Reliable and Efficient Microwave Circuits for Space Applications
Abstract: In this thesis, reliable and efficient microwave circuits used in space applications, e.g. satellite transponder systems, are discussed. The main focus is on mixers, multipliers and power amplifiers. A novel Zero Bias Diode (ZBD) is proposed and investigated. The new diode design offers higher reliability and can operate with lower LO power compared to ordinary gate-Schottky diodes. Furthermore, MMIC mixers based on the ZBD are designed and characterized. A new high efficiency balanced multiplier topology is also presented. High efficiency is obtained by forcing the transistor to operate in deep class C by a source RC bias circuit. The principle of operation is demonstrated in a commercially available MMIC mHEMT process. An overall efficiency of almost 15 % is obtained with the new multiplier topology. The last part of this thesis deals with efficient power amplifiers, e.g. Class D, E and F. A class E amplifier operating at 1 GHz is implemented with state of the art results. Moreover, two inverse class F PAs operating at 1 GHz and 1.8 GHz respectively are designed and characterized with very good results.
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