Study On The Technique For Stacked-Multistage Cascaded LC Band-pass Filters On Multilayer Substrates

Microwave or RF filters are very important components in wireless communication systems,whose performance will directly affect the overall system performance. The multilayer dielectricstructure can not only effectively reduce the size of the components to improve the integration ofpassive microwave devices, but also can be more convenient coupling capacitance and inductancebetween layers in order to add the attenuation poles by cross-coupling technology to improve theperformance of the filter. This thesis studies the multilayer-dielectric band-pass filter, and furtherstudies multistage-cascade band-pass filter. The main job and innovations are as follows:(1) Analyzing the performance of the second-order band-pass filter.(2) Designing a cascading form of fourth-order band-pass filter structure. Two attenuationpoles are added to stop-band of both sides. Then the attenuation characteristics of the stop-band canbe significant improved without affecting the passband insertion loss.(3) We can effectively achieve the coupling between the resonant units by increasing acapacitance to ground which is parallel with the resonant units. Then the performance of thefourth-order band-pass filter can be improved greatly.(4) Discussing the parameters affecting the filter's performance. Summing up the best designof the band-pass filter with the structure of the multilayer dielectric.At present,the designing and analysis of multilayer dielectric structures are mostly confined tothe second-order filter prototype whose stop-band attenuation is about only -20dB, while thefourth-order band-pass filter in this thesis performs effectively with the transmission zeros increasedin stop-band so that the attenuation can reach to -70 dB or so.