論文摘要 本論文利用GaAs 積體電路來實現單晶片帶通濾波器，提出兩種非常適合實 現於GaAs 單晶片系統的濾波器架構。首先，本論文提出「新式步階阻抗微帶耦 合線帶通濾波器」來設計Q-Band 毫米波寬頻帶通濾波器，通帶範圍為 31.3~45GHz，在此架構中，利用步階阻抗概念實現共振器長度小於四分之一波長 的微帶耦合線帶通濾波器，其電路面積較傳統使用四分之一波長共振器設計者縮 小1/4 以上，並且利用傳輸零點使29GHz 的衰減量大於37dB，可應用於ALMA Band-1 無線電波天文望遠鏡接收機系統，並大幅減少接收機體積與整合難度。 此外，本論文亦提出「新式電容負載髮夾型微帶耦合線帶通濾波器」來設計 K-Band FMCW 雷達系統用窄頻帶通濾波器，通帶範圍為24~26GHz，在此架構中， 利用新式電容負載髮夾型共振器為基礎所設計的帶通濾波器，其電路面積較傳統 使用二分之一波長共振器設計者縮小3/4 以上，且30dB 止帶衰減的頻率上限可 大於0 2.68fo 。而本論文也另設計一Q-Band 波導管帶通濾波器，做為單晶片帶通 濾波器的特性比較參考標準。 針對本論文提出的兩種帶通濾波器架構，我們皆先以印刷電路板設計射頻頻 段帶通濾波器來驗證所提出的設計流程與公式，並都達到良好的特性，第一種設 計透過步階阻抗共振器的特性可以將止帶頻寬拓展到7.6fo ；第二種設計透過電 容值的選擇，可以將每段耦合線長度縮小到 λ/12 以下，實做與模擬結果也都很 吻合。 在本論文中，針對各式微帶耦合線的不同特性均詳細加以研究，並討論應用 於濾波器的最佳實施方式，而針對各種設計，均有一整套簡捷明瞭的設計流程作 為設計工具，同時也為未來進一步的改良提供更多的設計彈性。 Abstract In this study, two kinds of on-chip bandpass filters are proposed and implemented using the GaAs pHEMT process. They are very suitable for the design of GaAs single-chip transceiver. For the Q-Band bandpass filter with wide bandwidth from 31.3 to 45GHz, the novel planar coupled-line filters with step-impedance resonators are proposed. The resonators can be made much smaller than conventional quarter-wavelength resonators. Compared to the conventional parallel-coupled bandpass filters that are based on quarter-wavelength resonators, the circuit size of proposed filters are reduced by more than 1/4. In addition, by utilizing the inherent transmission zeros resulted from cross-coupling, the rejection at 29GHz is better than 37 dB . The proposed Q-Band filters meet the requirements of ALMA Band-1 radio telescope receiver, and have the advantages of reducing size, weight, and complexity in system integration. On the other hand, for the K-Band bandpass filter with narrow bandwidth from 24 to 26GHz, the planar hairpin-line filters with loaded capacitors are proposed. The circuit size of this filter can be reduced by half compared to conventional hairpin-line bandpass filters. The 30dB stopband bandwidth of proposed K-Band filter can be extended up to 4.6fo . In addition, a WR22 waveguide-based Q-Band bandpass filter is also implemented for bench-marking. In order to verify the effectiveness of proposed filter design equations and procedure, two planer bandpass filters with bandwidths from 2.3~2.7GHz are also fabricate on PCB. For the step-impedance design, the 30 dB stopband bandwidth is up to 7.6fo . For the hairpin filter with loaded capacitor, the length of coupled-line can be reduced to λ/12 . All the measurement results agree well with the simulation ones. In this work, the characteristics of different kinds of coupled-line sections are thoroughly investigated so as to make the best use of them in bandpass filter designs. Simple and explicit design flows have also been proposed for all designs, which allow the easy extension of proposed filter structures for further improvement in the future.
