Manager of the Power Stage Product Development Department
Kenichi Yoshimochi is Division Manager of the Power Stage Product Development Department that develops products for GaN devices and GaN dedicated control IC.
He graduated with a master’s degree in Materials science and engineering from Kyushu University, and as a carrier until now, he has developed Si MOSFET devices/products and marketed them.
Taha’s expertise is mainly in power electronics with related WBG materials and emerging semiconductor substrates. He is fully engaged in the development of technology and market products, as well as custom projects.
Taha has two years’ experience as a Technology & Cost Analyst at Yole Group, where he focuses on the development of compound semiconductor reverse engineering & costing analyses.
Prior to Yole Group, Taha was a research engineer at Georgia Tech Lorraine (Metz, France). He published numerous papers with a particular focus on III-N materials.
Taha holds an MSc and a Ph.D. in electrical and computer engineering from the Georgia Institute of Technology (Atlanta, USA).
Oluwasayo Loto, PhD
Technology & Cost Analyst, Power Electronics
With a solid expertise in the process development and electrical characterization of diamond power transistors, his mission is to develop reverse costing reports on innovative Si and GaN- based power devices and other emerging technologies.
Prior to Yole Group, Oluwasayo worked as an R&D engineer with CEA and CNRS on the development of semiconductor detectors and power device applications respectively. He has made significant contribution to yield improvement of diamond device fabrication.
Oluwasayo holds a PhD in nanoelectronics and nanotechnologies from the University Grenoble Alpes (France) and a double masters degree in materials science and engineering from TU Darmstadt (Germany) and Grenoble INP Phelma (France).
Consumer fast chargers and adapters continue to be the primary driving forces behind the growth of power GaN technology. Recent trends encompass higher power capacities, reaching up to 300W, and ‘all-GaN’ chargers, which contribute to increased utilization of GaN per charger. Besides the consumer sector, Yole Intelligence anticipates two additional growth catalysts for power GaN: automotive and data center applications, which are poised to elevate the device market to over $2 billion by 2028.
ROHM, as a frontrunner in the power electronics market, has made significant strides after entering the power GaN business by introducing new products in 2022.
For a deeper insight into ROHM’s initiatives and future plans, Taha Ayari, Technology and Market Analyst at Yole Intelligence, and Olusayo Loto, Technology and Cost Analyst at Yole SystemPlus, have the pleasure to interview Kenichi Yoshimochi, Manager of the Power Stage Product Development Department at ROHM.
Yole Intelligence and Yole SystemPlus are part of Yole Group.
150V GaN HMET GNE10xxTB series (GNE1040TB) – Courtesy of ROHM, 2023
Taha Ayari (TA):Please provide a brief introduction about yourself to our readers.
Kenichi Yoshimochi (KY): Nice to meet you. I am Kenichi Yoshimochi. My current position is Division Manager of the Power Stage Product Development Department. My department develops products for GaN devices and GaN dedicated control ICs. Our major research field is material-related engineering, and until now, we have developed and marketed Si MOSFET devices/products. My private hobby is trail running.
TA: Please give us a brief history of ROHM’s involvement in power GaN development.
KY: Improving the efficiency of power supplies and motors, which are said to account for most power consumption worldwide, is a global societal issue to achieve a decarbonized society.
The key to improving efficiency is power devices, and the use of new materials, such as SiC and GaN, is expected to further improve the efficiency of various types of power supplies.
ROHM has developed and mass-produced a wide range of distinctive silicon devices as well as industry-leading SiC devices.
At the same time, ROHM has also developed GaN devices that excel in high-frequency operation in the medium-voltage range. Stable and high-quality manufacturing of GaN HEMTs is essential for the full-fledged diffusion of GaN devices. Manufacturing technology to maintain high quality is essential for growing GaN epilayers, particularly in GaN on Si technology. ROHM has the basic epi and growth technologies that we have developed over many years for the reliable mass production of LED products.
150V GaN HMET GNE10xxTB series (GNE1040TB) – Courtesy of ROHM, 2023
By applying our expertise to GaN HEMTs, we are able to provide a stable supply for markets that require long-term reliability. After about 20 years of R&D, GaN HEMT with 150V breakdown voltage, which was first mass-produced in 2022, has succeeded in increasing the gate/source rated voltage from a typical 6V to 8V by its unique construction and will be able to improve the design margins and increase the reliability of power supply circuits employing GaN devices.
Furthermore, in order to maximize the low-loss, high-speed switching performance of GaN HEMTs and achieve stable performance in the application, a dedicated IC that can provide stable control is required in addition to the robustness of the device itself. In response to this challenge, ROHM has developed analog-based IC design techniques for GaN HEMT to meet new market demands and contribute to solving societal issues. We are developing and commercializing gate drivers, controllers, and other products that enable stable control of GaN through our EcoGaN™ branding, which is a generic name for devices equipped with GaN.
TA: We saw ROHM entering the Power GaN market in 2022 by releasing its first EcoGaN product. As of 2023, discrete 150V and 650V devices are available.
Could you please comment on your product portfolio roadmap? Are you considering a 1200V device?
KY: First, we will respond to the 150V and 650V roadmaps.
Pressure-resistant 650V products:
Started mass production of single GaN HEMTs in April 2023: HERE. In June 2023, we began mass production of a GaN HEMT and gate-drive IC packaged in the same SiP (System in Package – built-in GaN HEMT): HERE. In 2024, we plan to begin mass production of a GaN HEMT with a gate-drive IC and power control IC in the same package. Specifically, we plan to begin mass production of a power supply control IC equipped with a pseudo-resonant AC-DC circuit or a power factor correction circuit in the first quarter of 2024. In the second quarter of the same year, we are scheduled to begin mass production of products equipped with a control IC for half-bridge circuits. Within three years, we plan to begin mass production of a single gate drive IC for use in combination with a GaN HEMT with a breakdown voltage of 650V, a single power supply control IC, and a combined gate drive IC and power supply control IC.
650V GaN HEMT GNP1070TC-Z(Lower side), GNP1150TCA-Z(Upper side) – Courtesy of ROHM, 2023
Pressure-resistant 150V Products
Started mass production of single GaN HEMTs in March 2022: HERE. Within three years, we plan to develop the following products one by one. We are planning to develop automotive products, but at the moment, we are unable to state exactly when. GaN HEMT and gate-drive IC in the same package. GaN HEMT, gate-drive IC, and power supply control IC in the same package. Gate drive IC single unit, power supply control IC single unit, and gate drive IC and power supply control IC integrated with a GaN HEMT with a breakdown voltage of 150V.
Olusayo Loto (OL): It is common to see newcomers to the GaN business trying to get market share in consumer power supply applications which offer high volumes and fast time-to-market.
What is your strategy to get your initial revenues from power GaN? What are the main applications that you are addressing?
KY: First of all, it needs to solve a problem from the user’s point of view. One such product is a SiP (System in Package) in which 650V GaN HEMT, gate drivers, and peripheral components have been mass-produced since June 2023. By providing GaN HEMTs with difficult-to-handle gates in conjunction with dedicated gate drivers optimized for this application, it is also easy to replace conventional silicon-powered MOSFETs. The integration of analog technologies, which ROHM excels at, into our product development and product lineup expansion is another ROHM-exclusive strategy.
For example, analog is integrated into the Nano series, which was announced in 2017 and is continuing to expand its lineup. Nano series is a generic term for innovative power supply technologies that ROHM has developed using analog-control technologies. It now consists of three basic techniques, “Nano Pulse Control™,” “Nano Energy™,” and “Nano Cap™,” and dramatically reduces the size and energy consumption of conventional power supply devices. GaN devices have extremely high energy conversion efficiency and can achieve energy savings and miniaturization in a variety of fields, but no matter how high the energy conversion efficiency is, any delay in driving the IC that controls it will lose the benefits.
Power Stage ICs BM3G0xxMUV-LB – Courtesy of ROHM, 2023
However, by incorporating Nano Pulse Control™ into controllers and other devices that can achieve the world’s fastest nanosecond pulse-width, ultra-high-speed switching will be achieved by maximizing the performance of GaN devices. We believe that GaN Devices are also a key technology.
Therefore, we need to offer “solutions that include peripheral components.” In addition to providing evaluation/simulation tools, ROHM has also worked to establish a support system through FAE (Field Application Engineer).
Kenichi Yoshimochi
Manager of the Power Stage Product Development Department at ROHM
I think that this strong point of ” solutions that include peripheral components ” is more applicable to GaN with its high-frequency drive potential than to SiC.
Data centers are one area where the superiority of GaN devices can now be utilized. In recent years, demand for data centers has been increasing rapidly, and huge power dissipation has become a problem. However, using highly power-conversion-efficient GaN in the power supply section can realize significant energy savings. In consumer products, such as AC adapters, PCs, TVs, and air conditioners, the use of GaN devices can reduce energy consumption and the size and thickness of applications. We believe that GaN devices can save energy and reduce size in fields such as OBC (OnBoard Chargers), and we are currently developing products for automotive applications.
OL:ROHM is a vertically integrated player for SiC and Si. Do you have the same business model for Power GaN? If so, could you comment on your manufacturing facility for Power GaN? Are you processing on 8-inch wafers? If not, are you working with external foundries like most Power GaN fabless companies do?
KY: Though ROHM is an integrated player, we use foundries and OSATs in production processes if there are cases where they can offer specific advantages. Our apologies, but we cannot disclose the wafer size or the specific names of the companies.
OL:We understand that you have a close collaboration with the Taiwanese startup ANCORA; could you comment more on this partnership?
KY: ANCORA is a spin-off venture of Taiwanese Delta and is part of our collaboration with Delta, which enters into strategic partnerships in the GaN devices business. ROHM expects this technology to help develop and expand the business of GaN devices. We will contribute to solving societal issues by advancing GaN devices/control ICs to develop new applications for Delta through this collaboration.
TA: Lastly, would you like to share any closing thoughts or additional insights for our valued readers?
KY: In 2020, ROHM established a new management vision called “We focus on power and analog solutions and solve social problems by contributing to our customers’ needs for “energy savings” and “miniaturization” of their products.”
In the power sector, we will continue to develop and mass-produce next-generation power semiconductors, including SiC, which is ideal for high-voltage applications, and GaN, which is ideal for high-frequency applications. In the analog field, we are developing and mass-producing power supply ICs, driver ICs, and other products that incorporate industry-leading technologies, such as the Nano series.
We have already developed these products. ROHM’s strengths include the ability to combine these distinctive products and provide them as solutions. ROHM aims to be a company that contributes to society through these corporate activities and can meet the expectations of its stakeholders.
Kenichi Yoshimochi Manager of the Power Stage Product Development Department at ROHMI think that this strong point of ” solutions that include peripheral components ” is more applicable to GaN with its high-frequency drive potential than to SiC.
