Tunable 1.25–2.1-GHz 4-Pole Bandpass Filter With Intrinsic Transmission Zero Tuning
Tunable 1.25–2.1-GHz 4-Pole Bandpass Filter With Intrinsic Transmission Zero Tuning
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DOI：
10.1109/tmtt.2015.2409061
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发表时间：
2015-03
影响因子：
4.3
通讯作者：
Tao Yang;Gabriel M. Rebeiz
中科院分区：
文献类型：
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作者：
Tao Yang;Gabriel M. Rebeiz
提出了一种四极点可调谐带通滤波器传输零点调谐的新概念。在这项工作中，传统上用于带宽控制的调谐元件也被用于同时调整TZs。结果，可以在不增加滤波器阶数和复杂度的情况下控制可调谐滤波器的选择性。一个4极点带状线滤波器被用来证明这一概念。该滤波器可在1.25 ~ 2.1GHz范围内连续调谐，并采用两个TZs使阻带抑制在200 MHz处达到> 60 dB。这些TZs也可以从上阻带移动到下阻带，而无需任何辅助调谐元件来显著改变阻带抑制。高抑制滤波器在具有大干扰的无线系统和认知无线电中是有用的。
A new concept of tuning transmission zeros (TZs) in 4-pole tunable bandpass filters is demonstrated. In this work, the tuning elements that were conventionally used for bandwidth control are also utilized for adjusting the TZs at the same time. As a result, the selectivity of the tunable filter can be controlled without increasing the filter order and complexity. A 4-pole stripline filter is used to demonstrate this concept. The filter can be continuously tuned from 1.25 to 2.1 GHz and two TZs are employed to improve the stopband suppression to > 60 dB at 200 MHz from the passband. These TZs can also be moved from the upper stopband to the lower stopband without any auxiliary tuning elements to significantly change the stopband suppression. The high rejection filter is useful in wireless systems and cognitive radios with large interferers.