Knowles Electronics, Inc.

Michael Kuntzman

Sung Bok Lee

Vahid Naderyan

Michael Pedersen

Wade Conklin

Bing Yu

Peter V Loeppert

Yunfei Ma

Mohammad Shajaan

Venkataraman Chandrasekaran

Mohsin Nawaz

Faisal Zaman

Kim Spetzler Berthelsen

Mark Niederberger

Sandra Vos

Christian Lillelund

Ken Deng

Xin Song

Thomas Gautschi

A microphone device, an interface circuit and method are provided for managing a potential difference in sensitivity to a detected environmental stimulus associated with a sensor arrangement, where multiple electrical signals forming a differential signal can be produced, and the multiple electrical signals can be better balanced. Such an interface circuit, which can be used within a microphone device includes a bias voltage generator having one or more bias output voltage terminals, where a respective one of one or more DC bias voltages is produced at each of the bias output voltage terminals, for being coupled to a pair of transduction elements of a sensor. The interface circuit further includes an amplifier circuit having a first input terminal coupled to a first one of the pair of output terminals of the sensor and having a second input terminal coupled to a second one of the pair of output terminals of the sensor, the amplifier circuit producing a differential output signal. The interface circuit still further includes a compensation circuit coupled to the amplifier circuit for producing a balance signal based on an output signal being produced by the amplifier circuit, wherein the balance signal compensates for any difference in amplitude in the first and second electrical signals that are received by the amplifier circuit from the sensor.

Method and apparatus for balancing detection sensitivity in producing a differential signal

A method of forming an acoustic transducer comprises providing a substrate and depositing a first structural layer on the substrate. The first structural layer is selectively etched to form at least one of an enclosed trench or an enclosed pillar thereon. A second structural layer is deposited on the first structural layer and includes a depression or a bump corresponding to the enclosed trench or pillar, respectively. At least the second structural layer is heated to a temperature above a glass transition temperature of the second structural layer causing the second structural layer to reflow. A diaphragm layer is deposited on the second structural layer such that the diaphragm layer includes at least one of a downward facing corrugation corresponding to the depression or an upward facing corrugation corresponding to the bump. The diaphragm layer is released, thereby forming a diaphragm suspended over the substrate.

Methods of forming MEMS diaphragms including corrugations

A MEMS diaphragm assembly comprises a first diaphragm, a second diaphragm, and a stationary electrode assembly spaced between the first and second diaphragms and including a plurality of apertures disposed therethrough. Each of a plurality of pillars is disposed through one of the plurality of apertures and connects the first and second diaphragms. At least one of the first and second diaphragms is connected to the stationary electrode assembly at a geometric center of the assembly.

Dual-diaphragm assembly having center constraint

A microelectromechanical systems (MEMS) die includes a first diaphragm and a second diaphragm, wherein the first diaphragm and the second diaphragm bound a sealed chamber. A stationary electrode is disposed within the sealed chamber between the first diaphragm and the second diaphragm. A tunnel passes through the first diaphragm and the second diaphragm without passing through the stationary electrode, wherein the tunnel is sealed off from the chamber. The MEMS die further includes a substrate having an opening formed therethrough, wherein the tunnel provides fluid communication from the opening, through the second diaphragm, and through the first diaphragm.

MEMS device with perimeter barometric relief pierce

A microphone device includes a base and a microelectromechanical system (MEMS) transducer and an integrated circuit (IC) disposed on the base. The microphone device also includes a cover mounted on the base and covering the MEMS transducer and the IC. The MEMS transducer includes a diaphragm attached to a surface of the substrate and a back plate mounted on the substrate and in a spaced apart relationship with the diaphragm. The diaphragm is attached to the surface of the substrate along at least a portion of a periphery of the diaphragm. The diaphragm can include a silicon nitride insulating layer, and a conductive layer, that faces a conductive layer of the back plate. The MEMS transducer can include a peripheral support structure that is disposed between at least a portion of the diaphragm and the substrate. The diaphragm can include one or more pressure equalizing apertures.

Microphone device with ingress protection

An acoustic transducer for generating electrical signals in response to acoustic signals, comprises a first diaphragm having a first corrugation formed therein. A second diaphragm has a second corrugation formed therein, and is spaced apart from the first diaphragm such that a cavity having a pressure lower than atmospheric pressure is formed therebetween. A back plate is disposed between the first diaphragm and the second diaphragm. One or more posts extend from at least one of the first diaphragm or the second diaphragm towards the other through the back plate. The one or more posts prevent each of the first diaphragm and the second diaphragm from contacting the back plate due to movement of the first diaphragm and/or the second diaphragm towards the back plate. Each of the first corrugation and the second corrugation protrude outwardly from the first diaphragm and the second diaphragm, respectively, away from the back plate.

Acoustic transducers with a low pressure zone and diaphragms having enhanced compliance

An acoustic transducer comprises a transducer substrate having an aperture defined therethrough. At least one diaphragm is disposed on the transducer substrate over the aperture. A back plate is disposed on the transducer substrate and axially spaced apart from the at least one diaphragm. A perimetral support structure is disposed circumferentially between the at least one diaphragm and the back plate at a radially outer perimeter of the back plate. A plurality of perimetral release holes are defined circumferentially through at least one of the at least one diaphragm or the back plate proximate to and radially inwards of the perimetral support structure, at least a portion of the plurality of perimetral release holes defining a non-circular shape.

Acoustic transducers having non-circular perimetral release holes

An acoustic transducer for generating electrical signals in response to acoustic signals includes a transducer substrate, a back plate, and a diaphragm assembly. The diaphragm assembly includes a first diaphragm and a second diaphragm coupled thereto. The second diaphragm is positioned closer to the back plate than the first diaphragm. The second diaphragm includes a plurality of diaphragm apertures configured to allow air to pass through the second diaphragm. Each of the back plate and the first diaphragm are coupled to the transducer substrate at their periphery. In an embodiment, the transducer includes a post coupled to the first diaphragm and the second diaphragm, the post configured to prevent movement of the second diaphragm relative to the first diaphragm in a direction substantially perpendicular to the second diaphragm.

Acoustic transducer with reduced damping

Acoustic transducers for generating electrical signals in response to acoustic signals are disclosed. In some embodiments, an acoustic transducer includes an at least partially evacuated hermetically sealed cavity defined in part by a first diaphragm. The acoustic transducer also includes a backplate disposed at least partially within the cavity. The cavity having a pressure lower than atmospheric pressure. The acoustic transducer further includes a pressure sensor coupled to the backplate and configured to sense the pressure in the cavity.

Acoustic transducers with a low pressure zone and diaphragms having a pressure sensor

A microphone assembly includes an acoustic transducer having a back plate and a diaphragm, such that a surface of the back plate includes a plurality of holes. At least a portion of the plurality of holes are arranged in a non-uniform pattern. The non-uniform pattern includes holes of varying sizes spaced apart from neighboring holes by varying distances. The microphone assembly further includes an audio signal electrical circuit configured to receive an acoustic signal from the acoustic transducer.

Systems and methods for acoustic hole optimization

A microphone assembly comprises a substrate and an enclosure disposed on the substrate. A port is defined in one of the substrate or the enclosure. An acoustic transducer is configured to generate an electrical signal in response to acoustic activity. The acoustic transducer comprises a membrane separating a front volume from a back volume of the microphone assembly. The front volume is in fluidic communication with the port, and the back volume is filled with a first gas having a thermal conductivity lower than a thermal conductivity of air. An integrated circuit is electrically coupled to the acoustic transducer and configured to receive the electrical signal from the acoustic transducer. At least a portion of a boundary defining at least one of the front volume or the back volume is configured to have compliance so as to allow pressure equalization. The first gas is different from the second gas.

Systems and methods for reducing noise in microphones

A microphone assembly includes an acoustic transducer and an audio signal electrical circuit configured to receive an output signal from the acoustic transducer. The output signal includes an audio signal component and a tracking signal component. The audio signal component is representative of an acoustic signal detected by the acoustic transducer and the tracking signal component is based on an input tracking signal applied to the acoustic transducer. The audio signal electrical circuit includes an analog to digital converter configured to convert the output signal into a digital signal, an extraction circuit configured to separate the tracking signal component and the audio signal component from the digital signal, an envelope estimation circuit configured to estimate a tracking signal envelope from the tracking signal component, and a signal correction circuit configured to reduce distortion in the audio signal component using the tracking signal envelope.

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Chicago, IL, United States of America

Michael Kuntzman