In this paper, a novel tunable dual-band bandpass filter (BPF) with independently controlled passbands and constant absolute bandwidth (CABW) is proposed. The CABW passbands of designed dual-band BPF are obtained using manageable electric and magnetic mix coupling. Furthermore, the multiple transmission paths from the input port to the output port are extended for extra transmission zeros, which results in modified selectivity of the proposed dual-band BPF. The tunability and switchability of the developed filter can be implemented by introducing a single bias voltage of varactors for each band. For the tunable dual-band BPF, the simulated results show that the center frequency (CF) of the first passband varies from 2.38 to 2.68 GHz, and the CF of the second passband varies from 3.28 to 3.88 GHz, while 3-dB absolute bandwidths are 101 ± 7 MHz and 98 ± 4 MHz, respectively. Moreover, the two passbands of the filter can also be independently switched by removing the voltage imposed on the varactor CV1 and CV2. The measured results agree well with simulated results, which verify the design theory.

中文翻译：

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基于三重传输路径的恒定绝对带宽双频可调谐带通滤波器设计

本文提出了一种具有独立控制通带和恒定绝对带宽（CABW）的新型可调谐双带带通滤波器（BPF）。设计的双频带 BPF 的 CABW 通带是使用可管理的电和磁混合耦合获得的。此外，从输入端口到输出端口的多个传输路径被扩展以获得额外的传输零，这导致所提出的双频带BPF的选择性被修改。所开发的滤波器的可调谐性和可切换性可以通过为每个频带引入变容二极管的单个偏置电压来实现。对于可调谐双频BPF，仿真结果表明，第一通带的中心频率（CF）在2.38至2.68 GHz之间变化，第二通带的CF在3.28至3.88 GHz之间变化，而3-dB绝对带宽分别为 101 ± 7 MHz 和 98 ± 4 MHz。此外，滤波器的两个通带也可以通过去除施加在变容二极管C上的电压来独立切换V1和CV2。测量结果与仿真结果吻合较好，验证了设计理论。