RF-MEMS Varactor With Minimal Contact
An innovative RF-MEMS varactor has been developed for use in distributed RF-MEMS circuits such as phase shifters and tunable matching networks where the capacitance ratio between on- and off- state must be limited to 2–10. By fabricating standoffs on the bottom side of the beam, this device eliminates the intimate contact between the FR-MEMS and dielectric, that is found in typical RF-MEMS beam capacitive switches. These standoffs limit the range of motion, allowing the capacitance ratio to be set, and also greatly reduces the contact area thus preventing stiction from occurring. The RF-MEMS switch has been fabricated with initial measurements demonstrating a capacitance ratio of 2.5. Preliminary reliability testing results demonstrate that this RF-MEMS design is very robust.