Compact LTCC Filtering Power Splitting Circuits Design

Recently, with the rapid development of wireless communication and mobile communication system, the demands of the circuit system are tend to miniaturization, lightweight and high integration. To achieve this, a lot of scheme was proposed. Among them, the new design ideas and the use of new technology are two main directions. Integrated design and LTCC(Low Temperature co-firing Ceramic) technology are two commonly used and effective way to meet the demands. This paper presents the integrated design of passive components with filtering responses using these two methods. The main work can be summarized as follows in three parts:1. Balun filter using folded half-wavelength resonators and broadside coupling. In this part, differential filtering networks are realized by the standing-wave property and phase characteristics of the half-wavelength resonators. Taking full advantages of the 3-D structure, common resonator, broadside coupling are used. The circuit is analyzed, simulated and measured. This work has been published in IEEE, 2015 international wireless symposium.2. LTCC in-phase and out-of-phase filtering power divider. In LTCC power splitting circuit, most of them are consisted of quasi-lumped elements, few research focus on using the coupling between distributed resonators. Based on the previous balun filter,we also use the characteristics of the half-wavelength resonator and further improve the circuit. The article gives the equivalent circuit principle diagram and analysis based on the theory of transmission line. Comparisons of the measured and simulated results are also presented to verify the theoretical method. This work has been submitted to IEEE Transactions on Industrial Electronics。3. LTCC filtering rat-race hybrid with wide stopband and LTCC filtering rat-race hybrid using 3-D coupling structure. In the first circuit, quasi-lumped elements are used to design LTCC circuit. The article proposed a kind of structure with can broaden the stopband as well as realizing filtering responses. By using the stricture to replace the quarter-wavelength and three quarters transmission lines in conventional rat-race hybrid, the characteristics of rat-race hybrid and filter are realized simultaneous. The second circuit using common resonator and broadside coupling to design a filtering rat-race hybrid in 3-D structure. Comparing with the planar circuit, only four resonators are needed instead of eight. In both design, simulation and measurement are given in the article to verify the proposed theory.