Microelectromechanical system resonator devices and oscillator control circuits

A microelectromechanical systems (MEMS) device comprising:

• a MEMS resonator comprising:
• a central resonator element suspended by a plurality of anchor beams disposed at predetermined points on the periphery of the central resonator element in dependence upon the resonance mode the central resonator element is designed to resonate in;
• a plurality of electrostatic actuators disposed around the periphery of the central resonator element, each electrostatic actuator comprising a movable portion disposed towards the central resonator element, a fixed portion disposed distal to the central resonator element, and a spring disposed between the movable portion and the fixed portion;
• and
• a plurality of stoppers, each stopper disposed relative to the central resonator element and an electrostatic actuator of the plurality of electrostatic actuators to limit motion of the moveable portion of the electrostatic actuator of the plurality of electrostatic actuators towards the central resonator element;
• wherein
• the movable portions of the plurality of electrostatic actuators form gaps relative to the central resonator element defined by the minimum gap feature of manufacturing process employed to form the MEMS resonator which is larger than the gaps when the moveable portions of the plurality of electrostatic actuators are driven under electrostatic actuation into contact with the stoppers, which is limited only be manufacturing process employed.

A microelectromechanical systems (MEMS) device comprising:

• a MEMS resonator comprising a pair of sensing electrodes and a pair of driving electrodes;
• and
• the MEMS device further comprises:
• a fully differential transimpedance amplifier (TIA) providing a feedback loop between the sensing electrodes and the driving electrodes, the TIA comprising
• an input stage having differential inputs and differential outputs, wherein the differential inputs are coupled to the sensing electrodes of the MEMS resonator and the input stage employs a regulated cascade topology;
• a variable gain amplifier (VGA) having differential inputs and differential outputs, wherein the differential inputs of the VGA are coupled to the differential outputs of the input stage and the gain of the VGA is controlled by an automatic gain control (AGC) circuit;
• and
• an output stage having differential inputs and differential outputs, wherein the differential inputs of the output stage are coupled to the differential outputs of the VGA, the differential outputs of the output stage are coupled to the driving electrodes of the MEMS resonator and the output stage employs a super source follower.

A microelectromechanical systems (MEMS) device comprising:

• a MEMS resonator comprising:
• a piezoelectric MEMS resonator having a pair of sensing electrodes disposed on a first side of the piezoelectric MEMS resonator and a pair of driving electrodes disposed on a second side of the piezoelectric MEMS resonator;
• and
• a fully differential transimpedance amplifier (TIA) providing a feedback loop between the sensing electrodes and the driving electrodes, the TIA comprising
• an input stage having differential inputs and differential outputs, wherein the differential inputs are coupled to the sensing electrodes of the MEMS resonator and the input stage employs a regulated cascade topology;
• a variable gain amplifier (VGA) having differential inputs and differential outputs, wherein the differential inputs of the VGA are coupled to the differential outputs of the input stage and the gain of the VGA is controlled by an automatic gain control (AGC) circuit;
• and
• an output stage having differential inputs and differential outputs, wherein the differential inputs of the output stage are coupled to the differential outputs of the VGA, the differential outputs of the output stage are coupled to the driving electrodes of the MEMS resonator and the output stage employs a super source follower;
• wherein
• the piezoelectric MEMS resonator is coupled to the fully differential TIA on its inputs and outputs via capacitors;
• and
• the piezoelectric MEMS resonator is driven without any DC signal applied to it.

A microelectromechanical systems (MEMS) device comprising:

• a MEMS resonator;
• and
• either:
• a plurality of other MEMS resonators each operating over a predetermined first frequency range of a plurality of first frequency ranges;
• and
• a multiplexer coupled to the MEMS resonator and the plurality of other MEMS resonators;
• wherein
• the MEMS resonator operates over a predetermined second frequency range;
• and
• the MEMS device provides at least one of:
• an oscillator providing multiple output frequencies, each output frequency being within at least one of the plurality of first frequency ranges and the second frequency range;
• and
• a single output frequency over a bandwidth established by the plurality of first frequency ranges and the second frequency range;
• or:
• the MEMS resonator is one of a plurality of MEMS resonators each having a different resonant frequency;
• the plurality of MEMS resonators are coupled to a plurality of inputs of an electrical multiplexer;
• a control circuit provides at least one of power and control signals to the plurality of MEMS resonators;
• an output of the electrical multiplexer is coupled to a transimpedance amplifier;
• and
• the MEMS device provides a programmable output at one frequency of the plurality of different resonant frequencies of the plurality of MEMS resonators under an action of the control circuit.