Miniaturized tri-band balanced filter based on a novel asymmetric stepped impedance resonator with self-coupling
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摘要: 针对平衡滤波器的高集成度和高选择性的应用需求,基于一种新型自耦合非对称阶梯阻抗谐振器提出了一种具有高选择性的小型化三通带平衡滤波器。首先通过该平衡滤波器的差模和共模等效电路详细分析了其谐振器结构的谐振特性,并利用差模等效电路下的前三个谐振模式来分别实现三个通带。另外通过在电路对称面上加载电容和电阻元件来提高对共模噪声的抑制,且不影响差模频率响应特性。基于提出的多模平衡滤波器结构和设计方法,设计了一个通带频率为2.75/4.46/6.21 GHz的三通带平衡滤波器,并对其进行了加工和测试,结果表明,该结构可以实现紧凑的体积和高选择特性,并且具有很好的共模抑制特性。
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关键词:
- 平衡滤波器 /
- 三通带 /
- 共模抑制 /
- 自耦合 /
- 非对称阶梯阻抗谐振器
Abstract: For the application requirements of high integration and high selectivity of balanced filters, this paper proposes a novel balanced tri-band filter with high selectivity, which is based on an improved asymmetric stepped impedance resonator structure with self-coupling. Firstly, through the differential mode and common mode equivalent circuits of the balanced filter, the resonant characteristics of the resonator structure are specifically analyzed, and the first three resonance modes under the differential mode equivalent circuit are used to form three passbands respectively. In addition, by loading capacitors and resistance elements on the symmetrical surface of the circuit, the suppression of CM signals can be improved without affecting DM signals based on the proposed multimode balanced filter structure and design method, and a balanced tri-band filter with passband frequencies of 2.75/4.46/6.21 GHz was designed, processed and tested. The results show that the structure can achieve a compact size and high selection characteristics, and has good common mode rejection characteristics. -
表 1 与已发表的多通带平衡滤波器结果对比
Table 1. Comparisons with the previous multi-band balanced BPFs
source f0DM/GHz 3-dB FBW/% |S21| @ CM>20 dB/(GHz) insertion loss/dB TZs circuit size/λg×λg ref. [3] 2.5/5.9 14.0/6.6 1.0−8.0 3.21/3.9 2 0.48×0.28 ref. [4] 1.64/2.54 4.4/2.96 0.5−3.5 2.266/2.97 5 0.73×0.52 ref. [6] 2.5/3.5/5.8 13.2/3.1/3.5 2.0−8.0 0.8/2.3/2.4 1 0.38×0.2 ref. [8] 2.4/3.51/5.2 7.0/5.5/3 1.0−7.0 2.43/3.5/3.6 6 0.49×0.35 ref. [11] 2.45/3.5/5.25 1.22/2/1.52 2.0−8.0 0.71/0.92/0.67 5 0.56×0.43 this work 2.75/4.45/6.21 9.1/7.6/5.0 1.0−8.0 0.94/1.82/2.02 3 0.45×0.27 -
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