Design Of High Performance And Miniaturized RF Passive Devices

With the rapid development of the fifth generation(5G)wireless communication technology,the design of the new generation wireless communication system is facing extremely severe challenges.Lightweight,high performance,small size and low cost are the primary directions for the development of wireless communication systems.As important components of wireless communication systems,the performance and size of passive RF devices such as filters and couplers directly affect the communication quality and integration of the whole system.Therefore,how to design miniaturized,high performance and low-cost filters and couplers is particularly important,and is also the focus of both academic and industrial research.In this thesis,based on different application scenarios in the wireless communication field,multiple high performance miniaturized bandpass filters and a compact four-phase coupler are designed using Integrated Passive Device(IPD)technology and thin film circuit process.The main work of the thesis is as follows:1.Based on the IPD technology of Ga As substrate,the lumped capacitor and inductor are investigated,and a parameter extraction method for the lumped parameter components is analyzed.Subsequently,a modified shunt capacitor topology with a higher quality factor is proposed,which can improve the problem of rapid decrease in quality factor due to MIM(Metal Insulator Metal)capacitance achieving a large value.Finally,three miniaturized bandpass filters for wireless communication are designed using a third-order elliptic function filter circuit,with dimensions of0.6×0.65 mm~2(0.00078λ_g~2),0.42×0.58 mm~2(0.0011λ_g~2),and 0.5×0.2 mm~2(0.0093λ_g~2),respectively.2.To address the problems of the conventional Low Temperature Co-fired Ceramics(LTCC)technology,such as inadequate screen printing accuracy and low capacitance density,a low-cost filter design scheme based on multilayer dielectrics and thin film circuit process is proposed by referring to the design ideas of high density MIM capacitors in thin film IPD technology,which is used to improve the shortcomings in LTCC technology.Based on this multilayer structure and using the third-order elliptic function filter circuit,miniaturized three-layer and five-layer dielectric lumped parameter filters are designed for the Bluetooth communication band.The insertion loss of the designed filters is less than 1 d B and the dimensions are 3.3×2.4 mm~2(0.0051λ_g~2)and 1.5×1.42 mm~2(0.0013λ_g~2),respectively.3.A four-phase coupler architecture consisting of Lange couples and Marchand balun is adopted,and the principles of implementing four-phase,Lange coupler,and Marchand balun are analyzed.The miniaturized Lange coupler and Marchand balun are then realized using microstrip transmission lines and the method of bending the coupling lines,respectively.Finally,a compact four-phase coupler with the dimension of 9.5×8.2 mm~2(0.014λ_g~2)is designed using a thin film circuit process on an alumina ceramic substrate.The amplitude imbalance of the designed coupler is less than 0.9 d B and the phase error of the four ports is within±2.4~°.