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

Lead Research Organisation: University of Manchester
Department Name: Electrical and Electronic Engineering

Abstract

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.

Publications

10 25 50
 
Description The research has identified and devised techniques to operate power semiconductor devices at switching frequencies in the range 50 MHz to 100 MHz. This represents an increase of around one hundred times over typical operating frequencies. This increase in frequency will enable the power supply circuits for RF power amplifiers to provide a rapidly changing output voltage to the amplifier, resulting in an overall increase in system efficiency. The research has identified the most suitable converter topologies, gate drive circuits and control methods, with the multi-level approach offering distinct advantages. The results of the modelling and simulation work have been validated with off-the-shelf semiconductor components. In the final phase of the work custom designed devices will be fabricated by Sheffield University. The research is also investigating the interactions between the power supply and the RF amplifier . A number of unexpected patterns of behaviour have been identified and analysed, enabling the development of an overall system design and optimisation methodology, which will be demonstrated in the closing stages of the project.
Exploitation Route The most immediate applications will be in the next generation of mobile communications systems (5G), but more generally the techniques will also have applications in low-voltage power conversion systems where high performance (high efficiency and small size) are priorities. This includes the power supplies for many electronic devices and systems and potentially wireless charging systems.
Sectors Aerospace, Defence and Marine,Digital/Communication/Information Technologies (including Software),Electronics,Energy,Transport

 
Description KTP
Amount £240,146 (GBP)
Funding ID KTP11288 
Organisation TT-electronics Semelab 
Sector Private
Country United Kingdom
Start 05/2019 
End 04/2022
 
Description KTP
Amount £240,146 (GBP)
Funding ID KTP11288 
Organisation Innovate UK 
Sector Public
Country United Kingdom
Start 05/2019 
End 04/2022
 
Description Envelope tracking consortium 
Organisation Cardiff University
Department School of Engineering
Country United Kingdom 
Sector Academic/University 
PI Contribution Provided understanding of the characteristics and performance limits of power converter circuits, including the impact of semiconductor device characteristics on system performance, and how best to design / control a converter to achieve the required envelope tracking performance.
Collaborator Contribution Development of optimised power semiconductor devices for very high frequency operation in a power converter (Sheffield) and an understanding of the performance requirements and trade-offs in envelope tracking applications (Cardiff).
Impact Too early for outcomes to have materialised.
Start Year 2017
 
Description Envelope tracking consortium 
Organisation University of Sheffield
Department Faculty of Engineering
Country United Kingdom 
Sector Academic/University 
PI Contribution Provided understanding of the characteristics and performance limits of power converter circuits, including the impact of semiconductor device characteristics on system performance, and how best to design / control a converter to achieve the required envelope tracking performance.
Collaborator Contribution Development of optimised power semiconductor devices for very high frequency operation in a power converter (Sheffield) and an understanding of the performance requirements and trade-offs in envelope tracking applications (Cardiff).
Impact Too early for outcomes to have materialised.
Start Year 2017
 
Description Hosting summer student interns 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Undergraduate students
Results and Impact Hosted two undergraduate student interns in the research group who worked on aspects of this research project. This enabled them to learn about research work and research careers in general and about the specific challenges and technology in this project.
Year(s) Of Engagement Activity 2019
 
Description Poster presentation at EPSRC Power Electronics Centre annual conference 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact Poster presentation by the project RA Alejandro Villarruel to raise the profile of the research within the community and highlight the achievements.
Year(s) Of Engagement Activity 2019
 
Description Wireless Power Week Discussion Panel 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Presentation and panel discussion on wide band-gap power device applications held at Wireless Power Week 2019. An IEEE / IET conference held at Savoy Place, London.
Year(s) Of Engagement Activity 2019