摘要
提出了一种椭圆低通可调滤波器的调谐方法,即通过调节第一传输零点(FTZ)来改变3dB截止频率Tc。解析计算表明,小范围内改变FTZ既可调节Tc和滚降速率,又能保证通带和阻带的特性基本不变。作者提出FTZ的移动可由串联谐振支路处容性MEMS开关的分布加载来实现,并基于微扰法求出器件中心谐振频率及特性的变化规律。本文相应设计了Tc为16GHz的7阶步进式滤波器。高频有限元全波仿真表明,每加载一个MEMS开关,Tc改变约1.5GHz,损耗特性则几乎不变。这证明了理论分析方法有较高的准确性,而且器件设计具有数字化调节能力和较出色的微波性能。这种方法也可用于高通和带通滤波器。论文还介绍了器件的体硅微加工流程及MEMS开关的初步加工结果。
This paper presents the analysis, designing and microfabrication of a tunable elliptic filter tuned by adjusting the first transmission zero （FTZ）. Analytical calculation indicates that the shift of FTZ can effectively move 3dB cutoff frequency, which can be implemented with a series of bulk-micromachined switches （binary varactor） distributed along the series resonance branch of the device. A micro-perturbation method is proposed to analyse theoretically the tuning method. A 7-order stepped tunable eclipse low- pass filter is designed with a cutoff frequency of 16 GHz. Full-wave FEA revealed a shift of about 1.5 GHz is achieved with the actuation of each MEMS switch and no other property variations are observed, which demonstrates the accuracy and effectiveness of the analytical method and proves that the filter design owns flexible tunability and excellent microwave performance. The bulk micromachining process and the initial results of the switch are also reported.
出处
《传感技术学报》
CAS
CSCD
北大核心
2008年第3期486-489,共4页
Chinese Journal of Sensors and Actuators
基金
国家自然科学基金资助(60501007)
北京市科技新星计划资助(2006A44)
北京市教委科技发展计划项目资助(KM200610772003)
北京市委组织部北京市优秀人才培养资助个人项目资助(20061D0500700168)
关键词
射频微机电系统
可调谐滤波器
椭圆低通滤波器
第一传输零点
频率移动
体硅微机械加工工艺
radio frequency micro electromechanical system （ RF MEMS）
tunable filter
elliptic filter
first transmission zero
frequency shift
bulk micromachining
