Analysis and Design of Multilayer RF Bandpass Filter

• Main Authors: Sun Shih-Chih, 孫世志
• Other Authors: Yu Cheng-Cheh
• Format: Others
• Language: zh-TW
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/70250954124877910942

碩士 === 國立臺北科技大學 === 電腦通訊與控制研究所 === 92 === As wireless communication technologies are popularized all over the world, compact multilayer RF components and devices have become a crucial design issue for research and development, such as chip capacitor, inductor, filter, balun, diplexer, antenna, and so forth. Nowadays, multiplayer passive components or devices realized on low temperature co-fired ceramic (LTCC) have become one of the major technological streams for circuit miniaturization. In view of the importance of circuit miniaturization using multiplayer technology, this thesis aims at the design and implementation of RF lumped bandpass filters using multilayer structures. With the prototype circuit of a particular lumped bandpass filter specified, an adequate multiplayer distributed metalization pattern is then laid out and the equivalent lumped component value of every individual distributed element is extracted with the aid of a full-wave electromagnetic simulator and the well-known s-parameters. To embark on the design of a multilayer lumped bandpass filter, the building blocks associated are first developed, including distributed layout, broadband analysis, narrowband parameter extraction, fabrication, and measurement of single stand-alone grounded capacitor, series capacitor, grounded inductor, series inductor, and two-winding transformer as well. Owing to the electromagnetic field interaction among various distributed metalized elements within the multilayer structure, either capacitive or inductive or combination of the two, precise equivalent lumped parameter extraction and efficient iterative modification is worthy of special awareness during the design process. Based on the preceding L/C building blocks, two RF elliptic-function lumped bandpass filters designed with multilayer structures and Dupont LTCC parameters are designed, simulated, optimized, and laid out, one for 2.45 GHz ISM (Industrial, Scientific, Medical) band application and the other for 5.41 GHz UNII (Unlicensed National Information Infrastructure) band. The simulated characteristics of the 2.45 and 5.41 GHz bandpass filters designed, including the passband insertion loss, bandwidth, shape factor, and stopband transmission zeros are found very much comparable to those designed and manufactured by Johanson Technology, Inc. using the LTCC technology。 In order to verify that the design capability utilizing multilayer structures has been well established in this study, another five bandpass filters are designed, simulated, optimized, laid out, and fabricated with both 1.45 mm- and 0.4 mm-thick FR4 PCB’s (printed circuit boards), two for 868 ~ 870 MHz European ISM band application, and three for 902 ~ 928 MHz US ISM band. With accurate in-fixture calibration for both the vector network analyzer and the microstrip test fixture adopted, measured results are found to exhibit good agreement with all the simulated scattering parameters.