新型三阶SIR高阻带抑制双通带滤波器

A novel tri-section SIR dual-band filter with high stopband rejection

采用三阶信噪比(signal to interference ratio,SIR)干扰谐振器作为基本谐振单元,通过调整阻抗比控制主频和第一杂散频率的位置,设计了一种新型高阻带抑制双通带滤波器.滤波器第一通带由主谐振频率产生,第二通带由第一杂散频率产生.运用三角耦合结构作为该滤波器的拓扑结构,使得整体滤波器呈现出带外传输零点和阻带的高抑制度.使用交指型耦合结构实现输入/输出端的强耦合,得到较高的外部品质因数.该滤波器的两个通带中心频率分别为1.57 GHz(GPS)和2.5 GHz(4G),3 d B带宽分别为4.0%和2.4%.结果表明,测量结果和仿真结果基本吻合.

A dual-band filter with high stopband rejection is designed using a tri-section signal to interference ratio （SIR） resonator. The center frequencies and first spurious frequencies of resonators can be controlled independently to design aspecific dual-band filter. The tri-section coupling structure is aimed at transmission zeros and high stopbands rejection. To get a high external quality factor, an inter-digital finger coupling structure is introduced. The filter has dual passband center frequencies of 1.57 GHz （GPS） and 2.5 GHz （4G）, with 3 dB fractional bandwidths of 4.0% and 2.4%, respectively. Measured results well agree with simulations.