Research And Design Of Bandpass Filters Using LC Resonators

With the rapid development of wireless mobile communication technology, the traditional front-end RF components design can not meet the demand of mobile communication systems for components today. The multilayer media design technology based on low temperature co-fired ceramic (LTCC, Low Temperature Co-fired Ceramic) has to offer mobile communication technology solutionsWe design and analyze the 3D(three dimensional)structural model of LTCC microwave filter by HFSS(High Frequency Structure Simulator).This thesis focuses on the design of second-order LTCC bandpass filter are investigated both numerically and experimentally. First, two novel filter structures of second-order bandpass filter with two transmission zeros are proposed. A filter is built on a pair of capacitive coupled resonator tanks with a feedback capacitor between input and output, introducing two transmission zeros; the other filter schema incorporates a grounding capacitor, connecting a pair of inductive coupled resonator tanks with the ground, to provide transmission zeros. Second, study of the filter change the value of various parameters on their characteristics and analysis of filter transmission zero. An equivalent lumped circuit is derived to explain the behaviors both graphically and mathematically of the two finite transmission zeros. Then, a simple design procedure for such two compact filters is also given. Finally, the analysis of both advantages and disadvantages of second-order band-pass filter, and pointed out their general application scenarios.Compared to traditional domestic microwave bandpass filter, the design in this thesis of microwave bandpass filter of second order not only has a small, compact, flexible design characteristics, and low in-band insertion loss and can get a better frequency selectivity and anti-electromagnetic interference, by adjusting the out-band transmission zeros, more in line with the application of modern mobile communications prospects. These works may be effective for engineering use.