Integration of RF Circuits with High Speed GaN Switching on Silicon Substrates

Future generation (5G) mobile phones and other portable devices will need to transfer data at a much higher rate than at present in order to accommodate an increase in the number of users, the employment of multi-band and multi-channel operation, the projected dramatic increase in wireless information exchange such as with high definition video and the large increase in connectivity where many devices will be connected to other devices (called "The Internet of Things"). This places big challenges on the performance of base stations in terms of fidelity of the signal and improved energy efficiency since energy usage could increase in line with the amount of data transfer. To meet the predicted massive increase in capacity there will be a reduced reliance on large coverage base-stations, with small-cell base-stations (operating at lower power levels) becoming much more common. In addition to the challenges mentioned above, small cells will demand a larger number of low cost systems.

To meet these challenges this proposal aims to use electronic devices made from gallium nitride (GaN) which has the desirable property of being able to operate at very high frequencies (for high data transfer rates) and in a very efficient manner to reduce the projected energy usage. To maintain the high frequency capability of these devices, circuits will be integrated into a single circuit to reduce the slowing effects of stray inductances and capacitances. Additionally these integrated circuits will be manufactured on large area silicon substrates which will reduce the system unit cost significantly.

The proposed high levels of integration using GaN devices as the basic building block and combining microwave and switching technologies have never been attempted before and requires a multi-disciplinary team with complementary specialist expertise. The proposed consortium brings together the leading UK groups with expertise in GaN crystal growth (Cambridge), device design and fabrication (Sheffield), high frequency circuit design and fabrication (Glasgow), variable power supply design (Manchester) and high frequency characterisation and power amplifier design (Cardiff). Before designing and developing the technology for fabricating the integrated systems to demonstrate the viability of the proposed solutions, a deep scientific understanding is required into how the quality of the GaN crystals on silicon substrates affect the operation of the devices. In summary, the powerful grouping within the project will bring together the expertise to design and produce the novel integrated circuits and systems to meet the demanding objectives of this research proposal.

The aim of the 3 year project is to deliver an integrated GaN-on-silicon RF and switching technology for emerging and future communications networks (4G/5G), imaging, radar and sensing applications. The project will deliver novel technology and design, enabling industry to develop new integrated systems for improved competitiveness leading to economic benefit to the UK. Social benefits will be felt by rural communities as the proposed technology will provide a higher range terrestrial communication network coverage and enhanced power transmission will enable cheaper satellite communication linking with remote areas for internet use. The research team has a strong track record of Knowledge Exchange and commercialisation, engaging with industry and other organizations over a period greater than 30 years.

Project partners Oxford Instruments, IQE, NXP, Plessey, Selex, MACOM, NewEdge Signal Solutions (Nujira), Arelis (Thomson Broadcast), Diamond Microwave Devices (DMD), Rohde & Schwarz, DSTL, ESA and KNT represent a broad spectrum of applications developers and end users; covering telecommunications systems development, RF component development, semiconductor manufacturing, wafer suppliers, defence and space applications. These companies are likely to benefit from the research through access to emerging new technologies and designs. Many are committed to direct support through technology evaluations and to be part of the technology transfer process by outlining their requirements and challenges and adopting the technology (license) to take it to market within a ten year time scale. To achieve impact we will work with our partners to develop the technology to a suitable TRL, demonstrate its applications in different fields and transfer the technology. We will work with the key partners to scope out KE/development projects using studentships, Knowledge Transfer Partnerships, PDRA secondments and making use of the funding sources such as Impact Acceleration Accounts, Knowledge Exchange Fund, Innovate UK and Horizon 2020.