臺灣博碩士論文加值系統

本論文旨在探討平衡式帶通濾波器，利用兩種電路架構設計出平衡式寬頻以及超寬頻帶通濾波器。本論文的研究主題共分為三大部份。第一部份是利用均勻阻抗共振器來設計一個三階、具差模寬頻響應與通帶內共模抑制之平衡式寬頻帶通濾波器。寬頻響應主要以強耦合機制產生模態分裂並將分裂的三個模態設計在所需的通帶範圍內來達成。同時於第二個共振器上加載一開路殘段，調整差模通帶外諧振頻率的阻抗匹配，進而達到通帶外寬止帶的效果。此外，於共模時利用對稱面特性切換錯開共振器頻率，以造成共模訊號的多級衰減，藉此抑制共模訊號。
在第二部份的研究中，研擬以微帶線饋入雙環型槽線共振器機制來設計平衡式超寬頻濾波器。其主要概念為將饋入點至槽線及微帶線尾端之距離設計為四分之一波長以形成強耦合，同時於差模操作時將槽線共振器之前三個共振模態設計於差模通帶內以形成超寬頻響應。在共模操作時，除了將兩環型槽線共振器內側線段彎斜以降低耦合量外，也同時於上層微帶線上嵌入兩個不同尺寸之陷波用共振器，來產生兩個零點以抑制共模雜訊。
本論文第三部分之平衡式超寬頻濾波器，在饋入部分改以微帶線跨越對稱面饋入槽線共振器，此饋入方式使得整個槽線共振器可沿著對稱面做佈局。操作於差模時，對稱面等效成電牆，對上層微帶線而言其終端短路，此與終端開路的四分之一波長微帶線情況相似，與下層槽線共振器仍有良好的耦合效果；對下層槽線共振器而言，因對稱面為電牆之故，其仍保有一般槽線之結構及特性，可藉由槽線共振器前三個共振模態設計於差模通帶內形成超寬頻響應。操作於共模時，對稱面等效成磁牆，其開路之等效將使槽線共振器結構遭受破壞而成為一不完整之共振器，致沿對稱面之槽線內將無磁流。由於共模模態無法形成，故可有效地抑制共模訊號。
本研究所設計之平衡式寬頻和超寬頻帶通濾波器，除模擬其特性外，亦以實作來驗證其效能，而結果顯示兩者相當吻合。預期本研究之成果可實際運用在MB-OFDM與UWB系統中，而所提出之設計方法可作為此方面相關研究之有用參考。

The objective of this thesis is to study and design balanced wideband and ultra-wideband (UWB) bandpass filters (BPFs). The proposed BPFs were designed using microstrip, slotline, or hybrid microstrip-slotline configurations. The research work is divided into three parts. In the first part, uniform-impedance resonators (UIRs) were used to design a third-order balanced BPF which has differential-mode (DM) wideband response and good common-mode (CM) rejection in the desired passband. The DM wideband response is achieved by locating evenly the three split modes (which result from strong coupling) of the resonators in the desired DM passband. Out-of-band spurious modes in the higher frequency region are suppressed by degrading impedance matching which is obtained by tuning the length of the open stub loaded on the second resonator. In CM operation, the signal is attenuated by separating resonant frequencies of the intermediate-stage resonators to obtain good CM suppression.
In the second part of this thesis, a microstrip-fed dual-ring-type slotline resonator is proposed to construct a balanced UWB BPF. Strong signal coupling is achieved by using microstrip-to-slotline transition (MST) structure for which the feeding point is located one quarter-wavelength away from the short-circuited end of the slotline and the same distant away from the open-end of the microstrip line. To obtain DM UWB response, besides using the MST feeding structure, we locate the first three resonant modes of the slotline resonator (SLR) in the passband to make it uniform and wide enough. On the other hand, to suppress CM signals, the inner, coupled sides of the two ring SLRs are made inclined to reduce the degree of coupling, and meanwhile, we implement two wave-trapping resonators of different lengths around the feeding lines to produce two transmission zeros and hence to further filter out the unwanted CM signals.
In the final part of this thesis, a UWB BPF was designed using a straight SLR which is deployed symmetrically with the plane of symmetry (POS). Again, to achieve UWB response, the first three resonant modes of the SLR are located in the in the DM passband. In addition, to obtain better signal transmission, the SLR is fed at the position which is one quarter-wavelength away from its end by microstrip lines that are placed across the POS. Thus when excited differentially, the microstrip feeding lines are equivalently short-circuited along the POS, rendering a large current distribution and large surrounding electromagnetic field around that short-circuited end. Similar to the case addressed in the second part, this will result in strong coupling between the microstrip feeding lines and the SLR. As the UWB BPF is in CM operation, the POS is virtually open, the half SLR structure is thus incomplete and no magnetic current will flow in it. Such an incomplete SLR can prevent signals transmission from the input port to the output port through the SLR, thus gives a very effective CM suppression.　
The designed balanced wide band and UWB BPFs are simulated for characteristics study and verified by measurement. Results show that the designed balance wideband and UWB BPFs are feasible for application in MB-OFDM and UWB systems. The proposed design technique could serve as a useful reference for researchers and engineers working in this and related areas.

目 錄
頁次
中文摘要 i
Abstract iii
謝誌 v
目 錄 vii
圖目錄 ix
表目錄 xi

第一章 緒論 1
1-1 研究動機 1
1-2 文獻探討 2
1-3 論文大綱 3
第二章 以均勻阻抗共振器(UIR)設計之三階平衡式寬頻帶通濾波器 5
2-1 UIR型平衡式寬頻帶通濾波器設計 5
2-2 UIR型平衡式寬頻帶通濾波器模擬與量測結果 7
第三章 應用於UWB之雙環形SLR平衡式帶通濾波器設計 14
3-1微帶線至槽線饋入機制(microstrip-slotline transition) 14
3-2 以雙環形SLR為主架構之平衡式超寬頻帶通濾波器設計 15
3-3以雙環形SLR為主架構之平衡式超寬頻帶通濾波器模擬與量測結果 16
第四章 具超廣頻域共模抑制之平衡式UWB BPF設計 24
4-1跨越對稱面之饋入線設計 24
4-2具超廣頻域共模抑制之平衡式UWB BPF設計 25
4-3具超廣頻域共模抑制之平衡式UWB BPF模擬與量測結果 26
第五章 結論 36
參考文獻 38
作者簡歷 41
圖目錄
頁次
圖2-1 UIR型平衡式寬頻帶通濾波器架構 8
圖2-2 操作於差模及共模時之等效半電路 8
圖2-3 差模操作時之共振器頻率分佈圖 9
圖2-4 圖2-2電路於差模操作時之(a) S11及(b) S21頻率響應圖 9
圖2-5 共模操作時之共振器頻率分佈圖 10
圖2-6 圖2-2電路於共模操作時之(a) S11及(b) S21頻率響應圖 10
圖2-7 以加載殘段調整差模響應之漸變圖 11
圖2-8 以殘段調整阻抗匹配之漸變圖 11
圖2-9 UIR型平衡式寬頻帶通濾波器模擬所得之(a)差模與(b)共模響應圖 12
圖2-10 平衡式寬頻帶通濾波器之實作電路圖 13
圖3-1 Microstrip-slotline transition 結構示意圖 17
圖3-2 槽線共振器前三個模態之垂直磁場分佈圖 17
圖3-3 微帶饋入線與槽線共振器之磁場耦合圖 18
圖3-4 本章所提出之平衡式超寬頻帶通濾波器架構：(a)正面和(b)反面圖 18
圖3-5 設計SLR前三個共振模態於差模通帶內之模態分布圖 19
圖3-6 操作於差模與共模時之SLR模態分布圖 19
圖3-7 操作於(a)共模與(b)差模時，WTR之等效半電路 20
圖3-8 加或未加WTR時SLR之共模響應比較圖 21
圖3-9 平衡式超寬頻BPF之量測和模擬結果：(a)差模及(b)共模頻率響應圖 22
圖3-10 平衡式超寬頻BPF之實作電路圖 23
圖4-1 跨越對稱面之槽線結構：(a) 跨於對稱面之SLR結構 (b)差模時之半電路及(c)共模時之半電路等效圖 27
圖4-2 本章所提出之具超廣頻域共模抑制之平衡式UWB BPF架構(a)正面及(b)背面圖 28
圖4-3 槽線共振器前四個模態之磁場(電流)場型分布圖 29
圖4-4 UWB平衡式電路雛型之差模與共模響應圖 29
圖4-5 終端為扇形之槽線共振器與線型槽線共振器之頻率響應比較圖 30
圖4-6 帶止濾波器架構圖：(a)單邊馬刺線，(b)雙邊馬刺線，(c)本章提出之BSF架構 31
圖4-7 帶止響應比較圖 32
圖4-8 調整L長度改善高頻響應漸變圖 32
圖4-9 加與不加BSF頻率響應之比較圖 33
圖4-10 平衡式超寬頻BPF之量測和模擬結果：(a)差模及(b)共模頻率響應圖 34
圖4-11 平衡式超寬頻BPF之實作電路圖 35

表目錄
頁次
表1-1 UWB系統規格 4
表1-2 OFDM Group A系統規格 4

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