GaN technology a hot topic again at IMS

Every month the McHale Report will host an online roundtable with experts from the defense electronics industry – from major prime contractors to defense component suppliers. Each roundtable will explore topics important to the military embedded electronics market. This month we discuss trends in the military RF & microwave market and the buzz at the International Microwave Symposium () held last month in San Francisco.

This month’s panelists are: Dr. Doug Carlson, Vice President of Strategy, and Thomas Galluccio, Director of Marketing, Aerospace and Defense at MACOM; Bryan Goldstein, General Manager of the Aerospace and Defense business at Analog Devices; and Gavin Smith, RF Aerospace & Defense Product Marketing at NXP.

MCHALE REPORT: What trends did you see emerging at the International Microwave Symposium (IMS) last month in San Francisco? What was the buzz?

CARLSON & GALLUCIO: In terms of military applications, we continue to see strong interest in RF technologies that underpin (AESAs) – or Active Antenna Arrays. This reflects in part the growing effort to streamline radar development and manufacturing cycles and lower system costs by leveraging best practices established in the commercial domain. Working in partnership with MIT Lincoln Laboratory, we’ve demonstrated that a greater than 5X reduction in the cost of active array front ends can be achieved leveraging commercial manufacturing processes and a . This is driving a lot of interest in the military domain as well as for civil radar infrastructure.

We also saw renewed interest in high-reliability space products at IMS. The supplier ecosystem in this domain is consolidating, and some component providers are shifting their focus to commercial markets. So aerospace and defense OEMs are paying increased attention to the high-rel product supply chain, and are taking note of the suppliers who are strengthening their investment in this technology.

SMITH: The major trends we saw demonstrated at IMS and through conversations with attendees was centered on electronic warfare, wideband communications, radar, and cooking applications. At our booth specifically we received a lot of interest in high power solutions that have the operability to stretch across multi-octaves.

On the consumer side, there was a lot of buzz for cooking applications. Companies continue to replace clunky hardware for solid-state solutions and microwave heating is becoming a main focus. I think this was one of the most interesting IMS conferences in many years as there are so many emerging opportunities for the RF and microwave industry.

GOLDSTEIN: What was striking to me was the number of demonstrations focused on system-level impact rather than component level performance. While the performance is still critical, it is the explanation of how this new performance level benefits the customer that is now expected.  Analog Devices introduced a number of new products at the IMS and every one of the products was integrated into a complete subsystem for demonstration. The response was extremely positive. 

Gallium Nitride (GaN) continues to be a hot topic with new levels of performance being demonstrated each year. Phased-array antenna technology also continues to be a strong trend with new core chips being announced by multiple companies for applications from X-band through W-band. Integrated transceivers were also a hot topic. Higher levels of integration have been achieved, significantly reducing size, weight, power (SWaP) and overall system complexity of future communications, radar, and electronic warfare systems.

MCHALE REPORT: Aside from military what other RF & microwave application areas were popular at IMS? Automotive? Communications?

GOLDSTEIN: The automotive industry continues to grow in presence at the show with the introduction of new products focused on 24 GHz and 77 GHz radar applications. The continued cost reductions achieved through high levels of integration on silicon have enabled the introduction of radar sensors on most models of new automobiles. The volume of cars utilizing RF & microwave technology is growing very quickly.

The electronic test and measurement market continues to expand its use of RF & microwave products to enable smaller hand-held battery powered products that have the same performance as the older larger models and at a fraction of the cost. Small size and low power consumption are critical to these applications. 

Lastly, communications continues to be one of the key applications focused at the IMS show. The race to has focused many companies to develop low cost millimeter-wave technologies to support the wide bandwidth requirements and phased-array technologies needed to support the newest antenna requirements. Developing in parallel to 5G is the new class of communications micro-satellites that are expected to launch over the next decade. Millions of ground terminals with phased-array antenna technology will be required to communicate with these satellites. New products will be introduced for both the satellite systems and the ground systems and both are expected to utilize commercial technologies. These new satellites will have shorter lifetime expectations and will require lower cost solutions than current satellite programs. Lower cost plastic packaged components with some minimum level of radiation tolerance and reliability screening will be used to help reduce costs.       

CARLSON & GALLUCIO: We saw strong interest in GaN-based RF components for basestations and RF energy applications. The wireless basestation market is fueling tremendous innovation in GaN technology. GaN is now challenging LDMOS’ multi-decade dominance in basestation power amplifiers, and the implications for basestation performance and operating costs are profound. The clear technology advantages that GaN provides – improved energy efficiency, greater bandwidth, higher power density, smaller form factors – position it as the natural successor to LDMOS for the next generation of basestations, particularly for cellular bands above 1.8 GHz.

For RF energy applications, the intersection of GaN performance and silicon cost structures opens a massive opportunity to leverage solid-state RF energy as a highly efficient and precise heat and power source for a wide range of commercial applications including microwave ovens, automotive ignition, lighting systems and industrial, scientific and medical (ISM) applications including RF plasma lighting, material drying, blood and tissue heating and ablation, and beyond. The RF devices that underpin these systems must strike an optimal balance of performance, power efficiency, small size, and reliability, at a price point that promotes mainstream commercial adoption. Rugged, plastic-packaged GaN power transistors have emerged as a compelling and cost effective solution.

SMITH: A popular area seemed to focus on 5G and to a lesser extent the Internet of Things (). There is an enormous amount of 5G related research and development underway throughout the world, especially in the U.S., Europe, China, Japan, and Korea. Proof of this was the frequent questions centered around 5G and the technical papers on the topic. 5G is the first generation of cellular that will encompass more than smartphones and tablets, supporting the dozens of applications that collectively fall within IoT connectivity. This includes everything from next-generation factories to autonomous vehicles, telemedicine, smart cities, and . Even though 5G is a few years out, this technology is ground breaking for the wireless industry and will take time for integration.

As for IoT, it may not be obvious but it’s already here, as hundreds of companies are connecting sensor-enabled devices at this point using 2G cellular, and this is just the tip of the iceberg. The Internet of Things would just be “things” without the RF and microwave technology required to connect them.

Small cells were also a major topic at IMS, as they will be needed to support high data rates, low latency, and quality of service needed as cellular bands rise above its current 2.6 GHz. A final major topic was the ecosystem required by vehicle autonomy and safety, which rely heavily on RF and microwave vehicle-to-vehicle and vehicle-to-infrastructure as well as the growing number of radar systems on vehicles.

MCHALE REPORT: GaN continues to be the hottest tech in the industry, but there also seems to be more education needed for the customer base on its benefits and where and when to use it? Is that true?

SMITH: The benefits that GaN features provide are well publicized, but the relative position of GaN vs. other device technology requires careful review based on the design parameters of a particular application. GaN is a rapidly evolving technology, but so are other power semiconductor technologies. New applications emerge over time. For example, GaN got its “trial by fire” in defense systems, but is already making significant inroads into wireless infrastructure and several other sectors, all in the span of less than 10 years.

Of the RF and microwave semiconductor technologies GaN is the newest, and its characteristics and requirements are unique from the others. For example, its power-up sequence must be strictly adhered to, and as GaN has very high power density, circuits incorporating GaN devices must be designed to dissipate large amounts of heat. These are just two of the many factors that must be considered, beginning at the very earliest stages of design.

GOLDSTEIN: From my perspective, there seems to be confusion as to when to choose GaN components as opposed to LDMOS and Gallium Arsenide (GaAs). In some applications the answer is very clear, and in others it is not so clear. If the application requires efficient pure saturated RF output power at frequencies above 4-5 GHz, and power levels above 5-7 W, then GaN is the clear choice. However, GaN has much worse linearity characteristics than GaAs, so for communication applications where linearity is critical, tradeoffs need to be made between combining multiple GaAs amplifiers, which are much more linear, or working with a significantly lower number of GaN devices. In the area of low noise amplifiers (LNAs) and RF switches, the performance being achieved on GaN is now coming close to matching that of GaAs in terms of gain/loss, and noise figure while achieving much higher levels of power handling. As the volume of GaN increases and the cost decreases, it is expected that GaN will replace GaAs for many future applications. Where LDMOS maintains its position, is in the area of power amplifiers below 4 - 5 GHz. Power levels on par if not superior to GaN can be achieved at a fraction of the current price point. So in these applications, LDMOS will remain strong.

CARLSON & GALLUCIO: GaN’s performance benefits are well known to all involved with the RF and microwave industry today. But GaN’s historical cost structure made it prohibitively expensive, which slowed its mainstream adoption.

This is no longer the case, however, and customers’ perceptions and expectations for GaN are evolving accordingly. Taking into account the inherent power density advantage and scalability to 8-inch substrates, Gen4 GaN on Silicon (GaN on Si) is expected to yield GaN-based devices that are half the semiconductor cost per watt of comparable LDMOS products and significantly lower cost than comparably performing but more expensive GaN on Silicon Carbide (GaN on SiC) wafers at volume production levels.

So parallel advancements in the GaN supply chain and GaN technology roadmap have enabled the manufacturing scale and cost structures necessary to allow GaN to penetrate into commercial domains like wireless basestations, RF energy applications, and beyond. For customers evaluating where GaN does and doesn’t fit based on performance and cost metrics, Gen4 GaN changes the equation considerably.

MCHALE REPORT: Do you see growth for RF and microwave technology use in military applications? Which military applications are the best bets?

CARLSON & GALLUCIO: We anticipate that the demand for RF and microwave technology will continue to grow for military radar applications. AESAs will play an increasingly vital role within the overall sensor mesh network, spanning air, land, sea, and space domains. And as these systems become more affordable and easier to manufacture, their proliferation will accelerate. At the system level, the number of RF elements onboard an is considerably higher than with legacy radar systems. So as AESA deployments ramp up, the aggregate RF content footprint expands exponentially.

SMITH: Wider range, more precise detection, more efficient systems, are all current trends that point to growth and the need for innovative RF and microwave technology. [We focus our] products used in aerospace and defense applications focus on three major areas: radar, communications, and electronic warfare. RF is an essential component in radar applications for DME [distance measuring equipment], TACAN [tactical air navigation system], IFF [identification friend or foe], data links, and more. Although it can take several years to update current systems, the need for technological advances is clear to us.

GOLDSTEIN: RF and microwave technology is prevalent in radar, electronic surveillance/countermeasures, and communications systems for military and space applications.  As radar systems transition to phased-array antenna, the volume of electronics required increases dramatically from less accurate and less reliable single rotating antenna architectures. New radars will have thousands of antenna elements and these architectures will require RF & microwave electronics in the areas of transmit/receive functionality, up/down conversion, and frequency synthesis. Electronic countermeasures/surveillance has been made a priority by the U.S. government and new initiatives require RF & microwave components with wider bandwidths, improved efficiencies, and faster frequency hopping capabilities. 

The new communications architectures are being simplified by integrated radio-on-a-chip silicon solutions. These new transceiver chips include transmit and receive high-speed converters and frequency up-conversion with frequencies currently as high as 6 GHz. This single chip solution covers many current military communications applications, which require operating frequencies up through Ka-Band, such as VSAT. These utilize these new transceivers, which can then be cascaded with further RF & microwave content to achieve higher frequency bands. As you can see, these applications are full of microwave content and these areas are the focus of new systems and system upgrades needed by the aerospace and defense industry.

For more from our panelists read these interviews with:
Doug Carlson: Military RF market expanding thanks to GaN, commercial manufacturing practices
Bryan Goldstein: RF & microwave innovation drives military radar and electronic warfare applications.