Robert Boschgmbh

Akustica, Inc.

John Matthew Muza

Philip Sean Stetson

Michael James Daley

Matthew A Zeleznik

Sucheendran Sridharan

Brett Mathew Diamond

Anthony T Zisko

Franz Laermer

Andrew Jonathan Doller

Joseph Robert Fitzgerald

John William Zinn

Davin Luther Yuknis

Phillip Sean Stetson

Systems and methods for electrical testing of noise in a multi-membrane micro-electro-mechanical systems (MEMS) microphone are disclosed. The MEMS system has a test mode that includes placing the microphones' MEMS biasing networks into a reset mode, adjusting the first bias voltage for the first MEMS sensor such that a polarity matches the polarity of the bias voltage of the second MEMS sensor. The MEMS biasing networks are then placed into a sense mode, and a total noise value is obtained for the MEMS microphone system by measurement of the output of the system's preamplifier.

System and method for all electrical noise testing of MEMS microphones in production

Systems and methods are presented for power supply noise cancellation in a microphone package. A first node on a MEMS microphone package is coupled to an inverted voltage signal of a power supply output. A summing node is connected to both the first node and a second node. The second node is coupled to a non-inverted voltage signal of the power supply output. Because the parasitic capacitance of the MEMS microphone package is substantially equivalent relative to both the first node and the second node, the summing node outputs a noise-reduced summed voltage signal. An adjustable trim module is coupled to the first node and configured to adjust a reduction of a power supply noise in the summed voltage signal from the summing node.

Elimination of 3D parasitic effects on microphone power supply rejection

Systems and methods for preventing electrical leakage in a MEMS microphone. In one embodiment, the MEMS microphone includes a semiconductor substrate, an electrode, a first insulation layer, and a doped region. The first insulation layer is formed between the electrode and the semiconductor substrate. The doped region is implanted in at least a portion of the semiconductor substrate where the semiconductor substrate is in contact with the first insulation layer. The doped region is also electrically coupled to the electrode.

Doped substrate regions in MEMS microphones

A MEMS capacitive sensor biasing circuit. The circuit includes a high-voltage (HV) NMOS switch, an inductor, a diode, and a capacitor. The HV NMOS switch has a source coupled to ground. The inductor has a first node coupled to a drain of the HV NMOS switch, and a second node coupled to a DC power source supplying a first DC voltage. The diode has an anode coupled to the first node of the inductor and the drain of the HV NMOS switch. The capacitor has a first node coupled to a cathode of the diode, and a second node coupled to the ground.

MEMS capacitive sensor biasing circuit including an integrated inductor

Methods and system are described for cancelling interference in a microphone system. A positive bias voltage is applied to a first microphone diaphragm and a negative bias voltage is applied to a second microphone diaphragm. The diaphragms are configured to exhibit substantially the same mechanical deflection in response to acoustic pressures received by the microphone system. A differential output signal is produced by combining a positively-biased output signal from the first microphone diaphragm and a negatively-biased output signal from the second microphone diaphragm. This combining cancels common-mode interferences that are exhibited in both the positively-biased output signal and the negatively-biased output signal.

Differential microphone with dual polarity bias

Systems and methods of generating independent adjustable bias voltages for a differential microphone. The microphone system includes a positive adjustable charge pump, a positive sense capacitor, a negative adjustable charge pump, a negative sense-capacitor, and a differential amplifier. The positive adjustable charge pump is configured to generate a positive bias voltage. The positive sense-capacitor is configured to generate a positive sense voltage based on acoustic pressure from a first direction and the positive bias voltage. The negative adjustable charge pump is configured to generate a negative bias voltage. The negative sense-capacitor is configured to generate a negative sense voltage based on the acoustic pressure from the first direction and the negative bias voltage. The differential amplifier is configured to receive the positive and negative sense voltages. The differential amplifier is also configured to generate a differential voltage based on the positive and negative sense voltages.

Independently charge pumps for differential microphone

A MEMS microphone package is described that includes a first node and a second node having nearly equivalent 3D parasitic capacitances relative to a preamplifier of the microphone package, such that any noise generated on the first node is equivalent to any noise generated on the second node. An external power supply is connected to the first node and provides a bias voltage signal to the MEMS microphone package via the first node. An inverting amplifier is connected between the power supply and the second node. A third node is connected to the first node through a packaging parasitic capacitor, while the second node is connected to the third node through either an intended parasitic capacitor or an explicit capacitor. The noise coupled from the external power supply to the third node is then cancelled by summing the inverted power supply noise into the third node.

A system and method for controlling and adjusting a low-frequency response of a MEMS microphone. The system comprising the MEMS microphone, a controller, and a memory. The MEMS microphone includes a membrane and a plurality of air vents. The membrane configured such that acoustic pressures acting on the membrane cause movement of the membrane. The plurality of air vents are positioned proximate to the membrane. Each air vent of the plurality of air vents are configured to be selectively positioned in an open position or a closed position. The controller determines an integer number of air vents to be placed in the closed positioned, and generate a signal that causes the integer number of air vents to be placed in the closed position and causes any remaining air vents to be placed in the open position.

Digital acoustic low frequency response control for MEMS microphones

An adjustable charge pump system. The system includes a voltage regulator, a clock circuit, a voltage adjustment circuit, and a charge pump. The voltage regulator is configured to receive an input voltage and output a regulated voltage. The clock circuit is coupled to the voltage regulator and receives the regulated voltage. The voltage adjustment circuit is coupled to the voltage regulator and is configured to receive the regulated voltage and to output a driver voltage. The charge pump includes a plurality of stages. The output of the adjustable charge pump system is adjusted by disabling one or more stages of the first stage and the plurality of subsequent stages.

Adjustable biasing circuits for MEMS capacitive microphones

Charge pump capacitor assemblies and methods of manufacturing the same. One charge pump capacitor assembly includes a charge pump capacitor and a silicon substrate. The charge pump capacitor includes: a silicon-based charge pump capacitor oxide layer, a first terminal on a first side of the silicon-based charge pump layer, a second terminal on a second side of the silicon-based charge pump capacitor oxide layer opposite the first side, and a field oxide layer mounted adjacent the second terminal. The charge pump capacitor is coupled to the silicon substrate. The silicon substrate is etched to reduce contact between the silicon substrate and the field oxide layer.

Charge pump capacitor assembly with silicon etching

Systems and methods for adjusting a bias voltage and gain of the microphone to account for variations in a thickness of a gap between a movable membrane and a stationary backplate in a MEMS microphone due to the manufacturing process. The microphone is exposed to acoustic pressures of a first magnitude and a sensitivity of the microphone is evaluated according to a predetermined sensitivity protocol. The bias voltage of the microphone is adjusted when the microphone does not meet the sensitivity protocol. The microphone is then exposed to acoustic waves of a second magnitude that is greater than the first magnitude and a stability of the microphone is evaluated according to a predetermined stability protocol. The bias voltage and the gain of the microphone are adjusted when the microphone does not meet the stability protocol.

Trim method for CMOS-MEMS microphones

A micro-speaker. The micro-speaker includes a first plate, a second plate, and a diaphragm. The first plate is biased to a first voltage. The second plate is biased to a second voltage. The diaphragm is positioned between the first plate and the second plate and is configured to receive a digital signal. The digital signal causes the diaphragm to cycle between fully displaced toward the first plate and fully displaced toward the second plate, creating air pressure pulses that mimic the digital signal.

Class D micro-speaker

A semiconductor microphone including a silicon substrate having a perimeter; an N-well diffused into the substrate at the perimeter; a deformable diaphragm disposed over at least a portion of the silicon substrate and in contact with at least a portion of the perimeter; and a signal channel in electrical communication with the diaphragm. The signal channel includes a microphone output channel and a feedback output channel. The diaphragm produces an electric signal on the signal channel in response to deformation of the diaphragm and a portion of the electric signal is transmitted on the feedback output channel to the N-well.

Apparatus and method for driving parasitic capacitances using diffusion regions under a MEMS structure

A method of manufacturing a microphone using epitaxially grown silicon. A monolithic wafer structure is provided. A wafer surface of the structure includes poly-crystalline silicon in a first horizontal region and mono-crystalline silicon in a second horizontal region surrounding a perimeter of the first horizontal region. A hybrid silicon layer is epitaxially deposited on the wafer surface. Portions of the hybrid silicon layer that contact the poly-crystalline silicon use the poly-crystalline silicon as a seed material and portions that contact the mono-crystalline silicon use the mono-crystalline silicon as a seed material. As such, the hybrid silicon layer includes both mono-crystalline silicon and poly-crystalline silicon in the same layer of the same wafer structure. A CMOS/membrane layer is then deposited on top of the hybrid silicon layer.

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Venetia, PA, United States of America

John Matthew Muza