超短波LTCC带通滤波器的设计与实现

Design and Realization of Ultra-short Wave Bandpass Filter Based on LTCC

设计了一款中心频率为244 MHz的超短波带通滤波器,该滤波器是基于低温共烧陶瓷（LTCC）技术实现。由于滤波器频率较低,波长较长,为了使其体积较小,结构也相对简单,在设计中采用半集总半分布结构来实现。通过调节各谐振单元之间的耦合,分别在阻带的低端和高端引入两个传输零点,从而有效地提高了滤波器的带外抑制。借助三维仿真软件进行优化仿真,设计出了一个具有四级谐振器、尺寸为4.5 mm×3.2 mm×1.5 mm的超短波带通滤波器。实测结果表明,输入输出电压驻波比〈1.5,带外抑制≥42 dB（340~1 000 MHz）,与设计仿真结果较为吻合。

This paper presents an ultra-short wave bandpass filter based on low temperature co-fired ceramic（LTCC） with the centre frequency at 244 MHz.Due to the low frequency and long wavelength of the filter,it is realized by semi-lumped and semi-distributed structure used in the design to make it smaller and more compact.By changing the coupling in resonant cells,two transmission zeros could be introduced at the lower or higher passband＇s skirt,so that the stopband rejection characteristics can be improved.At last an ultra-short wave bandpass filter with four coupled resonators is designed using 3-D simulation software,and the dimensions are 4.5 mm×3.2 mm×1.5 mm.Test results show that VSWR of the filter is lower than 1.5,attenuation ≥42 dB（340～1 000 MHz）.Good agreement is achieved between simulation and measurement results.