US Patent 8633635 Microelectromechanical resonators with thermally-actuated frequency tuning beams

A microelectromechanical resonator includes a resonator body anchored to a substrate by at least a pair of tethers that suspend the resonator body opposite an underlying opening in the substrate. A first thermally-actuated tuning beam is provided, which is mechanically coupled to a first portion of the resonator body that is spaced apart from the pair of tethers. The first thermally-actuated tuning beam is configured to induce a mechanical stress in the resonator body by establishing a thermal expansion difference between the first thermally-actuated tuning beam and the resonator body in response to a passing of current through the first thermally-actuated tuning beam.