Tunable frequency resonator design and realization

Abstract

Oscillators are used to generate microwave signals in many electronic circuits in communication systems. Voltage controlled oscillators are also frequently found in electronic circuits. Resonance frequency is the determining factor of frequency band in oscillator constructions. Basically, when the resonance frequency of resonators can be adjusted by current or voltage control, then these resonators can be used in oscillator circuits instead of other structures mentioned in the literature. It has been foreseen in many studies that the resonance frequency and other factors affecting performance can be improved by the help of metamaterials’ special properties and design variety. In this study, the design, manufacture and characterization of three resonator structures have been realized with the aim of obtaining tunable resonance frequency. In the first phase of the study; resonators are designed by examining the frequency effect of the results of capacitance variation obtained by conformal mapping and the other calculation methods of passive circuit elements. Three series of resonators were produced up to a certain stage using photolithography, nickel electroplating, metal sputter, selective wet etching and other auxiliary microfabrication processes. The fabricated resonators were characterized under magnetic excitation and without magnetic excitation. It was determined that the frequency was reduced by the applied magnetic force in the second series design. It is seen that the frequency in the steel resonator can be adjusted by 4.7 % with the applied voltage. The voltage and current were changed linearly and the resonator was characterized by measuring the displacement of the split cantilevers from their tips. 16 µm displacement of the tip of the cantilever results in 4.7% amount of frequency change.