The care and feeding of GaN RF power amplifiers

Brought to you by The Radio Technology Group

This event from the Radio Technology SIG will introduce the new generation of RF power devices based on GaN and their use for applications covering the 5G spectrum.

About the event

This Deep Tech Talk will introduce the new generation of RF power devices based on GaN and their use for applications covering the 5G spectrum.

The talk is in two parts, with the first covering the large signal RF device characterisation of GaN HFETs.  Large signal engineered CW I-V Waveforms will highlight the device advantages for high power RF, as well as pointing out present technology limitations.  Link with design will be highlighted via measurement based behavioural models.  Emerging modulated characterization solutions, targeting trapping/memory concerns, will be introduced. 

The second part deals with the application of these devices to 5G power amplifiers, explaining the design approach, then demonstrating the performance with the high peak-to-average modulation used in 5G.

This talk will be useful to all engineers working on RF power amplifiers, and particularly those involved in 5G, from equipment design through to site commissioning.

We have limited FREE delegate places for those under 35, and for those working in start-ups and small organisations (less than 5 employees). To claim you free ticket please email clare.kettle@cambridgewireless.co.uk 

You can follow @CambWireless on Twitter and tweet about this event using #RadioTech.

Agenda

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The information supplied below may be subject to change before the event.

14:00

Welcome from our CEO, Simon Mead

14:03

Introduction from Chair, Professor Mark Beach, University of Bristol & Radio Technology SIG Champion

14:05

Professor Paul J Tasker, Cardiff University

'RF Waveform Characterization of RF GaN Transistors'

RF GaN transistors are emerging as the technology of choice for a broad range of security and communications applications covering frequency from RF thru to mm-wave requiring high RF power. This presentation will introduce Continuous Wave RF Waveform Engineering measurements systems. It’s utilization for both GaN HFET technology optimization, addressing issues such as knee walkout, and GaN HFET power amplifier design innovation, application of harmonic matching and continuous modes for high efficiency operation, will be covered. To conclude the link with CAD design will be highlighted via measurement based behavioural models.

14:30

Professor Johannes Benedikt, Cardiff University

'DC and RF-pulsed N-tone characterisations of RF GaN devices'

A key challenge with RF GaN technology is its slowly varying behaviour introducing distortions within the envelope of the transmitted signal at time constants ranging from less than a microsecond to tens of milliseconds. The interaction between such a highly dynamic device behaviour and the modulated RF signal poses a characterisation challenge that limits the understanding and modelling of this technology. The presentation will be focusing on an emerging measurement solution that is based on DC and RF-pulsed n-tone waveforms with the capability to capture time-varying signal distortions at power levels less than -60dBc and a time resolution of few nanoseconds.

14:55

Professor Kevin Morris, University of Bristol

'The use of GaN devices for Broadband, Efficient and Linear RF Power Amplifiers'

Gallium Nitride (GaN) devices have enabled the design of broadband, linear and efficient power amplifiers. GaN devices with their higher breakdown voltages and higher input and output impedances expand the design space to make use of more efficient and wideband amplifier classes. This presentation will look and how broadband amplifier designs can be combined with linearisation techniques to create amplifiers that can meet both the linearity and efficiency requirements for future systems. The talk will also look at how this is developing with the move to the emerging GaN on diamond technology.

15:20

Dr Tommaso Cappello, University of Bristol

'Bridging the gap between device and circuit characterization in RF power amplifiers'

RF power amplifiers based on GaN transistors are mainly degraded by thermal and trapping phenomena. Starting from low-frequency I/V measurements of two comparable GaN-on-SiC transistors (Qorvo vs. Wolfspeed), performance degradation of a RF power amplifier is evaluated for different classes of operation, i.e., class-A to class-E. The double pulse technique typically used in IV measurements is then applied at PA level to quantify the backoff gain reduction that can be associated with knee-walkout and current collapse in the transistor. By leveraging on this double-pulse characterization, trap release time constants are extracted and used to improve digital pre-distortion (DPD) linearization in the backoff region. Finally, a low-complexity behavioural model capable to estimate the transistor channel temperature is presented.

15:45

Panel session with all speakers chaired by Mark Beach, University of Bristol & Radio Technology SIG Champion

16:00

Closing remarks and event ends

Speakers

Johannes Benedikt - Professor, School of Engineering, Cardiff University

Johannes Benedikt received the Dipl.-Ing. Degree in electrical engineering from the University of Ulm, Germany in 1997 and shortly after he started a PhD course at Cardiff University. During his PhD project he developed a £0.5M research project with Nokia on RF power amplifiers and took on the position of senior research associate at Cardiff University starting at October 2000. He was awarded a PhD degree in 2002 and was appointed as a Lecturer in 2004 and a Senior Lecturer from August 2009. Following his success in research and engagement activities with industry he was awarded a personal chair in May 2010. He has a strong industrial background which he acquired in the last 10 years working together with DaimlerChrysler, Siemens, Robert Bosch, Nokia, Agilent, and Tektronix. His industrial involvement and inventiveness is underlined by three internationally granted patents, all submitted during his work with Cardiff University. Since April 2009 he took on in addition the position of a CTO at Mesuro Ltd, leading the commercial introduction of new measurement solutions that enable systematic waveform engineering at RF and microwave frequencies.

Tommaso Cappello - Lecturer, University of Bristol (Communication Systems & Networks Research Group)

Tommaso Cappello received the Laurea degree (cum laude) in electrical engineering and the Ph.D. degree from the University of Bologna, Italy, in 2013 and 2017, respectively. Since 2020, he is a Lecturer in Electrical and Communication engineering at the University of Bristol, UK. Between 2017 and 2019, he was a Post-doctoral Research Associate with the Microwave and RF Research Group at the University of Colorado Boulder, CO, USA. His current research interests include RF and power electronics and digital signal processing techniques for high-efficiency transmitter applications.

Kevin Morris - Professor of Radio Frequency Engineering, University of Bristol (Communication Systems & Networks Research Group)

Kevin Morris received the B.Eng. and Ph.D. degrees in electronics and communications engineering from the University of Bristol, Bristol, U.K., in 1995 and 2000, respectively. He is currently a Professor of Radio Frequency engineering and currently the Head of the Communications Systems and Networks Group (CSN) at the University of Bristol. He has authored or co-authored over 100 academic papers and he holds five patents. His research interests principally concern looking at methods of reducing power consumption in communications systems with a specific interest in the design of efficient frequency flexible transceivers. He is currently involved with several Engineering and Physical Sciences Research Council (EPSRC) research projects, most recently the Secure Wireless Agile Networks (SWAN) project and several industry funded research programmes within the U.K. He was Head of the Department of Electrical and Electronic Engineering from 2014 to 2018. 

Paul Tasker - Professor, Cardiff University

Prof. Paul J Tasker joined Cardiff University in 1995. His research addresses the problems encountered in the field of non-linear RF and microwave circuit design. These activities have, to date, focused mainly on the design, modelling and characterisation of non-linear RF and microwave transistors and power amplifier circuits. Paul has expertise in the area of fabrication, design and characterisation of high frequency (microwave and millimeter wave) compound semiconductor electronic and optoelectronic devices and circuits. He has developed a number of microwave and millimeter wave, s-parameters, noise parameters and non-linear parameter, measurement systems along with the associated analysis and extraction techniques for characterising transistors and developing CAD models. As a consequence of this work he has contributed to over 100 technical papers and publications including two book chapters.

SIG Champions

Mark Beach - Professor of Radio Systems Engineering, University of Bristol (Communication Systems & Networks Research Group)

Mark Beach received his PhD for research addressing the application of Smart Antenna techniques to GPS from the University of Bristol in 1989, where he subsequently joined as a member of academic staff. He was promoted to Senior Lecturer in 1996, Reader in 1998 and Professor in 2003. He was Head of the Department of Electrical & Electronic Engineering from 2006 to 2010, then spearheaded Bristol’s hosting of the EPSRC Centre for Doctoral Training (CDT) in Communications . He is the Co-Director of this centre. He leads research in the field of enabling technologies for the delivery of 5G and beyond wireless connectivity; which includes the recent award of an EPSRC Prosperity Partnership in the field of Secure Wireless Agile Networks (SWAN). Mark’s current research activities are delivered through the Communication Systems and Networks Group, forming a key component within Bristol’s Smart Internet Lab. He has over 30 years of physical layer wireless research embracing the application of Spread Spectrum technology for cellular systems, adaptive or smart antenna for capacity and range extension in wireless networks, MIMO aided connectivity for through-put enhancement, experimental evaluation and optimization of Massive MIMO, Millimetre Wave technologies as well as flexible RF technologies for SDR modems. With a strong industrially focused research portfolio, he is also the School Research Impact Director. 

Brian Collins - Managing Consultant, BSC Associates

Brian has designed antennas for applications including radio and TV broadcasting, base stations, handsets and consumer products, and has operated his own consultancy firm for the last 12 years. He has published more than 70 papers on antenna topics and contributed chapters to several recent textbooks. He operates a small consultancy company, chairs the Antenna Interface Standards Group and is an Honorary Visiting Professor in the School of Electronic Engineering and Computer Science at Queen Mary, University of London.

Vidhya Sridhar - Consultant, TTP plc

Vidhya Sridhar is a consultant at The Technology Partnership (TTP) Plc. She has a background in digital signal processing and physical layer design and development. In her PhD at Imperial College London, she carried out research on array signal processing techniques with applications in 5G and defence. Prior to her PhD, she spent three years working on physical layer design and development in LTE and WiMAX at Broadcom (India) and Alcatel Lucent (India) respectively.

Peter Topham - Principal Engineer, Qualcomm Technologies International

Peter has more than 30 years experience of RF and high-speed circuit design, taking chips into production ranging from FM Band II through cellular, Bluetooth and on to UWB at 10GHz. He has been with Qualcomm for 7 years, specialising in low-power RF design for portable and wearable products.

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