Abstract: A bi-directional photoacoustic gas sensor includes a first photoacoustic cell, where an electromagnetic radiation source emits radiation to interact with an external gas and generate pressure waves that are detected by a MEMS diaphragm. A second photoacoustic cell has an interior volume and acoustic compliance that corresponds to the interior volume and acoustic compliance of the first photoacoustic cell. Processing circuitry within a substrate uses a first acoustic signal, received by the first photoacoustic cell, and a second acoustic signal, received by the second photoacoustic cell, to determine a bi-directional response of the gas sensor to remove noise and improve the sensor's signal-to-noise ratio.

Abstract: Embodiments for constant charge or capacitance for capacitive micro-electro-mechanical system (MEMS) sensors are presented herein. A MEMS device comprises a sense element circuit comprising a bias resistance, a charge-pump, and a capacitive sense element comprising an electrode and a sense capacitance. The charge-pump generates, at a bias resistor electrically coupled to the electrode, a bias voltage that is inversely proportional to a capacitance value comprising a value of the sense capacitance to facilitate maintenance of a nominally constant charge on the electrode. A sensing circuit comprises an alternating current (AC) signal source that generates an AC signal at a defined frequency; and generates, based on the AC signal, an AC test voltage at a test capacitance that is electrically coupled to the electrode. The sense element circuit generates, based on the AC test voltage at the defined frequency, an output signal representing the value of the sense capacitance.

Abstract: A piezoelectric micromachined ultrasonic transducer (PMUT) device includes a substrate having an opening therethrough and a membrane attached to the substrate over the opening. An actuating structure layer on a surface of the membrane includes a piezoelectric layer sandwiched between the membrane and an upper electrode layer. The actuating structure layer is patterned to selectively remove portions of the actuating structure from portions of the membrane to form in a central portion proximate a center of the open cavity and three or more rib portions projecting radially outward from the central portion.

Abstract: An algorithm and architecture for sense transfer function estimation injects one or more test signals from a signal generator into a MEMS gyroscope to detect an output signal (e.g., proof mass output sense signal), including an in-phase (e.g., Coriolis) component and a quadrature component. The in-phase and quadrature components are encoded with reference signals to determine phase and/or gain variation and are processed via a variety of components (e.g., matrix rotation, digital gain, tones demodulator, transfer function errors estimation, etc.) to estimate a sense transfer function of the MEMS (e.g., Hs(fd)) and corresponding phase and/or gain offset of Hs(fd). The in-phase and quadrature components are also compensated for phase and/or gain offset by system components.

Abstract: A robotic cleaning appliance includes a housing to which is coupled a surface treatment item and a sensor assembly with first and second transducers and an acoustic interface. The first sonic transducer transmits sonic signals through an acoustic interface and out of a first acoustic opening toward a surface beneath the robotic cleaning appliance. The sonic signals reflect from the surface as corresponding returned signals received by the second sonic transducer via a second acoustic opening port of the acoustic interface. A first annular ring is defined around the first acoustic opening port and a second annular rings is defined around the second acoustic opening port. The annular ring attenuate direct path echoes between the acoustic opening ports. The first and second acoustic opening ports are coupled the first and sonic transducers, respectively, via first and second horns; and the horns are tilted from orthogonal with the surface.

Abstract: A method includes forming a bumpstop from a first intermetal dielectric (IMD) layer and forming a via within the first IMD, wherein the first IMD is disposed over a first polysilicon layer, and wherein the first polysilicon layer is disposed over another IMD layer that is disposed over a substrate. The method further includes depositing a second polysilicon layer over the bumpstop and further over the via to connect to the first polysilicon layer. A standoff is formed over a first portion of the second polysilicon layer, and wherein a second portion of the second polysilicon layer is exposed. The method includes depositing a bond layer over the standoff.

Abstract: An interleaved cascaded integrator-comb (“CIC”) filter receives an interleaved sensor output signal, including a plurality of digitized sensor signals at an input clock rate. An integrator of the interleaved CIC filter processes the interleaved signal to output an integrated interleaved signal. A downsampler of the interleaved CIC filter buffers portions of the integrated interleaved corresponding to a decimation rate for the interleaved signal. The portions of the signals are provided to a comb filter, which outputs a decimated interleaved signal.

Abstract: Systems and methods for ultrasonic liquid level sensing. A circuit causes an ultrasonic transducer to transmit a sequence of ultrasonic pulses and receive a sequence of reflected signals. Each reflected signal includes at least one first reflection associated with at least one non-moveable surface and at least one second reflection associated with a moveable surface. A digital controller, for each reflected signal: determines at least one of a magnitude and a variance of the respective signal to form at least one output signal, identifies, in the at least one output signal, at least one first pulse indicative of the at least one non-moveable surface and at least one second pulse indicative of the moveable surface, and determines a distance of the moveable surface relative to the at least one non-moveable surface based on the identified first and second pulses.

Abstract: Acoustic and other activity detection signaling is provided herein. Operations of a method can include determining a micro-electromechanical system (MEMS) device is no longer in an initialization state and receiving a first signal that instructs the MEMS device to perform event activity detection. The method can also include receiving one or more event signals and determining that an event signal of one or more event signals satisfies a defined event characteristic. The method can also include outputting a second signal that comprises information indicative of a detection of event activity at the MEMS device being more than the defined event characteristic.

Abstract: Acoustic activity detection is provided herein. Operations of a method can include receiving an acoustic signal at a micro-electromechanical system (MEMS) microphone. Based on portions of the acoustic signal being determined to exceed a threshold signal level, output pulses are generated. Further, the method can include extracting information representative of a frequency of the acoustic signal based on respective spacing between rising edges of the output pulses.

Abstract: A dynamically balanced 3-axis gyroscope architecture is provided. Various embodiments described herein can facilitate providing linear and angular momentum balanced 3-axis gyroscope architectures for better offset stability, vibration rejection, and lower part-to-part coupling.

Abstract: An inertial sensor such as a MEMS accelerometer or gyroscope has a proof mass that is driven by a self-test signal, with the response of the proof mass to the self-test signal being used to determine whether the sensor is within specification. The self-test signal is provided as a non-periodic self-test pattern that does not correlate with noise such as environmental vibrations that are also experienced by the proof mass during the self-test procedure. The sense output signal corresponding to the proof mass is correlated with the non-periodic self-test signal, such that an output correlation value corresponds only to the proof mass response to the applied self-test signal.

Abstract: The teachings of the present disclosure enable the manufacture of one or more piezoelectric micromachined ultrasonic transducers (PMUTs) having a resonant frequency of a specific target value and/or substantially matched resonant frequencies. In accordance with the present disclosure, a flexible membrane of a PMUT is modified to impart a desired parameter profile for stiffness and/or mass to tune its resonant frequency to a target value. The desired parameter profile is achieved by locally removing or adding material to regions of one or more layers of the flexible membrane to alter its geometric dimensions and/or density. In some embodiments, material is added or removed non-uniformly across the structural layer to realize a material distribution that more strongly affects membrane stiffness than mass. In some embodiments, material having a specific residual stress is added to, and/or removed from, the membrane to define a desired modal stiffness for the membrane.

Abstract: A circuit for a feedback system incorporates a gating mechanism to reduce flicker noise (e.g., a source for bias instability within a MEMS device) at a digital output. The gating mechanism generates a gating pulse with a delay period (e.g., a common, or fixed, delay including symmetrical rising and falling edge delays) that overrides internal delays (e.g., asymmetrical rising and falling edge delays) of a phase generator to prevent propagation delay (e.g., delay affected by jitter) from reaching subsequent feedback components (e.g., a digital-to-analog converter (DAC)) and contributing to the generation of flicker noise within the system.

Abstract: The present invention relates to a microelectromechanical system (MEMS) microphone array capsule. In one embodiment, a MEMS microphone includes a MEMS microphone die; an acoustic sensor array formed into the MEMS microphone die, the acoustic sensor array comprising a plurality of MEMS acoustic sensor elements, wherein respective ones of the plurality of MEMS acoustic sensor elements are tuned to different resonant frequencies; and an interconnect that electrically couples the acoustic sensor array to an impedance converter circuit.

Abstract: A device includes a microelectromechanical system (MEMS) sensor die comprising a deformable membrane, a MEMS heating element, and a substrate. The MEMS heating element is integrated within a same layer and a same plane as the deformable membrane. The MEMS heating element surrounds the deformable membrane and is separated from the deformable membrane through a trench. The MEMS heating element is configured to generate heat to heat up the deformable membrane. The substrate is coupled to the deformable membrane.

Abstract: A device includes a substrate and an intermetal dielectric (IMD) layer disposed over the substrate. The device also includes a first plurality of polysilicon layers disposed over the IMD layer and over a bumpstop. The device also includes a second plurality of polysilicon layers disposed within the IMD layer. The device includes a patterned actuator layer with a first side and a second side, wherein the first side of the patterned actuator layer is lined with a polysilicon layer, and wherein the first side of the patterned actuator layer faces the bumpstop. The device further includes a standoff formed over the IMD layer, a via through the standoff making electrical contact with the polysilicon layer of the actuator and a portion of the second plurality of polysilicon layers and a bond material disposed on the second side of the patterned actuator layer.

Abstract: A microelectromechanical (MEMS) sensor, such as an accelerometer, has one more proof masses that respond to movement of the sensor, the movement of which is measured based on a distance between the one or more proof masses and on one or more sense electrodes. The accelerometer also has a plurality of auxiliary electrodes and a signal generator configured to apply an auxiliary signal having a first harmonic frequency to the plurality of auxiliary electrodes. Circuitry receives a sensed signal from the plurality of sense electrodes and identifies a portion of the sensed signal having the first harmonic frequency. Based on this identified portion of the sensed signal, the circuitry determines whether a residual voltage is present on the one or more proof masses or on the one or more sense electrodes, and the circuitry modifies the operation of the accelerometer when the residual voltage is determined to be present in order to compensate for the residual voltage.

Abstract: The present invention relates to a fixed-fixed membrane for a microelectromechanical system (MEMS) microphone. In one embodiment, a MEMS acoustic sensor includes a substrate; a membrane situated parallel to the substrate; and at least one vent formed into the membrane, wherein the at least one vent is a curved opening in the membrane, and wherein the at least one vent is disposed substantially along a length of the membrane.

Abstract: An ultrasonic transducer device comprises a piezoelectric micromachined ultrasonic transducer (PMUT), a transmitter with first and second differential outputs, and a controller. The PMUT includes a membrane layer. A bottom electrode layer, comprising a first bottom electrode and a second bottom electrode, is disposed above the membrane layer. The piezoelectric layer is disposed above the bottom electrode layer. The top electrode layer is disposed above the piezoelectric layer and comprises a segmented center electrode disposed above a center of the membrane layer and a segmented outer electrode spaced apart from the segmented center electrode. The controller, responsive to the PMUT being placed in a transmit mode, is configured to couple the first and second segments of the bottom electrode layer with ground, couple the first output of the transmitter with the segments of the segmented center electrode, and couple the second output with the segments of the segmented outer electrode.