOI features a 2.5Ghz eQuad(TM) app processor with ultra-low power consumption. (Courtesy: ST-Ericsson)

In the eQuad CPU architecture, each processor core can operate as a high-performance core or a very-low-power core, depending on what’s needed at the moment. Since all the eQuad cores can adapt to the needs of the user at any given time, there’s no need for the dedicated low-power cores found in other multi-core CPU architectures. Remember, the 2.5GHz cores in the L8580 are the mobile industry’s fastest, or conversely, at 0.6V in low-power mode, the industry’s most battery-friendly. With all 2.5GHz cores working together, expect blazing high-performance when you’re doing something like browsing the web. But when phone’s your pocket, those cores will take barely a sip of power.

The NovaThor L8580 is essentially a straight port from 28nm bulk to 28nm FD-SOI of the (very successful) NovaThor L8540, with just a bit of tweaking to fully leverage cool things you can do with FD-SOI, like biasing to increase performance and conserve power.

For the folks designing smartphones and tablets (and ultimately for the end-user), that port to FD-SOI gets the NovaThor L8580:

  • CPUs running 35% faster and GPU and multimedia accelerators running 20% faster. In terms of multimedia performance, they’re supporting 1080p video encoding and playback at up to 60 frames per second, 1080p 3D camcorder functionality, displays up to WUXGA (1920×1200) at 60 frames per second and cameras up to 20 megapixels. (Hence their use of the descriptive “extraordinary”.)
  • 25% less power consumption than rival architectures when running at high-performance  levels – think Cooler Operation.
  • A low-power mode can deliver up to 5000 DMIPS at 0.6V – more than enough computing power for the majority of applications in everyday use. A key point here is that it enables stable SRAM operation at 0.6V – have you heard of anyone matching this? The result is that this low-power mode consumes 50% less power to deliver the same performance compared with alternative solutions in bulk CMOS.

It all adds up to big battery savings – this is the extra day CEO Didier Lamouche promised us in Barcelona last year when they announced this chip.

ST-Ericsson has posted an amazing video, filmed live at CES 13. In the first part of the demo (re: high-perf), on a Samsung Galaxy S3, they’ve got the Sky Castle 3D Graphics Demo launching twice as fast on FD-SOI as the bulk equivalent, and hitting 2.8GHz! And in the second demo (re: low power), they’re hitting 1GHz using just 0.636V, which would take 1.1V on bulk.

Design Highlights

For the ST-E designers, most of the IP blocks were directly re-used from the bulk design, so the porting to FD-SOI was extremely simple and fast.

For the manufacturing folks over at STMicroelectronics (and starting this year, at GloFo), FD-SOI is a planar technology that re-uses 90% of the process steps used in 28nm bulk. The overall manufacturing process in FD-SOI is 12% less complex, so they’ve got lower cycle time and reduced manufacturing costs (bean counters take note, please). They also point out that the manufacturing tools for FD-SOI are much simpler than those required for FinFETs.

Wondering what’s next? The 14nm FD-SOI node is already in development, the ARM Cortex-A15‘s  on the radar, and the FD-SOI roadmap is already defined up the 10nm node.

With FD-SOI, you can do much more with body-biasing (aka back-biasing) than you can in bulk (which suffers from too much leakage). Thanks to the ultra-thin insulator layer in FD-SOI, the biasing creates a buried gate below the channel, so it effectively acts like a vertical double gate transistor. This facilitates the flow of electrons, leading to a higher voltage in the body, and faster switching of the transistor. (Image courtesy ST-Ericsson)

With FD-SOI, you can hit higher speeds with lower operating voltages. This is because the buried oxide layer prevents electrons from leaking away as they travel through the channel from the source to the drain (this sort of leakage is a major source of power consumption in 28nm bulk, which depends on doping to handle leakage). Interestingly, this graph shows ST-E going down to 0.5V – which is incredibly impressive. (Image courtesy of ST-Ericsson)

(Image courtesy ST-Ericsson)

(Image courtesy ST-Ericsson)

As the (now award-winning) folks over at ST and Leti described for us a few years ago, designing a good SOC involves using the right blend of low, standard and high-Vt devices according to the target application and how it’s being used at any given time.  The ST-E designers use this feature to apply different voltages independently to the top and the buried gates of the FD-SOI transistor, which effectively changes its characteristics. By choosing optimal combinations of the voltages, the transistor characteristics can be transformed from those of a very high-performance transistor to those of a very low-power transistor. A processing core built up of such transistors can operate as if it were in fact two cores – one optimized for high performance and the other for low power. (You can’t do this with FinFETs, btw.)

Just Posted: FD-SOI video & white paper

Just as this blog was going online, ST-Ericsson posted an excellent, in-depth white paper; and in partnership with STMicroelectroics, a YouTube video detailing the how’s and why’s of FD-SOI.Here are the links — you really don’t want to miss these:

Multiprocessing in Mobile Platforms: the Marketing and the Reality
In this white paper, ST-Ericsson’s Marco Cornero and Andreas Anyuru “…illustrate and compare the main technological options available in multiprocessing for mobile platforms, highlighting the synergies between multiprocessing and the disruptive FD-SOI silicon technology used in the upcoming ST-Ericsson products.”

An Introduction to FD-SOI
STMicroelectronics and ST-Ericsson have teamed up on this excellent video, which garnered 1250 views within the first four days of its posting on YouTube. The animations and comparisons highlight why FD-SOI is so fast, and so cool.

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