Gallium nitride based transistors for high-efficiency microwave switch-mode amplifiers [Elektronische Ressource] / vorgelegt von Stephan Maroldt

Gallium Nitride Based Transistors for High-Efficiency Microwave Switch-Mode Amplifiers Dissertation zur Erlangung des Doktorgrades an der Technischen Fakultät der Albert-Ludwigs Universität Freiburg im Breisgau vorgelegt von Dipl.-Ing. Stephan Maroldt Juni 2010 Dekan: Prof. Dr. Hans Zappe Referent: Prof. Dr. rer. nat. Oliver Ambacher Koreferent: PD Dr.-Ing. habil. Frank Schwierz Datum der Prüfung: 11.11.2010 II Abstract Highly-efficient switch-mode power amplifiers form key elements in future fully-digital base stations for mobile communication. This novel digital base station concept reduces system energy consumption, complexity, size and costs, while the flexibility in terms of multi-band operation and signal modulation improves. In this work, innovative core circuits for digital high-efficiency class-D and class-S power amplifiers based on gallium nitride (GaN) technology were developed for the application in digital base stations. A combination of optimized GaN devices and improvements in circuit design allow a highly-efficient switch-mode operation at mobile communication frequencies between 0.45 GHz and 2 GHz. Transistor device modeling for switch-mode operation, the simulation environment, and a broadband measurement system were established for the design and evaluation of digital switch-mode power amplifiers.