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Embedded FPGAs Offer SoC Flexibility

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By Dave Lammers, Contributing Editor

It was back in 1985 that Ross Freeman invented the FPGA, gaining a fundamental patent (#4,870,302) that promised engineers the ability to use “open gates” that could be “programmed to add new functionality, adapt to changing standards or specifications, and make last-minute design changes.”

Freeman, a co-founder of Xilinx, died in 1989, too soon to see the emerging development of embedded field programmable logic arrays (eFPGAs). The IP cores offer system-on-chip (SoC) designers an ability to create hardware accelerators and to support changing algorithms. Proponents claim the approach provides advantages to artificial intelligence (AI) processors, automotive ICs, and the SoCs used in data centers, software-defined networks, 5G wireless, encryption, and other emerging applications.

With mask costs escalating rapidly, eFPGAs offer a way to customize SoCs without spinning new silicon. While eFPGAs cannot compete with custom silicon in terms of die area, the flexibility, speed, and power consumption are proving attractive.

Semico Research analyst Rich Wawrzyniak, who tracks the SoC market, said he considers eFPGAs to be “a very profound development in the industry, a capability that is going to get used in lots of places that we haven’t even imagined yet.”

While Altera, now owned by Intel, and Xilinx, have not ventured publicly into the embedded space, Wawrzyniak noted that a lively bunch of competitors are moving to offer eFPGA intellectual property (IP) cores.

Multiple competitors enter eFPGA field

Achronix Semiconductor (Santa Clara, Calif.) has branched out from its early base in stand-alone FPGAs, using Intel’s 22nm process, to an IP model. It is emphasizing its embeddable Speedcore eFPGAs that can be added to SoCs using TSMC’s 16FF foundry process. 7nm IP cores are under development.

Efinix Inc. (Santa Clara recently rolled out its Efinix Programmable Accelerator (EPA) technology.

Efinix (efinixinc.com) claims that its programmable arrays can either compete with established stand-alone FPGAs on performance, but at half the power, or can be added as IP cores to SoCs. The Efinix Programmable Accelerator technology can provide a look up table (LUT)-based logic cell or a routing switch, among other functions, the company said.

Efinix was founded by several managers with engineering experience at Altera Corp. at various times in their careers — Sammy Cheung, Tony Ngai, Jay Schleicher, and Kar Keng Chua — and has financial backing from two Malaysia-based investment funds.

Flex Logix Technologies, (Mountain View, Calif.) (www.flex-logix.com) an eFPGA startup founded in 2014, recently gained formal admittance to TSMC’s IP Alliance program. It supports a wide array of foundry processes, providing embedded FPGA IP and software tools for TSMC’s 16FFC/FF+, 28HPM/HPC, and 40ULP/LP.

Flex Logix supports several process generations at foundry TSMC. The 16nm test chip is being evaluated. (Source: Flex Logix)

QuickLogic adds SMIC to foundry roster

Menta  (http://www.menta-efpga.com/) is another competitor in the FPGA space. Based in Montpellier, France, Menta is a privately held company founded a decade ago that offers programmable logic IP targeted to both GLOBALFOUNDRIES (14LPP) and TSMC (28HPM and 28HPC+) processes.

Menta offers either pre-configured IP blocks, or custom IPs for SoCs or ASICs. The French company supports its IP with a tool set, called Origami, which generates a bitstream from RTL, including synthesis. Menta said it has fielded four generations of products that in use by customers now “for meeting the sometimes conflicting requirements of changing standards, security updates and shrinking time-to-market windows of mobile and consumer products, IoT devices, networking and automotive ICs.”

QuickLogic, a Silicon Valley stalwart founded in 1988, also is expanding its eFPGA capability. In mid-September, QuickLogic (Sunnyvale, Calif.) (quicklogic.com) announced that its eFPGA IP can now be used with the 40nm low-leakage process at Shanghai-based Semiconductor Manufacturing International Corp. (SMIC). QuickLogic also offers its eFPGA technology on several of the mature GLOBALFOUNDRIES processes, and is participating in the foundry’s 22FDX IP program.

Wawrzyniak, who tracks the SoC market for Semico Research, said an important market is artificial intelligence, using eFPGA gates to add a flexible convolutional neural network (CNN) capability. Indeed, Flex Logix said one of its earliest adopters is an AI research group at Harvard University that is developing a programmable AI processor.

A seminal capability

The U.S. government’s Defense Advanced Projects Agency (DARPA) also has supported Flex Logix by taking a license, endorsing an eFPGA capability for defense and aerospace ICs used by the U.S. military.

With security being such a concern for the Internet of Things edge devices market, Wawrzyniak said eFPGA gates could be used to secure IoT devices against hackers, a potentially large market.

“The major use is in apps and instances where people need some programmability. This is a seminal, basic capability. How many times have you heard someone say, ‘I wish I could put a little bit of programmability into my SoC.’ People are going to take this and run with it in ways we can’t imagine,” he said.

Bob Wheeler, networking analyst at The Linley Group, said the intellectual property (IP) model makes sense for startups. Achronix, during the dozen years it developed and then fielded its standalone FPGAs, “was on a very ambitious road, competing with Altera and Xilinx. Achronix went down the road of developing parts, and that is a tall order.”

While the cost of running an IP company is less than fielding stand-alone parts, Wheeler said “People don’t appreciate the cost of developing the software tools, to program the FPGA and configure the IP.” The compiler, in particular, is a key challenge facing any FPGA vendor.

Wheeler said Achronix https://www.achronix.com/ , has gained credibility for its tools, including its compiler, after fielding its high-performance discrete FPGAs in 2016, made on Intel’s 22nm process.

Achronix offers Speedcore eFPGAs, based on the same architecture as its standalone FPGAs. (Source: Achronix Semiconductor)

And Wheeler cautioned that IP companies face the business challenge of getting a fair return on their development efforts, especially for low-cost IoT solutions where companies maintain tight budgets for the IP that they license.

Achronix earlier this year announced that its 2017 revenues will exceed $100 million, based on a seven-times increase in sales of its Speedster 22i FPGA family, as well as licensing of its Speedcore embedded IP products, targeted to TSMC’s leading-edge 16 nm node, with 7nm process technology for design starts beginning in the second half of this year. Achronix revenues “began to significantly ramp in 2016 and the company reached profitability in Q1 2017,” said CEO Robert Blake.

Escalating mask costs

Flex Logix CEO Geoff Tate

Geoff Tate, now the CEO of Flex Logix Technologies, earlier headed up Rambus for 15 years. Tate said Flex Logix (www.flex-logix.com uses a hierarchical interconnect, developed by co-founder Cheng Wang and others while he earned his doctorate at UCLA. The innovative interconnect approach garnered the Lewis Outstanding Paper award for Wang and three co-authors at the 2014 International Solid-State Circuits Conference (ISSCC), and attracted attention from venture capitalists at Lux Ventures and Eclipse Ventures.

Tate said one of those VCs came to him one day and asked for an evaluation of Wang & Co.’s technology. Tate met with Wang, a native of Shanghai, and found him to be anything but a prima donna with a great idea. “He seemed very motivated, not just an R&D guy.”

While most FPGAs use a mesh interconnect in an X-Y grid of wires, Wang had come up with a hierarchical interconnect that provided high density without sacrificing performance, and proved its potential with prototype chips at UCLA.

“Chips need to be more flexible and adaptable. FPGAs give you another level of programmability,” Tate noted.

Meanwhile, potential customers in networking, data centers, and other markets were looking for ways to make their designs more flexible. An embedded FPGA block could help customers adapt a design to new wireless and networking protocols. Since mask costs were escalating, to an estimated $5 million for 16nm designs and more than double that for 7nm SoCs, customers had another reason to risk working with a startup.

TSMC has supported Flex Logix, in mid-September awarding the company the TSMC Open Innovation Platform’s Partner of the Year Award for 2017 in the category of New IP.

“Our lead customer has a working chip, with embedded FPGA on it. They are in the process of debugging rest of their chip. Overall, we are still in the early stages of market development,” Tate said, explaining that semiconductor companies are understandably risk-averse when it comes to their IP choices.

Asked about the status of its 16nm test chip, Tate said “the silicon is out of the fab. The next step is packaging, then evaluation board assembly.  We should be doing validation testing starting in late September.”

Potential customers are in the process of sending engineers to Flex Logix to look at metrics of the largest 16nm arrays, such as IR drop, vest vectors, switching simulations, and the like. “They making sure we are testing in a thorough fashion. If we screw them over, they’ll tell everybody, so we have got to get it right the first time,” Tate said.

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