Patent ID: 11677337

Abstract:
A comb drive for MEMS device includes a stator and a rotor displaceable relative to the stator in a first direction. The stator includes stator comb fingers and the rotor includes rotor comb fingers. The stator comb fingers are coupled to two high impedance nodes to form high impedance node domains arranged in the first direction. The rotor comb fingers are coupled to two oppositely biased electrodes to form oppositely biased domains. Pairs of capacitors with opposite acoustic polarity are respectively formed between the high impedance node domains and the oppositely biased domains. The comb drive of the present invention has increased electrostatic sensitivity for a given unit cell cross-sectional area whilst maintaining an acceptable capacitance and linearity of voltage signal vs displacement. Extra force shim unit cells may be used, which allows for the stiffness between the rotor and stator to be controlled and reduced to zero for a particular displacement range, without impacting sensitivity.