1.45GHz-1.55GHz Tunable RF Band-pass Filter

RF signals are used in the communication field in general. It has special band called microwave band which is the focus of this project. The idea of filtering comes from the need to transmit certain frequency of ranges of interest and block others. In this project the focus is on tunable filters using MEMS idea to solve the problem of complexity and price of the conventional tunable filters. The project focuses on L band to get the range from 1.45GHz to 1.55 GHz. The project starts by designing the low pass prototype and convert it to comb-line filter to find the capacitance range for the design of the tuneable capacitor using CMOS-MEMS technology. The tunable capacitor has to be modelled and designed. Theoretical modelling and ADS simulation determined the tuning range required for the capacitor is from 1.72pF to 1.84pF. A CMOS-MEMS fixed and tuneable capacitors were designed and simulated to achieve this range of capacitance and requires a voltage of 20V for tuning. Thus the objectives of the study have been achieved successfully and recommendations are made to achieve a wider frequency range for the filter and for integration of the filter with the tunable capacitor.