针对射频MEMS滤波器的带外抑制能力较差和带内群延时不平坦的问题, 设计了一种窄带宽、低插损、高选择性的L波段射频MEMS线性相位滤波器。选取高介电常数的衬底材料实现窄带传输, 采用双层交指结构的谐振器实现线性相位, 减小了电路体积。利用HFSS软件对滤波器的性能进行优化。结果表明, 该滤波器的中心频率为1.46 GHz, 带内插入损耗＜1.97 dB, 带内群延时波动＜2 ns, 在中心频率左右1 GHz处的带外抑制＞70 dB。整体电路尺寸为10 mm×7.2 mm×0.62 mm。

To solve the problems of poor out-of-band suppression ability and uneven in-band group delay of RF MEMS filters, an L-band RF MEMS linear phase filter with narrow bandwidth, low insertion loss and high selectivity was designed. Narrow-band transmission was realized by selecting substrate material with high dielectric constant, and linear phase was realized by using resonator with double-layer inter-digital structure. The volume of the circuit was reduced. The HFSS software was used to optimize the performance of the filter. The results showed that the center frequency of the filter was 1.46 GHz, the in-band insertion loss was less than 1.97 dB, the in-band group delay fluctuation was less than 2 ns, and the out-of-band rejection was more than 70 dB at 1 GHz around the center frequency. The overall circuit size was 10 mm×7.2 mm×0.62 mm.