Microelectromechanical systems (MEMS) technology is coming of age in terms of reliability. The RMSW200 RF MEMS single-pole, single-throw switch offered by RadantMEMS (Stow, MA), for example, has been performance tested at 10 GHz for high reliability even over 100 billion switching cycles. The switch, which is designed for applications from DC to 40 GHz, also shaves insertion loss to a bare minimum compared to competing technologies, such as PIN-diode-based solid-state switches.
The company's MEMS switches are three-terminal devices that employ a cantilever beam. The switches are fabricated with an all-metal surface micromachining process on high-resistivity silicon. For environmental protection, the switches are hermetically sealed within wafer-scale packaging. A basic RadantMEMS switch configuration consists of a drain, source, gate, and beam (see figure). The beam is deflected by applying a voltage between the gate and source electrodes. The free end of the beam contacts the drain and completes an electrical path between the drain and the source. The company's switches are designed for actuation (gate) voltages from 40 to 120 V. At low frequencies, the on resistance has been measured at less than 1W, while the on-response switching time is about 5 s.
Performance testing conducted on an eight-contact MEMS switch with 0.5-W input power at 10 GHz revealed the device to be perfectly functional when the testing was stopped after 100 billion switching cycles. Both insertion loss and isolation remained stable over the life of the switch. For a switching rate of 1 kHz, the power consumption was a low 5 W.
The company's DC-to-40-GHz model RMSW200 SPST switch is among the highest-frequency commercial MEMS switches. It features less than 0.5 dB insertion loss to 38 GHz and better than 20 dB return loss to 36 GHz. Insertion loss is typically less than 0.27 dB at 2 GHz. The isolation is 20 dB at 10 GHz and 13 dB at 40 GHz.
The model RMSW100 SPST switch is designed for use from DC to 12 GHz. It features less than 0.15 dB insertion loss at 2 GHz and more than 25 dB isolation at 2 GHz, with better than 30-dB return loss at 2 GHz.