US Patent 7339446 - Dual wafer MEMS resonator

http://www.freepatentsonline.com/7339446.html

One of the popular applications of MEMS devices is in tuning resonant circuits. This patent from Intel teaches forming the tuning MEMS portion on one substrate and the resonant circuitry on an opposite substrate which provides a reduction in the total lateral dimensions required for MEMS-based tunable filters.

1. An apparatus comprising: a resonator to resonate a radio frequency signal; a microelectromechanical system element to tune the resonator to a frequency, wherein the microelectromechanical system element is provided on a first wafer and the resonator is provided on a second wafer; a plurality of bonding pads to electrically bond the first and second wafers; and a plurality of seal rings to bond the plurality of bonding pads.