Edward C. Niehenke, P h.D., PE, Consultant, Baltimore, Maryland, USA. Niehenke has pioneered the development of state-of-the-art RF, microwave, and millimeter wave components at Westinghouse/Northrop Grumman for 34 years. Circuits include low noise amplifiers, low noise oscillators, mixers, power amplifiers, phase shifters, attenuators, limiters, frequency multipliers, low-phase noise millimeter wave fiber optical links, and miniature integrated assemblies and subsystems. He previously worked in cryogenic electronics research at Martin-Marietta. He now consults and lectures on linear/nonlinear and wireless transmit/receive circuits and systems. Since 1983 he lectured to over 3000 professionals throughout the world for Besser Associates and the Continuing Education of Europe. He holds nine patents, one George Westinghouse Innovation Award, and has authored and presented numerous papers on RF, microwave, and millimeter wave circuits.
This lecture introduces attendees to the GaN-transistor, its properties, various structures, including the latest GaN power amplifier (PA) design techniques. The properties of GaN will be presented showing the advantage of these devices over GaAs and Si. GaN HEMT transistors will be shown delineating the various geometries, semiconductor processes and structures with associated performance. Guidelines for reliable operation will be presented considering device junction temperature including thermal management techniques. The nonlinear models of GaN HEMT devices necessary for the CAD of PAs will be presented. Design considerations for both constant amplitude envelope signals as well as the non-constant amplitude envelope signals will be presented. Step-by-step design procedures will be shown for various GaN PA examples including different classes of operation as well as the popular Doherty PA.