擴展式二重濾波器及三階橫斷式濾波器

Abstract

本論文基於解析濾波器的結構及針對合成、診斷濾波器的電子參數（也就是耦合矩陣）之電腦輔助設計提出了一套快速實現濾波器的方法。這種設計過程可以避免花費大量的時間在電路的調整上。 在擴展式二重濾波器(extended doublet filter)的架構下，我們實現了二種不同需求的濾波器電路。其中一個是為了擁有高度選擇性，而另一個則是針對在通帶具有平坦的群延遲響應。群延遲已經被證明和訊號的失真有關。如同展示在論文中的數據，我們成功地消除了將會使群延遲表現變差的非預期耦合，而量測的結果更證實了讓通帶的群延遲變化小於0.5奈秒的可行性。 對於三階的橫斷式濾波器(transversal filter)，我們建立一套快速估計相關電路參數的法則。我們定義了一個新參數-特性阻抗的比例，並且發現了它在實現濾波器的重要性。這個方法只需少次數的疊代計算，此歸因於它的快速收斂特性。在數值分析及量測結果高度一致下，更驗證了這個方法的實用及有益性。 為了要配合現今通訊系統的需求，我們讓這些濾波器都設計在中心頻2.4千兆赫，以便可以容易的整合在IEEE 802.11 b/g、ISM和藍芽的系統中。

This thesis presents the fast realization of filter configurations based on analytical analysis of the proposed structures and CAD method for synthesis and diagnosis of the electrical parameters of the filter, i.e., the coupling matrix. The design procedures avoid consuming large amount of time in circuit tuning.

In the extended doublet coupling scheme, we realize two categories of filter requirements. One is for high skirt selectivity. The other is for in-band flat group delay, which has been demonstrated in association with the signal distortion. As exhibited in the thesis, we successfully eliminate the unwanted coupling that would degrade the performance of in-band group delay. The measured data validate the possibility with the variation of in-band group delay less than 0.5 ns.

As for the 3rd-order transversal filter, we establish an algorithm for quick estimation of the related electrical parameters to be determined. We define a new parameter, the impedance ratio r, and observe its importance in realization of the filter. This algorithm only involves a few of iterations due to its fast convergence. Good agreement between analytical computation and measured results indicates that such approach is practical and useful.

In order to meet the requirement in nowadays communication systems, we design these filters with center frequency at 2.4 GHz for easy integration in the environments of IEEE 802.11 b/g, ISM, and Bluetooth standards.