This paper reports on high-order balanced bandpass filters (BPFs) that are continuously tunable in terms of frequency and bandwidth and can be intrinsically switched-off. They use a hybrid integration scheme based on two different types of capacitively loaded resonators—ceramic coaxial and microstrip—that reduce the filter size, enhance its out-of-band selectivity and common-mode suppression, and allow for multiple levels of transfer function tuning. High selectivity is obtained in the differential mode due to the high number of poles and transmission zeros present. The common mode is highly suppressed through the introduction of additional transmission zeros and resistively loaded resonators. Furthermore, the use of ceramic coaxial resonators results in supplementary transmission zeros that are used to lower the out-of-band transmission in the differential mode. Multiple levels of tuning are obtained by reconfiguring only the frequency of the BPF's resonators. For experimental validation, a tunable mixed-technology microstrip prototype was manufactured and measured at S-band. It exhibited frequency tuning between 2.22 and 2.94 GHz, bandwidth tuning between 104 and 268 MHz, and an intrinsically switched-off mode with isolation >50 dB in the differential mode. For all states, the common mode was suppressed by at least 35 dB at the center frequency and within a wide range.

中文翻译：

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使用混合技术谐振器的高阶和可调谐平衡带通滤波器

本文报告了高阶平衡带通滤波器 (BPF)，它在频率和带宽方面是连续可调的，并且可以本质上关闭。他们使用基于两种不同类型的电容负载谐振器（陶瓷同轴和微带）的混合集成方案，可减小滤波器尺寸，增强其带外选择性和共模抑制，并允许多级传递函数调谐. 由于存在大量极点和传输零点，因此在差模中获得了高选择性。通过引入额外的传输零点和电阻负载谐振器，可以高度抑制共模。此外，陶瓷同轴谐振器的使用会产生补充传输零点，用于降低差模中的带外传输。通过仅重新配置 BPF 谐振器的频率来获得多级调谐。为了进行实验验证，制造了一个可调谐混合技术微带原型，并在 S 波段进行了测量。它表现出在 2.22 和 2.94 GHz 之间的频率调谐、在 104 和 268 MHz 之间的带宽调谐，以及在差模中隔离度 >50 dB 的固有关闭模式。对于所有状态，共模在中心频率和宽范围内至少被抑制了 35 dB。在 S 波段制造和测量了一个可调谐混合技术微带原型。它表现出在 2.22 和 2.94 GHz 之间的频率调谐、在 104 和 268 MHz 之间的带宽调谐，以及在差模中隔离度 >50 dB 的固有关闭模式。对于所有状态，共模在中心频率和宽范围内至少被抑制了 35 dB。在 S 波段制造和测量了一个可调谐混合技术微带原型。它表现出在 2.22 和 2.94 GHz 之间的频率调谐、在 104 和 268 MHz 之间的带宽调谐，以及在差模中隔离度 >50 dB 的固有关闭模式。对于所有状态，共模在中心频率和宽范围内至少被抑制了 35 dB。