February 3, 2021

NanoBridge Semiconductor, Inc., increased capital in December 2020 as a spin-off from NEC, is a business venture that designs the circuits, undertakes a package of production processes, and sells IP licenses for NanoBridge^®, the world’s one-and-only FPGA with an embedded atomic switch. We interview with Tadahiko Sugibayashi, CEO of NanoBridge Semiconductor, Inc., about the details of this technology and future prospects.

Programmable semiconductor chip offers drastic improvement in power consumption

― What kind of technology is the NanoBridge?

It is a one-of-a-kind FPGA globally. The embedded atomic switch can switch the metal wiring in the semiconductor chip, which achieves outstanding power-saving performance. Let me start my explanation with what an FPGA is. FPGA stands for field-programmable gate array, which is a semiconductor chip whose logic circuits can be configured to the user’s needs. Customization is in progress today to meticulously meet customer needs in a diversity of product fields. The automotive industry is an example of the industries need high-performance parts and components in small-lot for multi-variety products. It is extremely important for such industries to have chips that companies can configure on their own after having them delivered to their sites.
While chips can be configured using their CPU and software, but since the hardware (circuit) itself is not necessarily optimized for custom computation, there is always going to be increased power consumption.
That combined with the coming of the limitation on miniaturization, we cannot expect further groundbreaking evolution with a CPU on its own. As we are boosting performance by means of multi-core processors, keeping the power consumption down is our greatest challenge. Reducing power consumption is an issue that has been equally weighing on many industries in recent years.
Against this backdrop, a trend has emerged with the adoption of low-power FPGAs that provide custom computation by means of optimized hardware (circuit) in order to reduce power consumption. Low-power, high-performance FPGAs are garnering attention due to their key role in technologies such as IoT and AI. We saw a spate of cases of global CPU enterprises acquiring FPGA manufacturers.
NanoBridge, our low-power, high-performance FPGA can be the answer to this demand. In 2003, NEC succeeded in the demonstration of an atomic switch using solid electrolytes. Since this initial development, I have been continuously involved in the commercialization of this technology in ways such as advocating for its use in FPGAs for researchers. This is part of what helped realize this corporate spin-out. I believe that, as of today, we with NanoBridge are the only ones who have had a successful demonstration of an FPGA adopting an atomic switch or other similar technologies.

A ten-fold improvement in power efficiency and enhanced radiation resistance achieved with atomic switch

― How power-saving is the NanoBridge?

NanoBridge has a power efficiency that is approximately ten times that of conventional FPGAs. Existing FPGAs use transistors to switch circuits, but NanoBridge uses an atomic switch as the mechanism for switching metal wiring. The atomic switch is smaller in area and realizes shorter wiring compared to a transistor, which results in the reduction in power consumption to one-quarter across the entire chip.
Operating voltage can be lowered as well, providing another way to reduce the chip's power consumption. However, transistors need the voltage to be maintained at a certain level. On the other hand, the performance of NanoBridge is kept high at a lower operating voltage since NanoBridge (atomic switch) is made of metal, in which the metal can be used for direct wiring connections. This, as a result, improves the overall power efficiency by as much as a factor of ten.
Furthermore, atomic switches are non-volatile, which means that no power is needed to retain the data. Therefore, they are optimal for devices that operate intermittently, such as IoT devices. When the device is not in operation, the power supply can be shut off completely to cut power consumption.
Additionally, being made of metal gives NanoBridge radiation-resistant properties. Conventional semiconductors are suffering from unintentional data loss (error) when exposed to radiation, but such errors are non-existent with our FPGA with NanoBridge. We have already succeeded in our demonstration experiment in space, as an example of a high-level radiation setting. The NanoBridge FPGA was loaded on RAPIS-1 (RAPid Innovative payload demonstration Satellite1) launched in January 2019 by JAXA and proved the fault-free operation for over a year aboard.
As for radiation resistance, we are assuming that this quality is in demand in places other than in space. For example, since radiation can be generated by particle accelerators at medical sites or research centers, these are some places where such a property can be useful. And while this is not commonly known, a low level of radiation does reach the face of the earth, which may cause an error about once in a year in a normal environment. Business operators that work with critical infrastructure, such as basic telecommunications networks, worry about any factors that may cause data errors, including such a rare event as this, so I believe that NanoBridge can be useful for such applications as well.

Non-volatile NanoBridge to start demonstration with robots

― What future plans and prospects do you have for NanoBridge?

As of now, we have multiple demonstration experiments running, including the NEDO project. In one of such experiments, we are working with Prof. Inaba at the University of Tokyo on the low power use of robotic prosthetic legs. When people hear about reducing the power usage of a robotic prosthetic leg, they tend to focus on the motor. However, in reality, humans do not keep walking; in fact, humans rest most of the time. The intermittent human activities has great affinity for our non-volatile NanoBridge. By meticulously suppressing power usage when the wearer is resting and switching to high-performance operation when the wearer is active, we are working to prolong the battery charge as much as possible.
We have two potential markets in mind for the future. First, we are thinking of automobiles. NanoBridge supports intermittent operations, which is a feature that can be applied to the repeated stop-and-go behavior of automobiles. The automotive industry produces a variety of parts, so I believe that the programmability of FPGA can work to the advantage of the industry in this aspect as well.
Second, the application is to 5G. 5G telecommunications is said to require an increase in the number of base stations by 10 to 50 times, which also pushes up the demand for hardware. 5G is still in the process of standardization and will likely continue to evolve. Our programmable FPGA will be useful in such circumstances.
In the longer term, we will actively work on the practical application of NanoBridge with an eye to license business and business expansion nationwide and beyond.