Mems sensor with dual pendulous proof masses
AssigneeApple Inc.
InventorsChristopher C. Painter, Te Hsi Lee
Life of this patent
Estimating the term…
Abstract
A MEMS sensor is disclosed that includes dual pendulous proof masses comprised of sections of different thickness to allow simultaneous suppression of vertical and lateral thermal gradient-induced offsets in a MEMS sensor while still allowing for the normal operation of the accelerometer. In an embodiment, the structure and different sections of the MEMS sensor is realized using multiple polysilicon layers. In other embodiments, the structure and different thickness sections may be realized with other materials and processes. For example, plating, etching, or silicon-on-nothing (SON) processing.
Claims12
A micro-electromechanical systems (MEMS) sensor, comprising:
- a substrate;
- a first electrode and a second electrode having a first polarity disposed on, or formed in, the substrate;
- a third and fourth electrode having a second polarity opposite the first polarity, disposed on, or formed in the substrate;
- an anchor disposed on the substrate;
- a first pendulous mass rotatably coupled to the anchor having a heavy side and a light side, the heavy side having more mass then the light side, the first pendulous mass serving as a first common electrode and positioned to form a first gap between the first electrode and the first pendulous mass and a second gap between the second electrode and the first pendulous mass, the first pendulous mass configured to rotate about the anchor in a first direction when the first pendulous mass is subjected to an acceleration force;
- and
- a second pendulous mass rotatably coupled to the anchor having a heavy side and a light side, the heavy side having more mass then the light side, the second pendulous mass serving as a second common electrode and positioned to form a third gap between the third electrode and the second pendulous mass and a fourth gap between the fourth electrode and the second pendulous mass, the second pendulous mass configured to rotate about the anchor in a second direction that is opposite the first direction when the second pendulous mass is subjected to the acceleration force.
An electronic system comprising:
- a micro-electromechanical systems (MEMS) sensor configured to sense acceleration of the electronic system, the MEMS sensor including dual pendulous masses having sections of different thickness and a readout circuit configured to:
- convert a change in differential capacitance between electrodes of the MEMS sensor to differential voltage signals;
- process the differential voltage signals to remove lateral, thermal gradient-induced offset;
- and
- calculate acceleration data based on the processed differential voltage signals;
- one or more processors;
- memory coupled to the one or more processors and storing instructions that when executed by the one or more processors, cause the one or more processors to perform operations comprising:
- obtaining the acceleration data;
- calculating a location of the electronic system using the acceleration data;
- and
- displaying the location on a display device of the electronic system.
Dependencies are inferred from the claim text.