RF GaN: A World of Potential, But at a Critical Crossword

Over the last two decades, RF GaN technology has evolved, initially finding its roots in defense applications and now exploring new frontiers in meeting the demands of telecom infrastructure and satellite communications. As GaN-on-SiC technology reaches maturity, it is emerging as a standard for various applications, steadily gaining market share over competing technologies such as Si LDMOS and GaAs. With a focus on power efficiency, reliability, and space optimization, GaN technology is becoming indispensable. The telecom infrastructure market is witnessing a significant shift in power amplifier (PA) requirements, paving the way for GaN-on-Si technology introduced by Infineon on an 8-inch platform in 2023. This strategic move not only intensifies competition with GaN-on-SiC but also could unlock new prospects, especially in the handset market. 

Driven by the demands of 5G telecom infrastructure and defense radar applications, the overall value of the GaN RF device market is projected to surge from US$1.4 billion to over US$2.2 billion, according to Yole Group's RF GaN Compound Semiconductor Monitor Q4-23 edition, exhibiting a robust compound annual growth rate (CAGR) of 8.7% during the 2022-2028 period. 

While the RF GaN market may not be evolving at quite the same pace over the 2022-28 period as wideband gap (SiC and GaN) markets for power conversion applications, it remains dynamic and is transforming its supply chain. US-based MACOM, a key player in the industry, completed two significant acquisitions in 2023 — French OMMIC SAS for its GaN-on-Si technology and US-based Wolfspeed’s RF GaN-on-SiC business, a leader in the RF GaN sector. These strategic moves position MACOM to potentially emerge as one of the leaders in RF GaN. Concurrently, players such as SEDI, Qorvo, and NXP are maintaining their strong leadership in the RF GaN industry. In China, players like SICC, Sanan IC, Dynax, and CETC continue developing and addressing the local RF GaN market. Earlier in 2023, Infineon introduced the first commercial GaN-on-Si Pa technology on 8-inch wafer to the telecom infrastructure market. Other players like ST Microelectronics, UMC, and GlobalFoundries are likely to follow in the coming years.

RF GaN Reaching Success for Several Applications

Since the 1990s, the U.S. Department of Defense has recognized the superior output power and efficiency of RF GaN-on-SiC compared to materials such as InP, GaAs HBT, GaAs HEMT, and Si LDMOS. RF GaN not only offers a broader bandwidth but also facilitates a reduction in system size – two attributes highly sought after as telecom infrastructure expands its frequencies and base station models. 

The exceptional power and efficiency characteristics of RF GaN have led to its widespread adoption in defense applications, particularly in addressing thermal challenges in higher-power scenarios, such as airborne radar systems. Defense continues to stand out as one of the largest sectors in the RF GaN market. 

Airborne systems, characterized by a high device count, are expected to dominate the market, with an increase also foreseen within shipborne systems in the coming years. Beyond the borders of the United States, both Europe and China are actively cultivating their GaN ecosystems, with a specific focus on expanding deployment in military radar applications. Although the electronic warfare market remains largely concealed and shrouded in secrecy, sustained growth is assured from the ongoing demonstrations and GaN projects within this segment. GaN enjoys industry favor over alternative technologies owing to its broadband operation and enhanced reliability. Substantial growth in military satellite communication is anticipated during the period spanning 2022 to 2028. GaN devices emerge as the preferred choice for deploying Ka-band block upconverter systems, showcasing a blend of high-power output and lightweight properties. In the realms of C and X bands, the selection of GaN systems is guided by the crucial criterion of Power-Added Efficiency (PAE). 

Simultaneously, RF GaN has begun making inroads into the SatCom market, leveraging its high efficiency compared to other materials to enable smaller device sizes, thereby saving valuable space at the system level. After the telecom infrastructure and defense markets, satellite communication is the third-largest RF GaN market and is expected to reach US$270 million by 2028 with an 18% CAGR_2022-2028. RF GaN power amplifiers offer higher data throughput, smaller antennas, wider bandwidth, and better efficiency. Transitioning from L/C/X-bands to Ku/Ka-bands enables higher data rates in mobile satellite communication. While traveling wave tube (TWT) technology was dominant historically, it has limitations, such as bulkiness and reliability issues. Solid state power amplifiers (SSPA) based on GaAs are gaining interest for low-power and lightweight satellite systems but have efficiency and bandwidth limitations compared to GaN. GaN PAs offer numerous advantages over GaAs SSPAs, making them attractive for various applications like GEO HTS, “New Space,” LEO, and Earth observation at higher frequencies. We are witnessing a growing focus on satellite communications, particularly due to the rising interest in the “New Space” trend. Additionally, the telecom infrastructure industry is showing increased attention to satellite communication, especially with Space X's plans to provide 5G coverage through satellite technology. This approach raises the possibility of a world without areas lacking reliable phone network coverage. RF GaN technology can take this opportunity to increase its presence in the market. 

Originally introduced by Huawei in 2015, volume production of GaN-on-SiC for telecom infrastructure began in 2020 for 4G base stations. Since then, RF GaN technology has benefitted from the 5G rollout by meeting the new base station requirements and replacing LDMOS technology. There have also been significant investments from companies around the world, such as SEDI, Wolfspeed (whose RF business is now part of MACOM), NXP, and Qorvo, ensuring GaN-on-SiC dominates in its target applications and replaces its counterpart Si LDMOS. 

4G micro and macrosite base stations are predominantly based on remote radio heads (RRH), integrating the base station’s RF chains and analog-to-digital conversion components with up to eight multi-stream PAs at up to 100W output power. 

As the 4G era is coming to an end, the reliance on LDMOS-based PAs in 3GHz base stations is expected to recede. Emerging sub-6GHz 5G base stations are moving from a 2x2 MIMO model to a 64x64 Massive MIMO (mMIMO) with active antenna systems (AAS) replacing RRHs. 

At the same time as increasing the number of PAs, each PA is expected to operate with a lower output power (from 100W to 5W). PAs are also required to handle increasing data traffic volumes while reducing power consumption. 

GaN can address all these requirements. The LDMOS market share is expected to decline as GaN-on-SiC addresses frequencies up to 7GHz for 5G. For 5G mmWave and 6G, as the requirements are more for high frequencies and lower power, RF GaN technology is expected to face tougher competition with other materials such as SiGe and InP technology. 

How can RF GaN evolve? 

As the sub-6GHz 5G telecom base station demands PAs with lower power, GaN-on-Si stands to carve a niche in 32T32R / 64T64R mMIMO base stations operating below 10W. Over the past two years, key players like STMicroelectronics with MACOM, OMMIC (now part of MACOM), GCS, Infineon Technologies, and foundries such as Global Foundries and UMC have collaborated to introduce RF GaN-on-Si technology. 

The shift to mmWave small cells (2- and 4-stream) operating at 28 – 60GHz with reduced output power presents an additional opportunity for GaN-on-Si. As telecom infrastructure increasingly adopts lower output power systems, the adoption of GaN-on-Si is propelled by the requirements of Antenna Array Systems (AAS) and small cells to meet the demands of multi-stream, small cell, and mmWave beamformer performance. Looking ahead to the next generation, 6G, which will feature even higher frequencies, GaN-on-Si is anticipated to coexist with the incumbent technology, GaN-on-SiC.

In a significant development this year, Infineon Technologies introduced GaN-on-Si PAs on 8” technology to address the telecom infrastructure market. Anticipating a trend, other major players like Global Foundries, UMC, MACOM, and STMicroelectronics are expected to follow suit in the coming years. Notably, many players opt to enter the market directly with GaN-on-Si, bypassing the use of GaN-on-SiC technology. 

GaN is projected to constitute over 87% of telecom infrastructure PA device shipments by 2028. Within this, more than 77% will be GaN-on-SiC and 10% GaN-on-Silicon, while LDMOS is expected to lose market share.

The prospects for GaN-on-Si technology extend to 5G handset power amplifiers in the FR3 band. While there is potential for GaN-on-Si in sub-7GHz and 5G mmWave frequencies for handset PAs, it's essential to acknowledge the existing dominance of well-established GaAs solutions in sub-7GHz and the traction gained by silicon-based solutions in mmWave applications. These technologies, having matured both in terms of technology and supply chain, present themselves as significant competitors. In the open competition of FR3, GaN-on-Si holds promise but requires complex design changes for integration into handset systems, making its adoption in the FR3 band a longer-term goal. 

The decisive influence of the fate of GaN-on-Si technology ultimately lies with smartphone Original Equipment Manufacturers (OEMs) such as Apple, Samsung, and Xiaomi, potentially serving as a turning point for the GaN-on-Si industry.  

A Moving Ecosystem for a Dynamic Market. RF GaN Still Raises Attention and Questions.  

Today, GaN-on-SiC, as the primary platform, has a well-established supply chain. Device suppliers such as SEDI, Qorvo, Wolfspeed and NXP, as well as defense-related companies Raytheon, BAE Systems, and Northrop Grumman, offer GaN-on-SiC technology. In 2022, SEDI, Qorvo, and Wolfspeed were the leading players in RF GaN. As a newcomer in the GaN space, NXP has experienced significant growth by entering the telecom supply chain with the opening of its 6-inch GaN-on-SiC fab in the US in 2020. In a short time, the company, which also has an LDMOS offering, has become a leading player in the GaN-based telecom infrastructure sector. Furthermore, GaN-on-SiC has welcomed innovative players like Altum RF, mmTron, and Gallium semiconductors over the last few years. Now, this expanding industry makes more room for GaN-on-Si technology, where low-power GaN solutions are promising for 32T32R / 64T64R mMIMO base stations below 10W, with ever more products becoming available this year. 

The S.I. SiC wafer market remains shared by the three major suppliers, Wolfspeed, Coherent, and SICC. In the defense segment, Raytheon, Northrop Grumman, and Chinese CETC are leading in the adoption of GaN. DoD-trusted Wolfspeed and Qorvo also serve as GaN foundries. Focusing on the supply to the telecom market, Ericsson and Nokia keep stretching the supply of the volume of RF GaN devices from multiple device suppliers while Samsung cooperates closely with Korean device players. Since the US sanctions, Huawei and ZTE have turned to the Chinese supply chain to develop domestic capability. 

To overcome the US sanctions, China continues developing its domestic RF GaN technology and the Chinese supply chain. In the GaN-on-SiC eco-system, the leading players are world-class at the wafer and end-system levels, such as SICC, Sanan IC, CETC, Dynax, Huawei, and ZTE. Since 2020, China has been accelerating the development of epiwafer, front-end, and back-end processes and design. More than one active player at each level has been identified, showing the Chinese ecosystem’s progress in the past two years. At the device level, GaN-on-SiC at the 0.25µm node has become available from HiWafer and Sanan IC to serve the existing sub-6GHz market. In our understanding, Sanan IC is also working to develop GaN-on-Si technology.

Yole Intelligence's RF GaN 2023 report accurately predicted Wolfspeed's decision to divest its RF business, marking a strategic shift toward SiC power technologies. Acquired for US$125 million from Infineon Technologies after an initial purchase of US$345 million in 2018, this move positions Wolfspeed as the primary player in the power SiC industry. The decision to cease supplying competitors after the sale enhances their potential for expansion. 

In parallel, MACOM's early exploration of GaN-on-Si and alignment with STMicroelectronics since 2018 has positioned it as a pioneer. The successful production of RF GaN-on-Si prototypes in 2022 reflects their commitment to introducing GaN-on-Si technology, emphasizing applications in the telecom and consumer sectors. MACOM's strategic acquisition of OMMIC SAS in 2023 showcases their dedication to mmWave technology, enhancing their portfolio for the defense and aerospace sectors in the US and Europe. 

Responding to defense sector demands, MACOM strategically shifted focus to GaN on SiC technology in the early 2020s, specializing in high-power devices up to 7kW. Collaborating with the US defense sector, their partnership with the Air Force Research Laboratory achieved significant progress in GaN on SiC technology, operating at high frequencies in the K to Ka-band. 

MACOM's recent acquisition of Wolfspeed's RF business strengthens its position in the defense, aerospace, and telecom markets. Leveraging Wolfspeed's standing in the RF GaN market, MACOM has solidified its strategic presence, emphasizing its commitment to expanding its share in the RF GaN market with a comprehensive portfolio covering GaN-on-Si and GaN-on-SiC technologies across a wide frequency range. 

Regarding the GaN-on-Si ecosystem over the last years, companies such as STMicroelectronics, MACOM, Infineon Technologies, and foundries like Global Foundries and UMC have been actively involved in the development and introduction of RF GaN-on-Si technology. Infineon Technologies introduced GaN-on-Si PA technology on 8” wafer earlier this year to address the telecom infrastructure market. We expect other players to follow.

Companies like GlobalFoundries, STMicroelectronics, and Infineon are already active in the power GaN industry. Despite challenges such as technology node and epitaxy control, these players are exploring synergies between RF and power GaN, leveraging similar GaN-on-Si technologies to address distinct markets.

Additionally, innovative companies are entering the ecosystem, like Finwave, which is focused on developing 3DGaN FinFET technology on 8-inch GaN-on-Si wafers. They are utilizing standard silicon foundry tools in their development process. Alongside these innovative companies, established companies like GCS, UMC, Sony, and Global Foundries have the potential to adapt and enter the market quickly.

The players are preparing for these killer applications to run their technology and open a new era for high-volume GaN-on-Si manufacturing in the RF industry.

What comes after for the RF GaN industry?

In conclusion, the RF GaN industry has transformed over the last two decades, moving from dominating in defense applications to coexisting in several markets, such as telecom and satellite communications. GaN-on-SiC technology has become a mainstream technology in defense and telecom infrastructure PAs, gaining market share. The introduction of GaN-on-Si in telecom infrastructure hints at growth and opens new opportunities. Yole Group's RF GaN Compound Semiconductor Monitor Q4-23 edition predicts strong growth, driven by 5G and defense applications, and expects the RF GaN device market to exceed US$2.2 billion by 2028. 

The year 2023 has been significant so far, with two remarkable strategic acquisitions from MACOM that could help them gain more market share in the current landscape, while Infineon introduced the first GaN-on-Si Pa technology based on their 8-inch platform. 

Globally, GaN is gaining importance in defense, particularly in airborne systems. The advent of 5G offers opportunities for GaN in mMIMO base stations, extending into the anticipated 6G era. GaN-on-Si shows promise in handset technology trends but faces stiff competition from established platforms. The RF GaN-on-Si supply chain is diversifying with new players, fostering sustainable market growth in the future. 

In the final analysis, the RF GaN industry stands at a pivotal juncture as GaN-on-Si technology matures. This prompts contemplation: Is it the opportune moment to explore new growth prospects in untapped markets? Alternatively, will GaN-on-Si manage to secure a larger market share over GaN-on-SiC? 

About the Authors

Aymen Ghorbel is a Technology & Market analyst at Yole Intelligence, part of Yole Group, specializing in Compound Semiconductors and Emerging Materials. As a member of the Power & Wireless division, Aymen is engaged in developing technology and market reports and is also involved in custom projects. Aymen previously worked as an Electrical Characterization Engineer and as an Innovative Product Development engineer at Soitec. He co-authored five papers in high-impact scientific journals and two patents. Aymen obtained an engineering degree in Material Sciences in 2016 from École Polytech‘ Grenoble  (France) and an M.S. in “Technology and Innovation Management” in 2017 from Grenoble Ecole de Management (France).

Ezgi Dogmus, Ph.D., is Team Lead Analyst in Compound Semiconductors & Emerging Substrates activities within the Power & Wireless Division at Yole Intelligence, part of Yole Group. With an international team of technology & market analysts, Ezgi manages the expansion of the organization’s technical expertise and market know-how. In addition, Ezgi actively assists and supports the development of a dedicated collection of market & technology reports, Monitors, and custom consulting projects. Prior to Yole, Ezgi worked as a process development engineer on GaN-based RF and power solutions at IEMN (Lille, France). After graduating from the University of Augsburg (Germany) and Grenoble Institute of Technology (France), Ezgi received her Ph.D. in Microelectronics at IEMN (France).