Microphone distortion reduction

Patent metadata

Field	Value
Publication number	US-2018091900-A1
Application number	US-201615280607-A
Country	US
Kind code	A1
Filing date	Sep 29, 2016
Priority date	Sep 29, 2016
Publication date	Mar 29, 2018
Grant date	—

Abstract

Microphone distortion reduction is presented herein. A system can comprise: a processor; and a memory that stores executable instructions that, when executed by the processor, facilitate performance of operations, comprising: obtaining a pressure-in to voltage-out transfer function representing a distortion of an output of a microphone corresponding to a stimulus of a defined sound pressure level that has been applied to the microphone; inverting an equation representing the pressure-in to voltage-out transfer function to obtain an inverse transfer function; and applying the inverse transfer function to the output to obtain a linearized output representing the stimulus. In one example, the obtaining of the pressure-in to voltage-out transfer function comprises: creating an ideal sine wave stimulus comprising the amplitude and fundamental frequency of the time domain waveform; and generating the equation based on a defined relationship between the ideal sine wave stimulus and the time domain waveform.

First claim

1 . A system, comprising:
a processor; and a memory that stores executable instructions that, when executed by the processor, facilitate performance of operations, comprising:
obtaining a pressure-in to signal-out transfer function representing a distortion of an output signal of a microphone corresponding to an input stimulus of a defined sound pressure level (SPL) that has been applied to the microphone;
creating an ideal sine wave stimulus based on an amplitude of a time domain waveform representing the output signal and a fundamental frequency of the time domain waveform;
generating, based on a defined relationship between the ideal sine wave stimulus and the time domain waveform, an equation representing the pressure-in to signal-out transfer function representing the distortion of the output signal; and
inverting the equation to obtain an inverse transfer function for facilitating an application, by the microphone, of the inverse transfer function to the output signal to obtain a linearized output representing the input stimulus.

2 . The system of claim 1 , wherein the output signal is an output voltage, and wherein the obtaining comprises:
measuring the output voltage.

3 . The system of claim 1 , wherein the obtaining comprises:
deriving, during a simulation of a defined model of the microphone comprising production based parameters of the microphone, the output signal voltage.

4 . The system of claim 1 , wherein the obtaining comprises:
importing output data of the time domain waveform representing the output signal; and based on the output data, obtaining properties of the time domain waveform comprising the amplitude of the time domain waveform and the fundamental frequency of the time domain waveform.

5 . (canceled)

6 . The system of claim 1 , wherein the defined relationship represents a voltage difference between the ideal sine wave stimulus and the time domain waveform with respect to a defined alignment of respective phases of the ideal sine wave stimulus and the time domain waveform.

7 . The system of claim 1 , wherein the microphone comprises a micro-electro-mechanical system (MEMS) microphone.

8 . The system of claim 7 , wherein the MEMS microphone comprises:
a diaphragm that converts the SPL into an electrical signal; a single backplate capacitively coupled to a side of the diaphragm; and an electronic amplifier that buffers the electrical signal to generate the output signal.

9 . The system of claim 7 , wherein the MEMS microphone comprises:
a diaphragm that converts the SPL into an electrical signal; dual backplates capacitively coupled to respective sides of the diaphragm; and an electronic amplifier that buffers the electrical signal to generate the output signal.

10 . The system of claim 1 , wherein the distortion comprises odd-order harmonic distortion and even-order harmonic distortion.

11 . The system of claim 10 , wherein the distortion is not frequency dependent, and wherein the distortion is not time dependent.

12 . A micro-electro-mechanical system (MEMS) microphone, comprising:
a processor; and a memory that stores executable instructions that, when executed by the processor, facilitate performance of operations, comprising:
creating an ideal sine wave stimulus representing an output signal of the MEMS microphone with respect to an input stimulus of a defined sound pressure level (SPL) that has been applied to the MEMS microphone, wherein the ideal sine wave stimulus is based on an amplitude of a time domain waveform representing the output signal and a fundamental frequency of the time domain waveform;
deriving, based on a defined relationship between the ideal sine wave stimulus and the time domain waveform, an equation of a transfer function representing a distortion of the output signal; and
applying, based on the equation, a linearization filter to the output signal to obtain a linearized output representing the input stimulus.

13 . The MEMS microphone of claim 12 , wherein the output signal is an output voltage, and wherein the deriving the equation comprises:
obtaining output data of the time domain waveform representing the output voltage; and based on the output data, deriving properties of the time domain waveform comprising the amplitude of the time domain waveform and the fundamental frequency of the time domain waveform.

14 . (canceled)

15 . The MEMS microphone of claim 12 , further comprising:
a diaphragm that converts the SPL into an electrical signal; a single backplate capacitively coupled to a side of the diaphragm; and an electronic amplifier that buffers the electrical signal to generate the output signal.

16 . The MEMS microphone of claim 12 , further comprising:
a diaphragm that converts the SPL into an electrical signal; dual backplates capacitively coupled to respective sides of the diaphragm; and an electronic amplifier that buffers the electrical signal to generate the output signal.

17 . A method, comprising:
generating, by a system comprising a processor, a sine wave stimulus representing an output signal of a microphone with respect to an input stimulus that has been applied to the microphone, wherein the sine wave stimulus is based on an amplitude of a time domain waveform representing the output signal and a fundamental frequency of the time domain waveform; selecting, by the system based on a defined relationship between the sine wave stimulus and the time domain waveform, an equation of a transfer function representing a distortion of the output signal; and facilitating, by the system, an application, by the microphone, of an inversion of the equation to the output signal to obtain a linearized output representing the input stimulus.

18 . The method of claim 17 , wherein the generating the sine wave stimulus comprises:
obtaining data representing the output signal of the microphone; and generating the sine wave stimulus having the amplitude of the time domain waveform and the fundamental frequency of the time domain waveform.

19 . The method of claim 17 , wherein the output signal is a voltage output, and wherein the selecting comprises:
measuring, by the system, the voltage output.

20 . The method of claim 17 , wherein the output signal is a voltage output, and wherein the selecting comprises:
deriving, during a simulation of a defined model of the microphone based on defined production parameters corresponding to the microphone, the voltage output.

21 . The MEMS microphone of claim 12 , wherein the defined relationship represents a voltage difference between the ideal sine wave stimulus and the time domain waveform with respect to a defined alignment of respective phases of the ideal sine wave stimulus and the time domain waveform.

22 . The method of claim 17 , wherein the selecting comprises:
selecting the equation based on a voltage difference between the sine wave stimulus and the time domain waveform with respect to a defined alignment of respective phases of the sine wave stimulus and the time domain waveform.

Assignees

• Invensense Inc

Inventors

• Parker Jeremy
• Bharatan Sushil
• Ata Erhan Polatkan

Classifications

• H04R3/06 Primary

  of electrostatic transducers · CPC title

• H04R2201/003

  Mems transducers or their use · CPC title

• H04R19/04

  Microphones (H04R19/01 takes precedence) · CPC title

• H04R29/004

  for microphones (H04R29/007 takes precedence) · CPC title

• H04R19/01

  characterised by the use of electrets · CPC title