Integration Of Ltcc Millimeter-wave Transmission Line Transition And The Parasitic Mode Of Analysis And Modeling

With the rapid development of the millimeter-wave technology, the requirement of miniaturization, low cost, reliability and volume production of equipments and products is increasing. LTCC (Low Temperature Co-fired Ceramic) technology has its strong advantages in this area. Using LTCC technology can realize the design of mixture of microwave and millimeter-wave transmission lines such as microstrip, stripline, coplanar waveguide, and DC signal lines, which can greatly improve the density of millimeter wave circuit and module. However, in the millimeter-wave integrated circuits, in particular in LTCC multilayered structures, transmission line and its interconnection or transition has always been an important factor of constraining the development of integrated technology. Its transmission characteristics and electromagnetic transmission performance directly affect the RF performance of other LTCC components, circuits, modules as well as the whole system. Therefore, our study on the transmission performances and transitions of millimeter-wave transmission lines of LTCC will have important practical significance.The dissertation focus on the interconnections including the vertical transitions and coplanar transitions of millimeter-wave transmission lines of LTCC, as well as parasitic modes which have a significant impact on transmission circuits. Firstly, it mainly focus on all kinds of transition structures of the most commonly used transmission lines such as microstrip, stripline and coplanar waveguide in mm-band LTCC multilayered substrate structure, and presents seven vertical and coplanar transition models. And then, the article analyzes how to use the metal-filled via holes to improve the transmission performance of transitions and suppress parasitic effects. Simulation results and measured results have been performed to validate the feasibility of these transitions, which could offer design datas and reference models for the Ka band applications of LTCC.The electromagnetic field parasitic modes in LTCC structures have been investigated systematically in this dissertation, and the concept of parasitic mode has been proposed, as well as a variety of parasitic mode types have been summarized. The dissertation also expatiates and analyses many kinds of electromagnetic field parasitic modes in LTCC in detail for the first time, and derives the parasitic mode types, excitation mechanism and propagation characteristics according to the relevant theory and formulas, and explores the impacts on the circuits and its suppression methods. Specific analysis models have been constructed by three-dimensional electromagnetic filed simulator HFSS, and parasitic surface wave mode and parallel plate waveguide mode have been discussed in detail. Result parameters and field distribution graphs have been extracted through the powerful modeling and data functions of the software to analysis propagation characteristics and impacts of the parasitic mode qualitatively and quantitatively. At last, corresponding suppression structures of parasitic modes have been designed and validated, the measurement verifies the feasibility of the models.These structures coulde be used in the practical LTCC circuits in order to improve the RF performance of millimeter wave integrated circuits.