應用於現代無線通訊系統之低溫共燒陶瓷雙工器設計

雙工器是現代無線通訊系統中的關鍵元件，其主要功能為將不同頻率成分的訊號分流至不同路徑。雙工器可使發射機與接收機共用一支天線，因此可省下額外的天線成本。雙工器有許多設計方法，其中一個方法為使用T型接面或雙模態共振器做為匹配電路結合兩個帶通濾波器。然而，由於此匹配電路與導波結構中的電氣長度有關，因此往往不利於縮小化設計。另一個方法是使用人造傳輸線產生不同訊號路徑，雖然整體電路面積可大幅縮小，但對隔離度的要求通常需有所取捨。因此，本篇論文將交叉耦合帶通濾波器與微型化匹配電路結合，提出一集總式雙工器電路，可同時達到高隔離度及小尺寸的設計目標。於簡介完交叉耦合帶通濾波器的理論基礎後，本篇論文先提出一個方法補償導抗轉換器的非理想特性。藉由引入更多設計自由度，通帶內的不匹配以及頻率偏移可有效補償，利於設計集總式帶通濾波器。當兩個所需的帶通濾波器設計完畢，便可依據本篇論文理論加入一集總式匹配電路，完成雙工器設計。本篇論文提出的雙工器可達至50 dB的隔離度，且電路大小只有0.072λg × 0.038λg，與文獻中的雙工器相比，本論文所提出的電路具有高隔離度並能達到較小的電路尺寸。此外，本論文也提出一個用於兩個緊鄰頻帶的雙工器電路，隔離度可藉由電路中同時存在的高阻抗及低阻抗路徑有所提升，而使用高選擇性帶通濾波器可減低雙工器在GPS以及Bluetooth 頻帶所受的干擾。本論文提出的架構可達至38 dB的隔離度，並在GPS及Bluetooth頻帶提供至少30 dB的雜訊抑制。

關鍵字

雙工器；匹配電路；隔離度；集總式架構；微型化

並列摘要

Duplexers are key components in modern wireless communication systems. The main function is dividing signals of different frequencies into different paths. By using duplexers, antennas can be shared by both transmitters and receivers and thus the number of antennas can be reduced. The duplexer can be realized by different methods. One way is combining two bandpass filters with conventional matching network, usually T-junction or dual-mode resonator is used. However, because the size of matching network is closely related to the electrical length in the material, the capability of miniaturization is limited. Another way is using artificial transmission lines to generate different signal paths. Though the circuit size can be significantly reduced, the isolation level is usually a trade-off. Therefore, this thesis proposes a lumped element duplexer schematic which is the combination of cross-coupled bandpass filters and miniaturized matching network. Both high isolation level and small circuit size can be achieved. After introducing the basic theory of the cross-coupled bandpass filter, a compensation method for non-ideal immittance inverter is proposed in this thesis. The mismatch in passband and frequency shifting can be compensated effectively by introducing more design degree of freedom, thus the lumped bandpass filter topology can be obtained. When two bandpass filters are finished, a lumped matching network can be applied to form a duplexer based on the theory in this thesis. The proposed duplexer achieves 50 dB isolation level with circuit size 0.072λg × 0.038λg. The proposed circuit has higher isolation level and can reach smaller size compared with several previous works. Besides, a duplexer schematic for two close bands is also proposed. By introducing both high-impedance path and low-impedance path, the isolation level can be improved. The proposed duplexer achieves 38 dB isolation level. Also, 30 dB suppression at GPS/Bluetooth bands is achieved by using the selective bandpass filter.

並列關鍵字

duplexer ； matching network ； isolation ； lumped topology ； miniaturization

參考文獻

[1] 3GPP website : http://www.3gpp.org/.

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[4] F. Cheng, X.-Q. Lin, Z.-B. Zhu, L.-Y. Wang and Y. Fan, “High isolation diplexer using quarter-wavelength resonator filter,” Electron. Lett., vol. 48, pp. 330–331, Mar. 2012.

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[5] E. E. Djoumessi, “Compact packaged Diplexer Based on Highly Selective Dual-Mode Bandpass Filter,” in IEEE Microwave Magazine., vol. 12, pp. 89–93, Feb. 2011.

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應用於現代無線通訊系統之低溫共燒陶瓷雙工器設計

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