X波段MEMS可变电容的设计与制作

Design and Realization of X-Band MEMS Variable Capacitor

对一种适合于X波段通信系统的RF MEMS可变电容进行了结构设计和工艺实现。该电容用高阻硅作为衬底材料,采用凹形和T形梁结构,整个结构由金材料组成;静电驱动,采用驱动信号与微波信号分离的方法。用有限元分析软件Ansys对该电容进行了模拟,随着驱动电压的变化,电容上极板产生位移变化,电容值相应地发生变化;设计了相应的工艺流程,实现了X波段MEMS可变电容的工艺制作和测试,该工艺与集成电路工艺兼容。S参数测试结果表明,在9GHz时Q值可达32.5,电容调节范围为28.8%。

An X-band RF MEMS variable capacitor was presented. The capacitor was composed of four novel T shape beams linked with a large concave plate. The capacitor was fabricated on the high resistance Si substrate, and the structure was made of Au. Actuation signals were sepa- rated from microwave signals. The capacitor was simulated with Ansys which is a finite element analysis software. The spacing between two parallel plates was changed by electrostatic actuation applied voltage so that the capacitor could be tuned. The X-band MEMS variable capacitor was fabricated with surface micromachining process, which was compatible with the IC process. The S-parameters of the variable capacitor was measured. The results show that the quality factor is 32.5 and the tuning range is 28.8% at 9 GHz.