過模共振腔波導濾波器之微小化設計及製程誤差之抑制

Manufacturing Error Effect Suppression of Laminated Waveguide Filters Using Overmoded Cavities with Miniaturized Design

郭明軒(Ming-Hsuan Kuo)

指導教授 ： 吳瑞北

國立臺灣大學/電機資訊學院/電信工程學研究所/碩士(2015年)

https://doi.org/10.6342/NTU.2015.01557

摘要

本論文探討疊層波導過模共振腔的特性及其應用。首先使用低溫共燒陶瓷(LTCC)技術分別實作毫米波頻段之過模與基模濾波器，模擬製程誤差對其效能造成的影響，分析其結果並以實驗驗證，進而提出以折疊過模共振腔實作之雙模濾波器，完成微小化設計。
欲分析製程誤差對濾波器效能造成的影響，本論文使用三組以不同模態實作但相同規格的濾波器，分別加入各項製程誤差參數並分析，包含層間錯動、金屬印製與金屬厚度誤差。分析結果顯示，使用過模共振腔的濾波器，在各項誤差中都有較好的抑制表現，其中以層間錯動誤差抑制效果尤佳，此誤差造成基模濾波器在中心頻率之反射損耗僅能維持在5dB而過模濾波器仍能保有15dB以上。
本論文同時提出過模共振腔在毫米波頻段的進階應用，以雙折過模共振腔之雙模濾波器架構為基礎，藉由改變共振腔四周邊界條件，調整不同模態的共振頻率比，同時堆疊共振腔時適當選取槽線位置，獨立控制不同模態下的耦合係數與外部品質因子，完成微小型過模共振腔濾波器設計。此法使用了鄰近模態為其共振模態，因此通帶外輸入損耗可降至25dB以上，且在電路面積的微小化上，相較於傳統未折疊四階濾波器，體積可縮小至原始大小的72.7%與54%。

關鍵字

疊層波導 ； 低溫共燒陶瓷 ； 多模態 ； 濾波器 ； 製程誤差 ； 雙折共振腔

並列摘要

The characteristics and applications of overmoded laminated waveguide cavities are investigated in this thesis. Laminated waveguide filters using either fundamental mode or overmoded cavities are firstly designed at millimeter frequencies in low temperature co-fired ceramic (LTCC) substrates. The performance variations of different filter designs due to manufacturing error are then examined by simulation. Finally, folded overmoded cavities are proposed to accomplish a miniaturized design of a dual-mode 4th order filter.
In order to analyze the performance variation due to manufacturing error, two different filter groups with the same specification but different cavity modes are designed in this thesis. The performance of these filters are then examined with respect to different kinds of manufacturing error, inclusive of layer to layer alignment error, metal printing error, and metal thickness error. The analysis showed that the performance variation due to manufacturing error can be more effectively suppressed for filter designs using overmoded cavities, compared to those using fundamental mode cavities. Especially for the layer to layer alignment error, filters using TE101 suffer great distortion with return loss at center frequency is 5dB while TE301 remains above 15dB.
Advanced applications of overmoded cavities at millimeter-wave frequency bands are also proposed in this thesis. A miniaturized design is accomplished by double- folded overmoded cavities in dual-mode filter configuration. By changing the boundary condition of double-folded overmoded cavities to adjust the ratio of resonant frequencies, vertically stacking the proposed novel cavities with proper slot positions to realize the external quality factors and coupling coefficients with respect to different modes, a miniaturized overmoded cavity filter can be accomplished. Due to the absence of neighboring modes, the proposed filter has excellent out-band performance with insertion loss less than 30dB and the circuit size reduced to 72.7% of double folded filter using fundamental mode and 54% of original 4th order filter with unfolded cavities.

並列關鍵字

laminated waveguide ； low-temperature co-fired ceramic ； multi-mode ； filter ； manufacturing error ； double-folded cavity

參考文獻

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