Zero-Level Packaged 5W CW RF-MEMS Switched Capacitors

This paper presents experimental results on RF-MEMS capacitors with improved power handling. A silicon nitride shell, protects the switched capacitor. A fixed RF-electrode is deposited above shell, and deflects the membrane upwards when a bias voltage is applied increasing the capacitance. The device can handle CW RF power, by using the high-resistivity silicon substrate as a counter electrode. By applying an appropriate bias voltage on the moveable electrode, the beam can be deflected towards the substrate, and counter the effects of RF Power. The key advantage of this structure is its ability to handle high power signals up to 5 W, under hot switching conditions, for more than 500 million cycles, without the need for high bias voltage. The proposed principle has been demonstrated on a 18.4-49.3 fF, 70×50μm² MEMS elementary switched capacitor, with control voltages less than 30 Volts.