Study of a bistable micromechanism for double throw RF switch applications

Bistable micromechanisms form the basis of a large class of latchable MEMS devices. In such systems, external power is required only to switch the system from one stable state to another stable state. This paper presents the study of a bistable micromechanism that is proposed to be used in the development of double throw RF switches. A lumped element equivalent of the compliant bistable micromechanism is analysed based on its elastic potential energy as a function the relevant linear displacement coordinate. Dimensions of a bistable micromechanism compatible with silicon bulk micromachining techniques are arrived at. The bistable actuator has a stroke of 10 µm. The force displacement curve for the system is obtained numerically. The forward and reverse critical driving forces, are 0.04 mN and −0.1 mN respectively. These forces which are within the capability of electrothermal actuation.