一种双频电调带通滤波器的设计

摘要

A dual bandpass filter (BPF) with two tunable center frequencies was presented. The proposed filter was based on two-terminal shorted stepped-impedance resonators (SIRs), which was loaded varactors between two different characteristic impedances of the transmission lines. The input and output of filter were fed by 50Ω gap coupling. Because of the folded half wavelength SIR, it effectively reduces the size of the filter with miniaturization. Through odd-even mode analysis method, the center frequency of the filter can be tuned in frequency ranges from 1.97 GHz to 2.20 GHz and from 4.15 GHz to 4.30 GHz by tuning voltage of varactor. The effectiveness of the method is demonstrated by comparison between simulation and measurement results.%提出一种新型中心频率可调谐的双频带通滤波器，该滤波器利用双端短路的阶梯阻抗谐振器(stepped-impedance resonator, SIR)结构，在其中两个不同特性阻抗传输线之间同时加载变容二极管，其输入输出结构采用50Ω的缝隙耦合馈电。采用半波长SIR的折叠型结构，实现了滤波器的小型化。并通过奇偶模的分析方法，调节变容二极管上加载的电压实现中心频率分别在1.97~2.20 GHz和4.15~4.30 GHz之间可调。比较仿真与测量结果证明了该方法有效。