一种基于LTCC的小型化吸收式带通滤波器的设计

Design of an Absorptive Bandpass Filter with Miniaturization Based on LTCC

提出了一种基于LTCC技术的新型小型化吸收式带通滤波器的实现方法。该吸收式滤波器基于耦合相消原理由两个四阶梳状线带通滤波器和两个3dB正交定向耦合器组成。为了减小实物体积,梳状线带通滤波器采用三层短路耦合线结构,耦合器采用两层蛇形宽边耦合带状线结构,并且上下放置两个梳状线带通滤波器。运用三维电磁仿真软件HFSS建模仿真,设计了一款吸收频带范围为2GHz^4GHz,滤波频带范围为2.85GHz^3.25GHz的吸收式带通滤波器,通带内插入损耗小于2dB,各端口驻波比优于1.4,在低阻带0GHz^2.55GHz和高阻带3.55GHz^5GHz内的衰减均大于30dB,体积仅为8.4mm×5mm×2.5mm。测试结果与HFSS仿真结果较为吻合。

A new implementation method of the miniaturized absorptive bandpass filter based on LTCC technology is proposed.The absorptive filter consists of two fourth-order comb-line bandpass filters and two 3 dB orthogonal directional couplers based on the coupled cancellation principle.In order to reduce the physical volume,comb-line bandpass filters adopt three-layer short-circuit coupled line structures,couplers adopt two-layer serpentine wide-edge coupled stripline structures,and two comb-line bandpass filters are placed above and below.By the three-dimensional electromagnetic simulation software HFSS modeling and simulating,an absorptive bandpass filter with an absorptive band range from 2 GHz to 4 GHz and a filtering band range from 2.85 GHz to 3.25 GHz is designed.The insertion loss in the passband is less than 2 dB,the VSWR of each port is better than 1.4,and the attenuation in the low stop band from0 GHz to 2.55 GHz and the high stop band from 3.55 GHz to 5 GHz is greater than 30 dB.The volume is only 8.4 mm×5 mm×2.5 mm.The measurement results show a good match with the HFSS simulation.