Study Extra Transmission Zero of LTCC Combline Filters and Development of LTCC Broadband Mixers

• Main Authors: Tsung-Hsien Lin, 林宗賢
• Other Authors: Chi-Yang Chang
• Format: Others
• Language: en_US
• Published: 2003
• Online Access: http://ndltd.ncl.edu.tw/handle/29606722764271708797

碩士 === 國立交通大學 === 電信工程系 === 91 === Two passive circuits, three-pole comb line bandpass filters and broadband mixers, which are realized using low temperature co-fired ceramics (LTCC) are described in this thesis. PartⅠ studies the effect of transmission zeros produced by parasitic cross coupling of LTCC comb line filters. We have proved that magnetic coupling between first and third resonators dominates the extra transmission zero. The input and output tap position can also affect the position of transmission zeros. Due to these two reasons, we design three types of comb line filters to compare the performance. The three types of filters are strip-line coupled combline filter, combline filter with different input/output tap position, and capacitor coupled combline filter respectively. The measured results confirm that the transmission zeros generated by parasitic cross coupling match well with our analysis. Part Ⅱ describes the development of broadband mixers using LTCC technology. We utilize doubly balanced configurations to design a star mixer and a ring mixer. The star mixer is modified from Mouw’s hybrid junction theory and is realized by coplanar waveguide (CPW) to coplanar strips (CPS) T-junctions in multilayer structure. The ring mixer comprises two balanced to unbalanced transformers (Marchand balun). Both kinds of the mixers show a bandwidth of an octave.