應用於射頻前端系統之高整合度主動式帶通濾波器設計

Highly integrated active band pass filter designs for RF front end application

夏維凡(Wei-fan Hsia)

指導教授 ： 林祐生

國立中央大學/資訊電機學院/電機工程學系/碩士(2012年)

摘要

本論文研究主軸為開發一具高整合性的主動式帶通濾波器之設計方法，目標為整合單刀雙擲帶通濾波器、低雜訊放大器以及平衡至不平衡轉換器等電路方塊並藉由此整合性設計，改善傳統分時多工射頻通訊系統與各級元件串接所產生的不匹配損耗，並達到縮小面積，提高系統整合度的目的。

本論文主要提出兩種設計方法，其一為使用多重耦合線作為設計基礎實現單刀雙擲帶通濾波器，並額外加上主動式負載提供負阻達到損耗補償的效果。由於本論文所使用的負阻架構為共源極加上串聯電阻電容電感回授。不同於傳統的震盪器設計方法，此架構沒有使用共閘極回授，或是額外的源級或汲極至閘極的回授路徑，因此不會造成雜訊指數的上升。
另一則是以濾波器植入損耗法設計出發，以可匹配至複數阻抗之帶通濾波器來設計低雜訊放大器的前端匹配電路，使其具有帶通的響應，後端匹配則使用五線式多重耦合線實現具帶通響應的平衡至不平衡轉換器，在以耦合線結合單刀雙擲切換功能，如此即可將單刀雙擲、帶通濾波器、低雜訊放大器與平衡至不平衡轉換器整合置單一元件內。

針對此研究提出的設計方法，以微波基板及積體製程進行電路時做驗證可行性。透過本研究所提出之高整合度的電路架構及簡潔的設計流程，可整合多種射頻前端功能元件於同一電路中，對於射頻前端電路的微小化、於效能提升與降低設計複雜度均有直接助益。

關鍵字

主動式帶通濾波器 ； 射頻前端系統

並列摘要

This study investigates the systematic method in designing highly integrated active band-pass filters. The target is to integrate the SPDT (Single Pole Double Throw) RF switch, LNA (Low noise amplifier), balun and band-pass filter into a single circuit. By this integrated design we can improve the mismatch loss of conventional RF front end system, and schieve the goal of miniaturization and improve the level of integration in system design.

Two design approaches are proposed to achieve the above design goal. The first one is based on the integration of bandpass filter and SPDT RF switch using the multicoupled line structure, and combined the active loaded which can provide the negative resistance to compensate the insertion loss. The proposed active load is based on a common-source structure with an R–L–C series feedback, which is different from the conventional types in the oscillator design methods. It does not use a common-gate series feedback structure or any additional drain- or source-to-gate parallel feedback paths that may degrade the noise performance. Therefore, the noise figure can be improved by the proposed topology.

The second design is based on the insertion loss method for filter design to achieve the complex impedance matching of the LNA input, such that the amplifier can have a band-pass response. As for output matching of LNA we use the multicoupled line structure to achieve the single-to-balanced bandpass filter response. Then, by integrating the SPDT switch function using coupled-lines, we can integrated the SPDT switch, band-pass filter, LNA, and balun in a single circuit.

The proposed design methods are validated using hybrid and integrated microwave circuits. The proposed methods are simple and are capable of integrating multiple functional blocks in a single circuit, which is helpful in minimizing the circuit size, improving the system performance, and also reducing the complexity of design process for RF front-end designs.

並列關鍵字

RF front end system ； Active band pass filter

參考文獻

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