Design of Fourth-Order Frequency Tunable Bandpass Filter Using Varactor-Loaded Step-Impedance Resonators

被引：0
|
作者：
Li S. [1 ]
Li S. [1 ]
Liu J. [1 ]
Zhang N. [1 ]
Shi M. [1 ]
机构：
[1] Xi’an Institute of Space Radio Technology, Xi’an
来源：
Dianzi Keji Daxue Xuebao/Journal of the University of Electronic Science and Technology of China | 2024年 / 53卷 / 03期
关键词：
bandpass filter; microstip; tunable filter; varactor-loaded step impedance resonator;
D O I：
10.12178/1001-0548.2023202
中图分类号：
学科分类号：
摘要：
In this article, a compact fourth-order frequency tunable Bandpass Filter (BPF) with four Transmission Zeros (TZs) based on Varactor-Loaded Step-Impedance Resonators (VL-SIRs) is presented. With the utilization of VL-SIRs, the Tuning Range (TR) of the proposed fourth-order BPF is improved. Besides, by introducing cross coupling between VL-SIRs, a pair of TZs close to the passband are produced and the selectivity of the filter is enhanced significantly. Another pair of TZs are generated to improve the out-of-band rejection by using source-load coupling. Moreover, the Frequency-Dependent Coupling (FDC) structures based on VL-SIRs are employed to realize constant Absolute Bandwidth (ABW). The simulated and measured results are presented and show good agreement. The measured results exhibit a tuning range from 0.78 GHz to 1.15 GHz with a 3 dB constant ABW of about 55±3 MHz, the return loss of the filter is greater than 10 dB and the insertion loss is about 2.8 dB to 3.3 dB. © 2024 University of Electronic Science and Technology of China. All rights reserved.
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页码：359 / 365
页数：6
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