# US 10,481,672 B1 · Low-power MEMS wakeup system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,481,672 B1 - Document ID: US10481672B1 - Status: Granted - Kind: B1 - Application number: 16/274,455 - Filed: 2019-02-13 - Granted: 2019-11-19 - Earliest claimed: 2018-03-01 - Assignees: National Technology & Engineering Solutions of Sandia, LLC - Applicants: National Technology & Engineering Solutions of Sandia, LLC - Inventors: Benjamin Griffin; Robert William Reger; Sean Yen; Bryson Barney; Andrew Ian Young; Travis Ryan Young; Michael Wiwi; Michael David Henry; Brian D. Homeijer - Web page: https://patentgrep.com/patent/US10481672B1 ## CPC - G06F 1/325: {Power saving in peripheral device} - G01P 15/0922: {of the bending or flexing mode type} - G01P 15/097: by vibratory elements - G06F 1/3287: by switching off individual functional units in the computer system - H04R 3/002: {Damping circuit arrangements for transducers, e.g. motional feedback circuits} - H04R 17/02: Microphones - H04R 17/10: Resonant transducers, i.e. adapted to produce maximum output at a predetermined frequency - H04R 2201/003: Mems transducers or their use - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) - G01P: MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT (measuring or recording blood flow A61B5/02, A61B8/06; monitoring speed or deceleration of electrically-propelled vehicles B60L3/00; vehicle lighting systems adapted to indicate speed B60Q1/54; determining position or course in navigation, measuring ground distance in geodesy or surveying G01C; combined measuring devices for measuring two or more variables of movement G01C23/00; measuring velocity of sound G01H; measuring velocity of light G01J7/00; measuring direction or velocity of solid objects by reception or emission of radiowaves or other waves and based on propagation effects, e.g. Doppler effect, propagation time, direction of propagation, G01S; measuring speed of nuclear radiation G01T; measuring acceleration of gravity G01V; {measuring or recording the speed of trains B61L23/00; speed indicators incorporated in motor vehicles B60K35/00; measuring frequency or phase G01R; traffic control G08G}) - H04R: LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS (producing sounds with frequency not determined by supply frequency G10K) ## Abstract There is provided a near-zero-power wakeup system in which a MEMS sensor for mechanical or acoustic signals is coupled to a very-low-power complementary metal oxide semiconductor (CMOS) application-specific integrated circuit (ASIC). Power consumption can be minimized by operating the ASIC with sub-threshold gate voltages. ## Claims ### Claim 1 Apparatus comprising: a resonant MEMS device; and an integrated circuit electrically connected to the resonant MEMS device; wherein: the resonant MEMS device comprises a mass element suspended solely by flexures from a substrate; each of the flexures comprises a piezoelectric layer; the flexures are electrically connected to the integrated circuit such that in use, mechanically induced voltages in the flexures are coupled as input to the integrated circuit; and the integrated circuit comprises a comparator-latch circuit that produces a latched output voltage in response to an input signal that exceeds a threshold. ### Claim 2 (depends on 1) The apparatus of claim 1, wherein each of the tethers comprises a piezoelectric aluminum nitride layer overlying a layer of structural material. ### Claim 3 (depends on 1) The apparatus of claim 1, wherein each of the tethers comprises a piezoelectric aluminum nitride layer overlying a structural layer of single-crystalline silicon. ### Claim 4 (depends on 1) The apparatus of claim 1, wherein: the resonant MEMS device is conformed as a microphone in which the mass element is a diaphragm suspended by the flexures over a back cavity; the flexures are conformed to permit out-of-plane vibration of the suspended diaphragm; and the suspended diaphragm has a resonant frequency of vibration that lies within an operating frequency range of the apparatus. ### Claim 5 (depends on 4) The apparatus of claim 4, wherein the flexures are arranged circumferentially around the diaphragm, and wherein a vent is defined between each sequential pair of flexures. ### Claim 6 (depends on 5) The apparatus of claim 5, wherein the diaphragm is mass-loaded to reduce the resonant frequency. ### Claim 7 (depends on 6) The apparatus of claim 6, wherein the diaphragm is mass-loaded, at least in part, with additive material. ### Claim 8 (depends on 1) The apparatus of claim 1, wherein: the resonant MEMS device is conformed as an accelerometer in which the mass element is a suspended proof mass; the flexures are conformed to permit in-plane vibration of the suspended proof mass; and the suspended proof mass has a resonant frequency of vibration. ### Claim 9 (depends on 8) The apparatus of claim 8, wherein each of the flexures is folded at least twice. ### Claim 10 (depends on 1) The apparatus of claim 1, wherein the comparator-latch circuit comprises a comparator having an input, an output, and a positive feedback loop that latches the comparator by feeding the output back to the input. ### Claim 11 (depends on 1) The apparatus of claim 1, wherein the comparator-latch circuit comprises a plurality of long-channel CMOS transistors. ### Claim 12 (depends on 1) The apparatus of claim 1, wherein the resonant MEMS device is unpowered. ### Claim 13 (depends on 1) The apparatus of claim 1, wherein the resonant MEMS device and the integrated circuit constitute one of a plurality of sensor units, each of the sensor units has a latched output, and the latched outputs of the sensor units are combined in a logic circuit.