Low-noise multi axis MEMS accelerometer

A two-axis MEMS accelerometer, comprising:

• a substrate, which defines a substrate plane;
• a proof mass;
• and
• four comb capacitors comprising moveable comb electrodes extending from the proof mass and stationary comb electrodes anchored at a center of the substrate;
• wherein the proof mass is connected by springs to a plurality of suspenders that are anchored at the center of the substrate;
• wherein the four comb capacitors are arranged into two pairs of comb capacitors;
• wherein the comb capacitors in each pair of comb capacitors are mirror-images of each other reflected about an axis of reflection;
• wherein the axes of reflection of the two pairs of comb capacitors intersect at a central point of the substrate;
• wherein either comb capacitor in a first pair of comb capacitors comprises:
• a first set of moveable comb teeth that extend away from the proof mass in a first direction along a capacitor axis of the first pair of comb capacitors, the capacitor axis being parallel to the substrate plane;
• a second set of moveable comb teeth that extend away from the proof mass in a second direction, opposite the first direction, along the capacitor axis of the first pair of comb capacitors;
• a first set of stationary comb teeth opposite to and interdigitated with the first set of moveable comb teeth, wherein the first set of stationary comb teeth extend towards the proof mass in the second direction;
• and
• a second set of stationary comb teeth opposite to and interdigitated with the second set of moveable comb teeth, wherein the second set of stationary comb teeth extend towards the proof mass in the first direction;
• wherein either comb capacitor in a second pair of comb capacitors comprises:
• a first set of moveable comb teeth that extend away from the proof mass in a third direction along a capacitor axis of the second pair of comb capacitors, the capacitor axis of the second pair of comb capacitors being perpendicular to the capacitor axis of the first pair of comb capacitors;
• a second set of moveable comb teeth that extend away from the proof mass in a fourth direction, opposite the third direction, along the capacitor axis of the second pair of comb capacitors;
• a first set of stationary comb teeth opposite to and interdigitated with the first set of moveable comb teeth, wherein the first set of stationary comb teeth extend towards the proof mass in the fourth direction;
• and
• a second set of stationary comb teeth opposite to and interdigitated with the second set of moveable comb teeth, wherein the second set of stationary comb teeth extend towards the proof mass in the third direction;
• wherein in either comb capacitor in a first pair of comb capacitors, movement of the proof mass in the first direction causes an area of overlap between the first set of moveable comb teeth and first set of stationary comb teeth to increase and causes an area of overlap between the second set of moveable comb teeth and second set of stationary teeth to decrease, and wherein movement of the proof mass in the second direction causes an area of overlap between the first set of moveable comb teeth and first set of stationary comb teeth to decrease and causes an area of overlap between the second set of moveable comb teeth and second set of stationary teeth to increase;
• and
• wherein in either comb capacitor in a second pair of comb capacitors, movement of the proof mass in the third direction causes an area of overlap between the first set of moveable comb teeth and first set of stationary comb teeth to increase and causes an area of overlap between the second set of moveable comb teeth and second set of stationary teeth to decrease, and wherein movement of the proof mass in the fourth direction causes an area of overlap between the first set of moveable comb teeth and first set of stationary comb teeth to decrease and causes an area of overlap between the second set of moveable comb teeth and second set of stationary teeth to increase.