MEMS Sensor With Dynamically Variable Reference Capacitance

摘要

An MEMS device has a dynamically variable reference capacitor that provides a reference to a sense capacitance. In some embodiments, a 3-axis accelerometer includes a proof mass suspended above a substrate from an anchor, and a cantilevered Z-axis reference capacitor arm suspended above the substrate from the same anchor. In some embodiments, the proof mass is suspended from a plurality of anchors, and each anchor also supports one or more cantilevered arms, the cantilevered arms forming a dynamically variable reference capacitance.

主权项

1. A MEMS device comprising:
a substrate having a surface, the surface defining a Z-axis normal to the surface; an anchor extending from the surface in the direction of the Z-axis; a beam suspended from the anchor such that the beam is parallel to the surface, the beam forming a sense capacitance with the substrate; a dynamically variable reference capacitance, the reference capacitance providing a reference for the sense capacitance; and a sensing circuit electrically coupled to the sense capacitance and the dynamically variable reference capacitance, the sensing circuit configured to assess a difference between a charge on the sense capacitance and a charge on the reference capacitance.