Micromagnetic MEMS latches switch RF signals

MagLatch RF relays switch DC to 6-GHz signals in 50-Ω systems. Fabricated using a surface micromachining approach, the relays rely on the preferential-magnetization characteristic of a cantilever made of soft magnetic material (Fe-NI).

In a constant, nearly perpendicular magnetic field, such a cantilever can experience either a clockwise or a counter-clockwise torque, depending on the angle between it and the field, leading to bi-stable behavior. To change the switch's state, a second magnetic field (generated by a short current pulse through a coil) realigns the cantilever's magnetization, changing the magnetic-torque direction and causing the cantilever to flip. The static external field instantly latches the switch in its new position, which it maintains until arrival of a subsequent switching signal.

This simplified SPST configuration illustrates the operation of the commercially available SPDT versions.

According to Magfusion executive VP Chuck Wheeler, MagLatches don't exhibit the stiction that can plague electrostatic MEMS relays. He says a key advantage is that the devices preserve their states when powered off.

Edward Hopkins, Magfusion's VP for business development, says the company is targeting high-end applications such as automatic test equipment for initial applications of the devices, but he adds that, as the devices show promise for integration with other semiconductor devices, he expects them to also serve in high-volume consumer products, such as cell phones.