Design And Fabrication Of LC Bandpass Filters Constructed On Multilayer Substrates

Microwave and RF filters are widely used in various wireless communication systems, whichare important part of RF front device and have an effect on entire system. With the miniaturizationof communication components, the filter miniaturization becomes harder. Multilayer substratesstructure filter can take full advantage of the space-utilizing, reducing device size effectively, andmeet various demands. This thesis uses the multilayer substrates structure design the band-passfilter. It focuses on LC, which are lumped-parameter capacitor and inductor device, filter design andfabrication with the discussion of theoretical analysis and software simulation. The main work andcontributions of the thesis include:(1) The design of the fourth-order filter based on cascading two second-order units with animproved cascade method, thus the performance of this filter is improved without unnecessarycoupling.(2) A filter working at800MHz and having a bandwidth of15.4%is fabricated byhand-assembled the monolithic circuit units. The measurement result is in accordance with thesimulation results.(3) Keeping the insertion loss less than3dB, the filter bandwidth is reduced to2.7%insimulation and4.5%in fabrication in respectively.Actually filter design with multilayer substrates structure has been deeply studied and widelyused, however, there are a lot of unwanted coupling and parasitic between the various componentsof the multilayer dielectric structure. Thereby the filter performance is too poor to achievehigh-order filter. This thesis achieve a fourth-order filter using two second-order units. Meanwhilethe measurement shows high performance with a narrow bandwidth.