宽阻带平面低通滤波器的设计  

Design of Broad-Stopband Planar Lowpass Filters

作　　者：宁俊松[1] 罗正祥[1] 羊恺[1] 补世荣[1] 刘娟秀[1] 

机构地区：[1]电子科技大学微波中心,四川成都610054

出　　处：《电子学报》2008年第2期342-345,共4页Acta Electronica Sinica

摘　　要：低通滤波器是通信系统中关键的器件之一，常作为选频器件用来抑制干扰信号和谐波信号，因此低通滤波器阻带带宽成为关键指标．常见的平面低通滤波器采用短截线（分支线）或高低阻抗线结构，这些结构的低通滤波器阻带不够宽，一般在截止频率的2倍频或3倍频处出现寄生通带．本文使用等效的T形节替代低通滤波器中的串联传输线的方式实现了带阻滤波器嵌入到低通滤波器内部，既对低通滤波器的阻带上任意频段出现的寄生通带进行了抑制，又不影响低通滤波器的通带内性能，并给出等效T形节的综合设计公式．此结构综合设计方法严谨简单、易于平面电路实现，制作出来改进的低通滤波器对3倍频寄生通带进行抑制，扩宽了阻带带宽到4个倍频程以上，测试结果：通带带宽0～3GHz，通带插入损耗小于0．5dB，带外抑制3．6～12GHz大于60dB．Conventional planar lowpass filters often suffer from the problem of spurious passbaads. For spurious response suppression, integration of bandstop filters in a conventional open-stub lowpass filter is presented. By using equivalent T-shaped transmission lines to replace series connecting transmission lines of the conventional lowpass filter,the T-shaped lines work as bandstop filters at the spurious passbands. Furthermore, general design equations are given to transform arbitrary series connecting lines of the filter into the equivalent T-shaped lines. The proposed filter improves the out-of-band rejection over very wide operation band width and reduces the overaU size with low insertion loss. Very good agreement has been observed between the expetirnental results and simulated data. The insertion loss is less than 0.5 dB from DC to 3GHz and the rejection is greater than 60 dB from 3.6GHz to 12GHz.

关 键 词：低通滤波器了 带阻滤波器 等效T形节 宽阻带 

分 类 号：TN713[电子电信—电路与系统]