Compliant stops for mems inertial device drive PLL stability

A MEMS inertial transducer device coupled to a phase-look loop (PLL) circuit, wherein the MEMS inertial transducer device comprises:

• a MEMS inertial transducer;
• a drive actuation unit coupled to the MEMS inertial transducer;
• a drive measurement unit coupled to MEMS inertial transducer;
• and
• the phase-look loop (PLL) circuit;
• wherein the MEMS inertial transducer comprises:
• a substrate;
• a proof mass positioned in spaced apart relationship above a surface of the substrate;
• one or more substrate-anchored compliant members coupled to said proof mass and configured to enable the proof mass to laterally oscillate over the surface of the substrate with an oscillation frequency;
• a substrate-anchored over-travel stop structure positioned in relation to the proof mass at a first spacing distance to physically prevent lateral movement of the proof mass past a specified over-travel distance;
• and
• one or more compliant stop structures positioned in relation to the one or more substrate-anchored compliant members to physically engage with lateral oscillating movement of the one or more substrate-anchored compliant members past a desired stroke travel distance without physically preventing lateral oscillating movement of the proof mass, thereby stiffening the one or more substrate-anchored compliant members to smooth changes in the oscillation frequency by the proof mass,
• where the one or more substrate-anchored compliant members comprise an interior folded beam spring structure formed within an opening of the proof mass and having an internal truss connecting the proof mass over a plurality of cantilevered beam extension elements to an anchor fixed to the substrate, and where the one or more compliant stop structures comprise one or more soft stop structures integrated with the one or more substrate-anchored compliant members to define a clearance distance between the interior folded beam spring structure and the proof mass so that the one or more compliant stop structures physically engage with lateral oscillating movement of the one or more substrate-anchored compliant members without physically preventing lateral oscillating movement of the proof mass,
• where the one or more soft stop structures comprise a pair of soft stop structures integrated with the internal truss and extending laterally from opposed ends of the truss to define the clearance distance between the interior folded beam spring structure and the proof mass.