串联电容式RF-MEMS开关的研制

研制了一种高电容率的电容式RF-MEMS开关.与普通电容式开关设计不同的是,在CPW信号线上的绝缘层上表面覆盖了一层金属板,使开关在down-state时,上电极能与介质膜紧密接触,而在up-state时,金属板分别与上电极及信号线平面构成一组串联电容,大大降低了Cup值,从而提高了开关的电容率.与相同条件制得的普通电容式开关相比,其电容率要高出一个数量级,达到1000以上.由测试可知,所设计的串联电容式开关其隔离度在8GHz时可达42dB,明显优于普通电容式开关.

Designs and Analysis of Series Capacitive RF-MEMS Switches

This paper reports a capacitive switch with a high capacitance ratio.In contrast to conventional capacitive switches,the switch designed here has a metal film covering the dielectric on the signal line to ensure intimate contact with the dielectric film in the down state.The metal film can constitute two series capacitances versus the bridge and the signal line,so the up-capacitance can be lowered significantly.This allows further optimization of the down/up capacitance,with values more than 1000 over conventional designs under the same conditions.The switch designed here shows better isolation performance than conventional capacitive switches,with an isolation of 42dB at 8GHz.