Paul J. Tasker

Paul J. Tasker (M’88–SM’07) received the B.Sc. degree in physics and electronics and Ph.D. degree in electronic engineering from Leeds University, Leeds, U.K., in 1979 and 1983, respectively. From 1984 to 1990, he was a Research Associate with Cornell University, Ithaca, NY, USA, where he was involved in the early development of HFET transistors. From 1990 to 1995, he was a Senior Researcher and Manager with the Fraunhofer Institute for Applied Solid State Physics (IAF), Freiburg, Germany, where he was responsible for the development of millimeter-wave monolithic microwave integrated circuits (MMICs). In the summer of 1995, he joined the School of Engineering, Cardiff University, Cardiff, U.K., as a Professor, where he has been establishing the Cardiff University and Agilent Technology Centre for High Frequency Engineering. The center’s research objective is to pioneer the development and application of RF I–V waveform and engineering systems with a particular focus on addressing the PA design problem. He has contributed to over 200 journal and conference publications. Dr. Tasker was an IEEE Distinguished Microwave Lecturer (2008–2010). He has given a number of invited conference workshop presentations.

Microwave power amplifier performance, output power, conversion efficiency and linearity, etc., is significantly influenced by the terminal voltage and current time varying waveforms that develop at the transistor terminals; terminal waveforms are the unifying theoretical link between transistor technology, circuit design and system performance. Thus waveform engineering should be a major objective driving the power amplifiers design flow. However, in practice power amplifier design, while waveform engineering may be a guiding principle, the lack of appropriate RF waveform measurements tools has hindered its direct application at microwave frequencies. However, the past 10 years has seen the development of a number of RF characterization systems capable of measuring RF voltage and current waveforms. Coupling such systems with impedance control hardware also enables experimental control (Engineering) of these terminal RF waveforms during measurements; thus providing a practical RF Waveform Measurement & Engineering solution. This lecture will discuss these emerging systems and show they are now finally enabling practical waveform engineering to be directly undertaken within the power amplifier design flow. Design support can involve either direct utilization of the measurement system in the design investigation/evaluation loop, or indirect use by providing CAD accessible datasets.