Microwave LTCC Modeling Key Technology

Nowadays, as the most potential technology of MCM(Multichip Module),LTCC(Low Temperature Co-fired Ceramic) has been the hot topic and main trend in thedevelopment of high-speed and high-integrated technology research. Today, microwaveLTCC processing line has been established in China. However, modeling and databaseof LTCC is not systematically established, which increases period and cost of itsresearch, thus influencing the extend and application of LTCC technology.This thesis comes from modeling and database-creating of the project MicrowaveLTCC Design Plat. In it, LTCC layer to layer interconnect structures of differenttransmission lines and LTCC multilayer filters are researched and then modeled. Theaim of this thesis is:1.Establish a broadband and excellent-property layer to layerinterconnects’ model;2.Establish a LTCC multilayer filters’ model which can instructusers to design LTCC multilayer filters based on their index. The main research contentis as follows:1. Adopting the theories of4port directional coupler and coupled lines, physicalmodels of CPW(Coplanar Waveguide) and MS(Micro-strip Line), and their owncoupling interconnects are proposed. The influence of their coupled section’ s physicalparameters to their microwave properties is researched. By simulating and optimizing,the final structures which have return loss below15dB in the range from5GHz to12GHz are obtained.2. Adopting the theories and prototype of low pass filter, physical models of LPF(Low Pass Filter), including stepped-impedance type low pass filter and open-circuitedstubs type low pass filter, and BPF (Band Pass Filter), including inter-digital filter andhairpin-line filter are proposed. Adopting the extraction method of the filters’ Q(externalquality factor) and M(coupling coefficient), inter-digital and hairpin-line band passfilters are proposed. The relationship of physical parameters of I/O and Q and therelationship of physical parameters of resonators and M are researched. By simulatingand optimizing, inter-digital band pass filters whose center frequency is2GHz andbandwidths are20%and10%and hairpin-line filters whose center frequency is5GHz and bandwidth is20%are obtained.3. Adopting Cauchy interpolation function method, model which indicates themapping relation between the interconnect structures’ physical parameters and its Sparameter, and between the filters’ physical parameters and Q and M is proposed.Matlab code aimed at synthesizing filters is programmed. By researching therelationship of modeling accuracy and Cauchy interpolation function step andrationality of the sample, model whose accuracy is above8%is obtained.4. Adopt Ferro A6M to process the LTCC layer to layer interconnects and LTCCmultilayer filters. Adopt Anristu3680test fixture to measure them. The error betweentesting results and simulating results is analyzed.