General-purpose FPGAs: an innovationless decade

Some corners of the electronics universe go years or decades without a significant technology upgrade. Passive electronic components are a good example, as not much more performance or cost can be pulled out of devices like resistors, at least not without a materials revolution. Another is the battery market, where offerings have by and large been optimized to demand.

Then there’s also the embedded processing space. That’s right, logic. Specifically, general-purpose programmable logic.

In 2011, Xilinx and Altera (now part of Intel) released the Artix-7 and Cyclone V GT, respectively. Each of these devices contained fewer than 100K logic cells (50K for the Xilinx part and up to 77K for Cyclone V devices) but delivered a nice mix of I/O flexibility, logic, and low-power consumption in applications ranging from automotive subsystems to industrial automation equipment to communications infrastructure.

And then, nothing. For almost a decade, there were no new devices introduced in the low-power, general-purpose, sub-100K-logic cell class of FPGA [field-programmable gate array].

Why not? Well, a couple of factors were in play. First, a lot of the end systems that leveraged these devices are long-life cycle deployments in industries that live by the “if it ain’t broke, don’t fix it” mantra. But the primary reason is that the two major FPGA suppliers strategically transitioned away from traditional embedded markets to capture higher-margin business in environments like the data center, which require devices with 1 million logic cells or more for things like workload acceleration.

In the absence of other competitive offerings, the size, power consumption, I/O speed, I/O density, and soft error rates (SERs) of the Artix-7 and Cyclone V GT remained the status quo for years.

Changing CMOS is the only constant

Of course, even in the most static parts of the electronics space (paraphrasing the philosopher Heraclitus), change is the only constant. And change has recently come to the sub-100K logic cell general-purpose FPGA market with Lattice Semiconductor’s Certus-NX line.

Certus-NX FPGAs are available with between 17K and 40K logic cells, and – like the alternatives mentioned earlier – include hardened 5 Gbit/sec PCIe lanes. But while the Lattice devices are comparable across those parameters and even include less RAM and fewer DSP multipliers, they deliver up to 70% faster differential I/O speeds, twice the I/O density, and 4 times lower power consumption. (Table 1.)

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Table 1 | The Certus-NX portfolio leverages the 28 nm FD-SOI process technology for lower power, improved soft-error rate (SER), and optimized performance. (Key: *Range for different package sizes; †PCIe Gen 2 interface, worst process, Tj=85 °C, 125 MHz.) Source: Vendors except †Lattice.

They are also roughly half the size, measuring just 6 mm by 6 mm.

Certus-NX devices achieve these performance and efficiency gains through a trick of Moore’s law. While the Lattice, Intel, and Xilinx FPGAs are all manufactured on 28 nm nodes, the Certus-NX platforms utilize a fully depleted silicon-on-insulator (FD-SOI) process technology that exhibits less parasitic capacitance than bulk CMOS (Figure 1). This process enables body biasing, or the ability to make transistors more performant or power-efficient by passing a programmable voltage across the layer of oxide insulation underneath them.

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Figure 1 | FD-SOI process technology enables improved power consumption and performance through techniques like body biasing.

Despite its use of already-established manufacturing techniques, FD-SOI produces smaller die sizes and is more reliable than standard CMOS. The technology virtually eliminates SERs in SRAM, which contributes to a mean time between failure (MTBF) on Certus-NX devices that is more than 150 times the competition.

Progress for progress’s sake

Other modernizations in the Certus-NX include support for ECDSA cryptographic algorithms plus 3 ms I/O configuration and 14 ms device configuration, all of which combine with the aforementioned power savings to offer a solid foundation for connected and battery-operated devices.

But just as important, the size, performance, reliability, and power improvements also represent a significant step forward for traditional embedded applications, whether legacy deployments or new installations. Let’s not forget the global footprint of these systems, and allow progress for the sake of progress to leave us with an innovation-less decade.

Brandon Lewis, the editor-in-chief of Embedded Computing Design, is responsible for guiding content strategy, editorial direction, and community engagement across the Embedded Computing Design ecosystem. A 10-year veteran of the electronics media industry, he enjoys covering topics ranging from development kits to cybersecurity and tech business models. Brandon received a BA in English literature from Arizona State University, where he graduated cum laude. He can be reached at brandon.lewis@opensysmedia.com.