Reliable and Efficient Microwave Circuits for Space Applications

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