Design of tunable oscillators

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Mészáros Gergely Zoltán
Department of Broadband Infocommunications and Electromagnetic Theory


In this thesis design and implementation of tunable microwave oscillators based on Infineon’s BFP405 RF bipolar juncion transistor with 1600-2000 MHz bandwidth have been prsented. In the first chapter summarizes the basic theory of oscillators including operation priciples, features of the microstrip transmission line and two types of microwave oscillator circuits (BJT oscillator with feedback, two-port negative resistance oscillator). AWR Design Environment 2009 software has also been summarized briefly. The next chapter to initially simulate analysis and to demonstrate the design methods, I have designed several circuits with feedback on the Arlon 25N substrate with 2 GHz operating frequency; then the results of transmission and spectral simulation are presented. Further on I studied the oscillating behaviour of load of the negative resistance oscillator and terminating network based on Rogers RO4003c substrate. Next I analyse (Skyworks SMV 1249) simulated tuning effect of the varicap diode (Skyworks SMV 1249) on output harmonics of oscillators (feedback and negative resistance). After the simulations I present the ralization steps of the tunable oscillators. After having all measurement results of the output spectra and tranmission of the filter, they will be compared to the simulated characteristics. In the last part of my thesis I draw my conclusion about the implementations and the measurement results, and I review the design procedure.


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