Independently Controllable Dual-Band Bandpass Filters Using Asymmetric Stepped-Impedance Resonators
Independently Controllable Dual-Band Bandpass Filters Using Asymmetric Stepped-Impedance Resonators
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DOI：
10.1109/tmtt.2011.2168973
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发表时间：
2011-10
影响因子：
4.3
通讯作者：
C. Kim;K. Chang
中科院分区：
文献类型：
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作者：
C. Kim;K. Chang
本文提出了一种双频带带通滤波器，每个通带具有独立的可切换性。通过利用非对称阶跃阻抗谐振器的谐波比，设计了 2.4GHz 和 5.2GHz 谐振器。 2.4 GHz 谐振器的第二个谐振设计为通过延长馈线产生的传输零来抑制。为了实现较宽的上阻带，5.2GHz 谐振器的设计方案是这些谐振器的第二个峰值不会出现在低于 2.4GHz 谐振器的第三个峰值的频率处。使用从电磁仿真获得的信息绘制了几个用于确定几何参数和传输零点的设计图。在提取谐振器之间的耦合系数时，固定 50Ω 端口的外部品质因数以确定精确的传输零点。开发了钩式和螺旋式两种馈线，选择螺旋式馈线实现可切换过滤器。通过控制p-i-n二极管，在模拟和实验中清晰地呈现了可切换双频带的四种状态。
This paper presents a dual-band bandpass filter with independent switchability of each passband. By taking advantage of harmonic ratio of asymmetric stepped-impedance resonators, 2.4- and 5.2-GHz resonators are designed. The second resonance of 2.4-GHz resonators is designed to be suppressed by a transmission zero created by extended feed lines. To achieve a wide upper stopband, 5.2-GHz resonators are designed with a scheme that the second peak of these resonators would not appear at a frequency lower than a third peak of 2.4-GHz resonators. Several design graphs for deciding both geometric parameters and transmission zeros are plotted by using the information obtained from electromagnetic simulations. While extracting coupling coefficients between resonators, an external quality factor at 50-Ω port is fixed to determine the precise transmission zeros. Two kinds of feed lines, such as a hook type and a spiral type, are developed, and spiral-type feed lines are chosen for realizing switchable filters. By controlling p-i-n diodes, four states of switchable dual bands are clearly presented in simulations and experiments.