基于带状线的梳状线滤波器设计与实现

Design and implementation of comb line filter based on strip line

针对复杂射频传输环境下,高性能小型化滤波器的需求,在具有λ/8谐振线杆的梳状线滤波器基础上,研究电容加载对滤波器性能的影响,并采用带状线的结构方式,充分验证小型化的实现。设计了一款工作频率在2.1~3 GHz、通带内插入损耗小于2.2 dB、电压驻波比均低于1.5的梳状线滤波器,该滤波器在二倍频处平均抑制度在35 dBc以上。其优势在于将传输线布于基板内层,减少外界干扰,且便于装配使用,在小型化的基础上,实现更优的性能。引入的抽头式端口结构有效地调节了回波损耗,改善传输性能;其次,将集总端电容叠压在介质基板内部,利用多层基板结构,实现集成化、小型化。

In order to meet the requirement of high performance miniaturization filter in complex RF transmission environment, based on the comb-line filter with λ/8 resonant wire rod, the effect of capacitive loading on filter performance was studied, and the strip line structure was adopted to fully verify the miniaturization. A comb-line filter with operating frequency within the range of 2.1 to 3 GHz, passband insertion loss less than 2.2 dB and voltage standing wave ratio less than 1.5, is designed. The average suppression degree of this filter at twice frequency is above 35 dBc. Its advantages lie in that the transmission line is laid in the inner layer of the substrate, which reduces the external interference and is convenient for assembly and use. On the basis of miniaturization, better performance can be achieved. The tapped port structure can effectively adjust the return loss and improve the transmission performance. Secondly, the lumped capacitance is superimposed inside the dielectric substrate, and the multi-layer substrate structure is used to realize the miniaturization of integration.