Abstract In this paper, a tunable balanced-to-balanced in-phase filtering power divider (FPD) is designed, which can realize a two-way equal power division with high selectivity and isolation. A differential-mode (DM) passband with a steep filtering performance is realized by applying microstrip stub-loaded resonators (SLRs). Meanwhile, six varactors are loaded to the SLRs to achieve the center frequency (CF) and bandwidth adjustment, respectively. U-type microstrip lines integrated with stepped impedance slotline resonators are utilized as the differential feedlines, which suppress the common-mode (CM) intrinsically, making the DM responses independent of the CM ones. A tuning center frequency from 3.2 to 3.75 GHz and a fractional bandwidth (12.1–17.6%) with more than 10 dB return loss and less than 2.3 dB insertion loss can be achieved by changing the voltage across the varactors. A good agreement between the simulated and measured results is observed. To the best of authors' knowledge, the proposed balanced-to-balanced tunable FPD is first ever reported.

中文翻译：

---

具有高共模抑制的可调平衡到平衡滤波功率分配器

摘要 本文设计了一种可调平衡到平衡同相滤波功率分配器（FPD），可实现高选择性和高隔离度的双向等功率分配。具有陡峭滤波性能的差模 (DM) 通带是通过应用微带短线加载谐振器 (SLR) 实现的。同时，六个变容二极管加载到 SLR，分别实现中心频率 (CF) 和带宽调整。U型微带线与阶梯阻抗槽线谐振器集成在一起用作差分馈线，其本质上抑制了共模（CM），使DM响应独立于CM响应。调谐中心频率为 3.2 至 3.75 GHz，部分带宽 (12.1–17.6%) 具有超过 10 dB 的回波损耗且小于 2。通过改变变容二极管两端的电压可以实现 3 dB 的插入损耗。观察到模拟结果和测量结果之间的良好一致性。据作者所知，提议的平衡到平衡可调 FPD 是首次报道。