基于双面平行带线的绝对带宽不变频率可调带通滤波器

Tunable Bandpass Filter with Constant Absolute Bandwidth Using Double-Sided Parallel-Strip Lines

摘要: 提出基于双面平行带线结构的电容加载绝对带宽不变频率可调平面带通滤波器，通过选取特定的耦合区域，使谐振器之间耦合系数满足绝对带宽不变的要求. 分别设计了工作在单端信号和差模信号下的滤波器. 结果表明，对于单端信号滤波器，其3 dB绝对带宽（|S₁₁| <-3 dB）在0.97 ~1.43 GHz的中心频率调节范围内约为80±4 MHz；对于差模信号滤波器，其3 dB绝对带宽（|S_dd11| <-3 dB）约为91±3 MHz，对共模噪声的抑制低于-20 dB.

Abstract: A novel tunable bandpass filter with constant absolute bandwidth (ABW) using double-sided parallel-strip lines (DSPSL) was proposed. The constant ABW can be realized by selecting a specific coupling region to control the coupling coefficient between resonators. Both a single-ended and a differential signaling bandpass filters were studied. For the single-ended case, its 3 dB ABW (|S₁₁| <-3 dB) is about 80±4 MHz as the center frequency tuned from 0.97 GHz to 1.43 GHz. For its differential counterpart, the 3 dB ABW (|S_dd11|<-3 dB) is about 91±3 MHz, and the suppression of common-mode noise is less than -20 dB.