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from each compute node to its local DRAM but manages access to the system-wide memory resource. “Most importantly it can be implemented using available ARM technology with little additional hardware overhead,” Professor Goodacre said. Would you like chiplets with that? The project will make use of 64-bit ARM cores but makes the argument that at present levels of integration for servers chip costs are at the level $400 to $800 per unit and likely to double as production moves on to FinFET processes below the 20nm node. For reasons of yield the project sees a benefit in only implementing in leading-edge processes what needs to be and minimizing die size. These processor die become “chiplets” in the Euroserver nomenclature and sit on top of an interposer that carries peripheral circuitry. In the physical implementation each chiplet will be an octa-core Cortex-A53 part implemented in 28nm FDSOI. And four of these chiplets will go on top of an interposer in a packaged part. The Euroserver project started in September 2013 and for its first year has been working to flesh out and validate the computer architecture. One of the aspects of the architecture is to try and minimize use of long-distance interconnect and such bus standards as PCIe which were largely designed and optimized for performance rather than per-bit transferred energy consumption. “We’ve spent time looking at software access patterns and the communication between the islands of coherence. We can see how to achieve 100 nanoseconds compared with typical traditional figures of 500 microseconds,” said Professor Goodacre. Professor Goodacre said that the use of the ARM processor or the FDSOI process were not the most critical things in achieving a highly efficient and scalable architecture compared with the main thrust; how data is handled. However, having a low power processor on an intrinsically low power process all helps. How much does it cost? “Using ARM allows us to design a low-power system,” said Professor Goodacre. “And 28nm FDSOI gives us a very interesting power management lever with back biasing and retention modes. So it’s the FDSOI, the chiplets, the 3D stacking, the software that all together make the difference,” said Professor Goodacre. While European Commission funded projects are not supposed to be used as a means of subsidizing commercial operations, if it should spark European-based commercial success in datacenters at the expense of Intel’s x86 ecosystem few tears will be shed across Europe which has seen the strength and depth of its electronics base decline for many years. The total cost of the project is €12,925,771 (about US$15.6 million) of which European tax payers are expected to provide €8,599,929 (about US$10.4 million). MIT discovers superconductor law By R. Colin Johnson Superconductors are in the news again. This time, the Massachusetts Institute of Technology (MIT) has discovered a law governing thin-film superconductors, eliminating much of the trial and error for companies that manufacture superconducting photodetectors that can sense single photons and squids for super-accurate measurements of minute magnetic fields. Other applications that may benefit include the voltage standard chip used by the National Institute of Technology (NIST), the world’s first quantum computer from D-Wave Systems Inc., and numerous meteorology applications Ultra-thin superconducting film of niobium and nitrogen shows individual atoms, a view that helped MIT discover a universal law of superconductivity. (Image: MIT, Yachin Ivry) from Hypres Inc. “The applications for thin-film superconductors today are squids, photodetectors, voltage standards, metrology, and D-Wave’s quantum computer,” EE professor Karl Berggren told EE Times. He was assisted by Yachin Ivry, a postdoc in MIT’s Research Laboratory of Electronics. Today making thin-film superconductors involves a lot of trial and error, because there are no formulas that relate the different parameters. But with MIT’s new mathematical law, new superconducting chips can be designed with the correct parameters determined ahead of time with his and Ivry’s formula. “Understanding superconducting thin films makes designing them easier, when you know the relationship between critical temperature, resistivity, and film thickness,” Berggren said. Perhaps the most important parameter is “critical temperature” -- the temperature at which the material turns into a superconductor. Though that temperature can be optimized with MIT’s new formula, unfortunately, it cannot be reduced to room temperature with it. “We can optimize the critical temperature, but unfortunately, the thinner the films, the lower the critical temperature.” However, super-cooled superconductor chips can be better engineered for applications ranging from quantum computing to integrated ultra-low power devices. Berggren’s lab -- the Quantum Nanostructures and Nanofabrication Group, where Ivry works -- has built circuits that use only one-hundredth the energy of non-superconducting chips performing the same function. The scientists’ latest test material is niobium nitride, a socalled high-temperature superconductor. By holding constant two of the three parameters -- critical temperature, thickness, and resistivity -- they could see a clear relationship between the three parameters and a constant, which you can read about in their free paper “Universal scaling of the critical temperature for thin films near the superconducting-to-insulating transition.” Next the researchers tried out their new law on other superconductors and found it held for three dozen different superconductors (each of which had a different constant in the same formula depending on the regularity of their lattice). www.electronics-eetimes.com Electronic Engineering Times Europe January 2015 7


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