Welcome from our CEO, Simon Mead

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

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.

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.

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.

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.

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

Closing remarks and event ends