Interview with Klaus Werner from the RF Energy Alliance

  • Klaus Werner - Executive Director, RF Energy Alliance

RF Energy

everything RF Interviewed Dr. Klaus Werner who is the executive director of the RF Energy Alliance. Dr. Werner was previously with NXP Semiconductors as the solid state RF Energy markets business development manager. He studied physics at the RWTH Aachen University, Germany, and holds a Ph.D. in Semiconductor Device Technology from Delft University of Technology, Netherlands. Dr. Werner started his professional career as a process engineer at Philips Semiconductors. Prior to his assignment in the RF power device business, he worked in several engineering and operational management functions.

Q. Can you tell us a little about the RF Energy Alliance? Can you give us some information about its inception and the core objective behind the Alliance?

The RF Energy Alliance (RFEA) is a non-profit technical association dedicated to presenting solid-state RF energy’s (SSRFE) true potential as a clean, highly efficient and controllable heat and power source. 

Founded in September 2014, members embarked on a mission to foster a sustainable marketplace around this SSRFE technology by contributing to the evolution of existing applications as well as the creation of new ones.

The Alliance is always excited to welcome new members that share the same goals: standardize, promote and educate the market in SSRFE systems for all kinds of heating, treating and processing applications. Membership represents the entire SSRFE supply chain – all offering their respective expertise and resources in this field.

Promoter companies include: Ampleon, E.G.O. Elektro-Gerätebau GmbH, Huber+Suhner, Rogers Corporation, Panasonic and Whirlpool Corporation. The complete membership list can be found here.

Q. What is Solid State RF Energy? What are the Applications for this technology?

SSRFE uses semiconductor technology to generate powerful RF fields, in contrast to legacy tube-based technology such as magnetrons, which can generate the power, but lacks controllability. SSRFE-driven applications benefit from very agile control and feedback of electromagnetic fields (frequency, phase, power level, on/off can be changed within a microsecond scale). 

Applications that benefit from the unprecedented, effective and highly efficient control of SSRFE technology include consumer and industrial cooking, industrial lighting, plasma and heating, automotive ignition and medical devices for ablation, hyperthermia treatment and imaging.

Q. What are the Advantages of Cooking/Heating Using Solid State RF Energy Technology over the existing technology (magnetrons)?

The magnetron lacks control compared to the precision of a SSRFE transistor. With the magnetron, absorbed energy cannot be discerned from reflected power, which makes it impossible to control the overall amount of energy delivered. Consequently, food is not uniformly cooked. The SSRFE transistor has the ability to tailor the frequency, phase and output power to suit cooking a specific food, or even multiple foods placed in the cavity.

There are many advantages to SSRFE technology over the magnetron for cooking applications. For more details, please see the Alliance’s new Solid-State RF Energy Infographic.

Q. What do you feel is holding this technology from being adopted at scale in Cooking Applications? What needs to be done to get it there? And, when do you expect to see main-stream commercial products based on this technology?

SSRFE for cooking applications is gaining industry momentum and a number of cooking solutions have already hit the market - as recently seen with the Dialog Oven announcement from Miele. However, challenges still remain for wide scale adoption in high-volume markets. The reasons often tie back to engineering complexity and system cost.

SSRFE system design requires specific engineering knowledge, which is not generally available due to RF (power) engineers being occupied with “linear amplifier” systems for data-transmission purposes or concerned with magnetron sources for heating applications. There is a general lack of design understanding with respect to applying and integrating solid-state RF generation to novel applications and systems.

Additionally, SSRFE applications are still quite expensive due to the current volume supply base. The RFEA’s efforts to develop specifications and roadmaps for SSRFE systems will combat these obstacles—and we believe it will make SSRFE mainstream. For example, the “RF Power Amplifier (PA) Roadmap: Residential Appliances” outlines multiple PA modules that feasibly reduce the system cost to be competitive with current magnetron-based solutions in the near future.   

Q. Apart from Cooking, can you give us a few examples where this technology has been used and how it is better than the conventional technology for the application.

SSRFE technology is being used in many applications spanning a variety of industries. For example, SSRFE is enabling advancements in plasma lamps, effectively extending the lamp’s energy efficiency and overall lifespan. This will have a significant impact in industrial scale horticulture, where SSRFE plasma lamps can create the most sun-like light spectrum – making it ideal for growing plants indoors. Furthermore, SSRFE technology is being applied to automotive ignition systems as a replacement for spark plugs, with studies showing impressive fuel savings and reduced emissions. SSRFE’s unprecedented control and precision of RF energy will also significantly advance a number of existing medical treatments and applications. For example, plasma scalpels can vastly improve patient recovery times after surgical procedures, which can be attributed to the precision cutting advantages not possible with metal scalpels.

Q. Both LDMOS and Gallium Nitride (GaN) Technologies have been used for RF Energy Applications. What is your view on these two technologies, can they co-exist? Is one technology better than the other for RF Energy Applications?

Currently, LDMOS is clearly the dominating technology for high-power RF applications. Based on silicon (Si), it enjoys the economy of scale processing available in large wafer fabs and, hence, allows the “niche” LDMOS technology to benefit from high-volume, low-cost fabrication. From a semiconductor standpoint (silicon), the material parameters are far less attractive than those of GaN. The latter, being a high-bandgap, direct III/V semiconductor, offers increased efficiency, higher temperature operation, much higher breakdown voltages (ruggedness), and higher carrier mobilities, which makes this material the ideal semiconductor for high-power, high-frequency (RF energy) applications. At this point, the GaN industrialization has not yet achieved the scale nor maturity to allow comparable cost levels as those of LDMOS. However, efforts are under way and the III/V material is clearly closing in towards LDMOS.

The above-mentioned performance/cost differences will also determine the use of either material in applications. The moment the application demands the best available efficiency or bandwidth, GaN will be the obvious choice. If it requires cost-effectiveness at decent performance, Si LDMOS wins. GaN holds a clear efficiency advantage above LDMOS at higher frequencies (915, 2.45GHz and above). This advantage is less obvious at frequencies between 100 to 434 MHz, but the proof of the pudding there is still out.

This “distribution” will stay unchanged until GaN can be processed at Si cost—recent advances in that respect (GaN-on-Si technology) may prove disruptive in the coming years, and could enable a whole new host of compact, efficient amplifiers driving new RF energy applications.

Click here to see a complete list of Transistors developed for RF Energy Applications.

Q. How many members does the Alliance have? Who should join the Alliance? What are the advantages of becoming a member?

Currently, the RFEA has twenty-four members. The Alliance is comprised of three membership levels: Promoter, Contributor and Associate. Companies ranging from OEMs and component suppliers to service providers and institutions dedicated to the Alliance’s mission are encouraged to join. For information about membership levels and instruction on how to join, visit

Members will have more or less direct access to the proceedings of different technical committees and will be able to define subjects for technical committees. Access and contribution permissions are dependent on membership levels.

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Click here to view the database of RF Transistors developed for RF Energy Applications.