Acoustic-wave lumped-element resonator (AWLR)-based filters with reconfigurable all-pass-to-bandstop transfer function are reported. They are based on in-series cascaded resonant stages that comprise two parallel RF signal paths, namely: 1) a thru-line and 2) an AWLR-based resonant section. Reconfigurability is achieved by altering the phase of the thru-line through varactors. In this manner, the filter response can be reconfigured from an all-pass to an enhanced fractional bandwidth (FBW)—i.e., wider than the electromechanical coupling coefficient $k_{t}^{2}$ —bandstop one. For practical validation, two prototypes were designed and tested. They include 1) a single-stage prototype with insertion loss (IL) < 0.38 dB in the all-pass mode and a bandstop mode with a center frequency of 917.5 MHz, an FBW of 0.29% ( $2.4~k_{t}^{2}$ ), and a stopband isolation of 21.2 dB and 2) a two-stage prototype that exhibits an all-pass mode with IL < 0.67 dB and a bandstop mode centered at 916.9 MHz, with an FBW of 0.47% ( $3.8~k_{t}^{2}$ ) and a tunable isolation between 20 and 43 dB.

中文翻译：

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可重新配置的全通带阻声波集总元件谐振器滤波器

报告了具有可重构全通带阻传递函数的基于声波集总元件谐振器 (AWLR) 的滤波器。它们基于包含两个并行 RF 信号路径的串联级联谐振级，即：1) 直通线和 2) 基于 AWLR 的谐振部分。可重构性是通过变容二极管改变直通线路的相位来实现的。通过这种方式，滤波器响应可以从全通重新配置为增强的分数带宽 (FBW)，即比机电耦合系数更宽 $k_{t}^{2}$ ——带阻之一。为了实际验证，设计并测试了两个原型。它们包括 1) 在全通模式和带阻模式下插入损耗 (IL) < 0.38 dB 的单级原型，中心频率为 917.5 MHz，FBW 为 0.29% ( $2.4~k_{t}^{2}$ )，以及 21.2 dB 的阻带隔离度和 2) 两级原型，展示了 IL < 0.67 dB 的全通模式和以 916.9 MHz 为中心的带阻模式，FBW 为 0.47% ( $3.8~k_{t}^{2}$ ) 和 20 到 43 dB 之间的可调隔离。