本論文研究主軸為具高整合性射頻前端收發系統設計。首先提出新式單刀雙擲帶通濾波器架構，藉由帶通濾波器與單刀雙擲切換器的整合式設計，進而改善傳統分時多工射頻通訊系統必備之切換器與濾波器於串接時，各級間不匹配之損耗，並達到縮小電路尺寸之目的。本研究係以耦合微帶線帶通濾波器出發，引入二極體負載達到切換功能，透過首段耦合線長度的控制，再直接利用T 接面將兩濾波器並接，即可得到具單刀雙擲功能之帶通濾波器。本架構設計關鍵在首段耦合線長度，後端電路實現方式可任意選用，提供設計者高自由度，例如可進一步將單刀雙擲帶通濾波器結合平衡至不平衡轉換器，大幅提高整合度。再者，運用濾波器可匹配至複數阻抗之特性，將低雜訊放大器輸入級匹配電路設計為具切換功能之帶通濾波器，而可將單刀雙擲切換器、帶通濾波器、低雜訊放大器三者整合於單一電路元件中，對於射頻前端電路的微小化，效能提昇，與組裝複雜度降低均有直接助益。 本研究透過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方塊於同一電路中，目前已達成整合部份射頻前端主被動電路之設計目標，同時也為未來進一步的改良提供更多可能性。In this study, highly integrated RF frontend designs are presented. First, the novel bandpass single-pole-double-throw (SPDT) RF switch design that combines the functions of bandpass filter (BPF) and SPDT is proposed. As a result, both the circuit size and mismatch losses associated with the cascade of these two components in the RF frontend of conventional time-division-duplex system can be reduced. The proposed SPDT BPF design starts from a microstrip parallel-coupled BPF loaded with a p-i-n diode at the end of first coupled-line. In this way, the BPF becomes switchable. By properly chosen the length of first coupled-line, two switchable BPFs can be directly connected to form a SPDT BPF. In addition, since only the first coupled-line is determined by the switch function, the subsequent filter stages can be arbitrarily designed such them more functions can be integrated and more design freedom is obtained. For instance, the integration of balun function to the bandpass SPDT switch is demonstrated, such that the level of integration is further improved. Moreover, the design technique of BPF with complex load is applied to the matching network design of a Low Noise Amplifier (LNA). In this way, a SPDT switch, two BPF’s, and a LNA are all integrated in a single circuit. It will help reducing the circuit size, mismatch losses, and complexity in module for RF frontend design. The proposed SPDT BPF features compact circuit structure and simple design flow, and is capable of further integration of other circuit components. The integration of several active and passive function blocks in the RF frontend has been achieved. The proposed circuit structure and design method also paves the way for further improvement in the near future.
