Breakthrough in Semiconductor Technology Sets New Efficiency Record for Broadband Satellite Communications

Future global communication networks that also cover remote regions, withstand potential sources of interference, and can step in during disasters, must be able to reliably process high data rates. High-throughput satellites (HTS) in low Earth orbit (LEO) and/or geostationary orbit (GEO), which use the broadband Ka-, Q-, and W-frequency bands and follow strict modulation schemes, offer a promising option for implementing such networks. The hardware required for such communication systems, active antennas for electronic beam steering, relies on extremely efficient power amplifiers with high linearity. 

The compactness required for active antennas causes thermal problems with existing components. Researchers at the Fraunhofer Institute for Applied Solid State Physics IAF have therefore developed high electron mobility transistors (HEMTs) based on the wide bandgap compound semiconductor gallium nitride (GaN), which have a gate length of only 70 nm. The measured efficiency values demonstrate the great potential of this innovative technology for future applications in satellite communications.

Components for broadband satellite communication

“Thanks to their high linearity and efficiency, the GaN power amplifier HEMTs developed at Fraunhofer IAF enable more compact and energy-efficient communication systems for satellites. With our innovative technology, we are making an important contribution to the establishment and expansion of seamless and resilient global communication networks,” explains Dr. Philipp Döring, scientist in the Technology Department at Fraunhofer IAF and lead author of the research paper presenting the 70 nm GaN HEMTs.

Dr. Döring will present the paper “High efficiency and high linearity 70 nm GaN technology for future SatCom applications” on September 23 from 2:10 p.m. to 2:30 p.m. at the European Microwave Integrated Circuits Conference (EuMIC) in Utrecht, Netherlands. EuMIC is part of European Microwave Week (EuMW).

70 nm GaN transistors with record efficiency

The GaN HEMTs were developed, manufactured, and characterized in the in-house semiconductor line in the Epitaxy, Technology, and Microelectronics departments at Fraunhofer IAF. The GaN/AlGaN (aluminum gallium nitride) semiconductor material system was grown on semi-insulating 4-inch silicon carbide (SiC) substrates using metal organic chemical vapor deposition (MOCVD). Processing was carried out using electron beam lithography, among other methods. 
The researchers performed test measurements on individual transistors as well as directly on the wafer. In small-signal measurements, a cut-off frequency of fT = 122/95 GHz and a maximum frequency of fMAX more than 350 GHz were determined at VDS of 7/15 V. Load-pull measurements yielded a maximum power-added efficiency of 58.6% and a maximum output power of 2.46 W/mm at 38 GHz on 8×60 µm transistors.
To determine signal linearity, the researchers used a two-tone load pull method to test which of the 70 nm GaN HEMT meet the requirements currently specified by the European Space Agency (ESA) for satellite communications. Under the boundary condition of IMD3 ≥ 30 dBC, the technology achieved an efficiency of PAE = 54.4% and an output power of 1.01 W/mm. This is the highest efficiency value ever measured for a GaN technology at 30 GHz.

Technology development in the context of the Magellan and GANYDEM170 projects
The results were obtained as part of the Magellan and GANYDEM170 projects. Magellan is funded by ESA and aims to develop highly efficient millimeter-wave GaN high-power amplifiers for GEO and LEO active antenna applications. GANYDEM170 is funded as an IPCEI (Important Project of Common European Interest) by the German Federal Ministry for Economic Affairs and Energy (BMWE) and enables the realization of an industry-ready millimeter-wave GaN technology for metrology applications.

Fraunhofer IAF at EuMW 2025

At EuMW 2025, which will take place from September 21 to 26 in Utrecht, Netherlands, Fraunhofer IAF will present further research results from the field of GaN-based high-frequency electronics in addition to the findings of Dr. Philipp Döring. On the one hand, the institute will exhibit a wide selection of components, circuits, and modules at booth B071 at the trade fair. On the other hand, Patrick Umbach, Thomas Zieciak, Moïse Safari Mugisho, and Dr. Philipp Neininger will give presentations at EuMIC. In addition, the institute’s director, Dr. Patricie Merkert, will participate in the EuMIC Foundry Panel, where she will talk about monolithic and heterogeneous integration as well as chiplets.

Overview of all presentations by Fraunhofer IAF

EuMIC04-5 – Monday, September 22, 12:10–12:30
Patrick Umbach: Monolithic Integrated Broadband IF Balun and LO Amplifier

EuMIC06-4 – Monday, September 22, 14:50–15:10
Thomas Zieciak: A 200 mW, high-gain GaN-based D-Band Power Amplifier for 6G Communication Applications

EuMIC10 – Monday, September 22, 16:10–17:50
EuMIC Foundry Panel mit u. a. Dr. Patricie Merkert 

EuMIC11-5 – Tuesday, September 23, 9:50–10:10
Moïse Safari Mugisho: A V-Band (61–72 GHz) GaN HEMT High-Power Amplifier

EuMIC14-2 – Tuesday, September 23, 14:10–14:30
Dr. Philipp Döring: High efficiency and high linearity 70 nm GaN technology for future SatCom applications

EuMIC/EuMC03 – Halle 7 | 1-Minute Poster Pitch – Media Arena, 9:30–10:10
Dr. Philipp Neininger: An Integrated W-Band Dual-Polarization Receiver Front-End Featuring Ultra-Low Noise Figure