Stable multi-step capacitance control with binary voltage operation at +/-3V in integrated piezoelectric RF MEMS tunable capacitors

The design and operation technique for a stable capacitance control in piezoelectric RF MEMS tunable capacitors have been investigated. Four folded-beam capacitors composed of piezoelectric aluminum nitride thin films were integrated in the quadruple capacitor and each folded-beam capacitor showed uniform operation voltage of less than 3V. A stable multi-step capacitance control was realized with the binary voltage operation at +/-3V, where each capacitor could be handled at binary state of capacitance due to its saturation characteristics. Eight levels of capacitance value up to 1.5pF with a step of 0.13pF to 0.16pF were realized.