Laterally Actuated, Low Voltage, 3-Port RF MEMS Switch

The switch reported here for the first time was designed for an application in satellite based communications, where the requirements were for low actuation voltage, high isolation, good vibration and shock tolerance, and low power consumption. The functional requirement was for a single-pole, double throw (SPDT) switch. To satisfy the low voltage specification, thermal actuation was chosen, with mechanical latching to limit average power consumption. Thin-film microstrip transmission lines were fabricated on glass wafers for the signal path, while the actuators were fabricated in bonded silicon on insulator on a separate wafer, the final device being formed by bonding the two parts together. The SPDT functionality was achieved, the actuation voltage was 3V, and although insertion loss in these first prototypes was excessive, RF isolation was better than 50 dB across the 1 – 6 GHz range.