Large Throw Magnetic MEMS Actuated RF Switch

The design, fabrication and operation of a large (100 micron) throw magnetic actuator is described. The actuator is fabricated on a steel substrate using SU-8 which is an ultra thick photoresist. The SU-8 is used as a mould for fabrication of the copper coil and, when loaded with a ferromagnetic material, as the potcore and mover. Electromagnetic actuation results in a force that is up to 100 times greater than can be obtained electrostatically for the same physical size. Switching gaps up to 200 microns have been demonstrated and the actuators have lifetimes of more than 100,000 cycles. The actuator is designed to operate a MEMS RF switch, for example as an isolator where a large switch gap and high contact force are required to provide high isolation and low transmission loss in the "open" and "closed" states respectively.