小型化混合电磁交叉耦合带通滤波器设计

Design of Miniaturized Hybrid-Electromagnetic Cross-Coupled Bandpass Filter

  • 摘要: 面向无线通信系统对带通滤波器高选择度小型化的需求,提出了一种基于混合电磁交叉耦合拓扑结构的滤波器。该种混合电磁交叉耦合拓扑可以克服传统三阶滤波器通过交叉耦合只能产生一个传输零点的问题,在通带两边同时产生零点,从而极大提高了三阶滤波器的选择度,为小型化高选择度滤波器提供了一种设计方案。基于该拓扑结构,设计了一款基于传统微带四分之一波长谐振器的三阶滤波器,并验证了该拓扑结构产生零点的原理。为了适应不同带宽的需求,进一步减小滤波器尺寸,又设计了一种混合微带/槽线谐振器的滤波器。该结构可以实现更高的谐振器耦合强度,从而实现更宽的滤波器带宽。

     

    Abstract: To meet the requirements of wireless system on high selectivity and miniaturization, a filter topology based on hybrid-electromagnetic cross-coupling is proposed in this paper. Differing from the traditional third-order filter which can only produce one transmission zero through using cross-coupling, the proposed hybrid-electromagnetic cross-coupled topology can introduce two transmission zeros on both sides of the passband, then greatly improves the selectivity of the low-order filter. Thus, a design scheme for miniaturized high selectivity filter can be achieved. Based on this topology, a third-order filter based on microstrip quarter-wavelength resonators is designed to verify the principle of transmission zeros generated by this topology. Then, in order to obtain wider bandwidth, a hybrid microstrip/slot-line resonator filter is designed. This structure can achieve larger coupling coefficient and larger bandwidth with a miniaturized size.

     

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