低溫共燒陶瓷梳形濾波器額外傳輸零點之研究及寬頻混頻器的設計

Abstract

本論文包含兩個部份，分別是利用低溫共燒陶瓷(LTCC)來實現三階梳形濾波器與寬頻混頻器兩種被動電路。 第一部份主要探討LTCC梳形濾波器的寄生交錯耦合效應產生傳輸零點的機制，我們發現梳形濾波器的交錯耦合主要是由一、三諧振腔之間的磁性耦合產生，同時輸入輸出端接入的位置也會影響傳輸零點的位置。針對上述兩種原因，分別設計了利用帶線做主耦合、改變輸入輸出端接入位置、及使用電容做主耦合三種梳形濾波器來做比較，成功的驗證寄生交錯耦合與傳輸零點的關係。 論文的第二部分是利用LTCC技術設計寬頻混頻器，採用雙平衡混頻結構分別設計了星形及環形混頻器。星形混波器是利用Mouw的混成結理論，將共平面波導(CPW)至共平面帶線(CPS)的T-型電路實現在多層結構中，而環形混頻器則是利用兩個平衡至非平衡轉換器(Marchand balun)所組成，兩種混頻器的頻寬都可達到二倍頻左右。

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.