串聯開關式濾波器庫

Abstract

本論文提出串聯開關式濾波器庫之電路結構，其目的為改進傳統並聯開關式濾波器庫當濾波通道增加時單刀多擲開關製作之困難。首先利用J-K inverter 等效耦合傳輸線設計柴比雪夫三階短路端梳形髮夾濾波器，再將PIN 二極體嵌入濾波器頭尾的共振腔，藉由二極體之順、逆偏壓控制濾波器的開關，完成單頻電子式開關濾波器的設計。接著將三個單頻電子式開關濾波器利用微帶線串接的方式，完成三通道濾波器庫的設計，本論文設計的頻帶分別在Band40、WIFI band 以及Band38。實作電路使用Rogers RO4003，厚度20 mil，介電常數 3.55、損耗正切0.0027 的板材實現，使用Agilent E8364B PNA Network Analyzer 進行電路的量測。

The thesis studies a series-switching filter bank structure that solves the difficulty of fabrication of SPNT switch of the conventional parallel-switching filter bank as the channel number becomes large. At first, use J/K inverters equivalent coupled transmission lines to design a third-order Chebyshev short-ended hairpin comb filter. Next, to insert a PIN diode at the center of first and last resonators finishes the single electronically switchable filter design which can be switched on and off by reverse and forward biasing the PIN diodes. Finally, serially connecting three of the electronically switchable filters by transmission lines with appropriate lengths accomplishes the proposed three channel filter bank. The center frequencies of filter bank are 2.35 GHz, 2.425 GHz and 2.55 GHz that correspond to Band40, WIFI band and Band38 respectively. The circuit are fabricated using Rogers RO4003 substrate with thickness of 20 mil, dielectric constant of 3.55 and dielectric loss tangent of 0.0027, and measured by Agilent E8364B PNA Network Analyze.