WO2022110421A1

WO2022110421A1 - Mems microphone and working control method therefor

Info

Publication number: WO2022110421A1
Application number: PCT/CN2020/138835
Authority: WO
Inventors: 张金宇
Original assignee: 瑞声声学科技(深圳)有限公司
Priority date: 2020-11-30
Filing date: 2020-12-24
Publication date: 2022-06-02
Also published as: CN112492475B; CN112492475A

Abstract

The present application relates to the technical field of microphones, and in particular relate to a MEMS microphone and a working control method therefor. The MEMS microphone comprises a first MEMS microphone unit, a second MEMS microphone unit, and an ASIC chip. The sensitivity of the second MEMS microphone unit is greater than the sensitivity of the first MEMS microphone unit. The ASIC chip comprises a first amplifier, a first analog-to-digital converter, a second amplifier, a second analog-to-digital converter, and an output terminal electrically connected to the first analog-to-digital converter and the second analog-to-digital converter separately. In the MEMS microphone of the present application, a first MEMS microphone unit and a second MEMS microphone unit that have different sensitivities are provided to obtain two electrical signals that have different sensitivities, and then the two electrical signals are converted into two digital signals by two analog-to-digital converters respectively, which are superimposed and then outputted, thus achieving an ultra-large dynamic range, and achieving a high AOP while having a high signal-to-noise ratio.

Description

MEMS microphone and its working control method

【Technical field】

The present application relates to the technical field of microphones, and in particular, to a MEMS microphone and a working control method thereof.

【Background technique】

A MEMS microphone mainly includes a MEMS sensor and an ASIC (Application-Specific Integrated Circuit, application-specific integrated circuit) chip, which are electrically connected to convert a sound signal into an electrical signal to realize the function of the microphone.

Most of the MEMS microphones in the prior art amplify and output electrical signals through an amplifier in an ASIC chip, and cannot take into account both high signal-to-noise ratio and high AOP (Acoustic Overload Point, acoustic overload point).

Therefore, it is necessary to provide a new MEMS microphone to solve the above technical problems.

[Content of the invention]

The purpose of this application is to provide a MEMS microphone and a working control method thereof, so as to solve the technical problem that the MEMS microphone in the prior art cannot take both high signal-to-noise ratio and high AOP into consideration.

The technical solution of the present application is as follows: a MEMS microphone is provided, including a first MEMS microphone unit, a second MEMS microphone unit and an ASIC chip, wherein the sensitivity of the second MEMS microphone unit is greater than the sensitivity of the first MEMS microphone unit, so The ASIC chip includes a first amplifier electrically connected to the first MEMS microphone unit, a first analog-to-digital converter electrically connected to the first amplifier, a second amplifier electrically connected to the second MEMS microphone unit, a second analog-to-digital converter electrically connected to the second amplifier and an output terminal electrically connected to the first analog-to-digital converter and the second analog-to-digital converter, respectively.

Preferably, the first MEMS microphone unit is a first MEMS chip, and the second MEMS microphone unit is a second MEMS chip.

Preferably, the ASIC chip further includes a first bias voltage module for providing a bias voltage for the first MEMS chip and a second bias voltage module for providing a bias voltage for the second MEMS chip.

Preferably, the first MEMS microphone unit includes a first diaphragm, the second MEMS microphone unit includes a second diaphragm, and the first MEMS microphone unit and the second MEMS microphone unit are integrated into a third MEMS microphone on the chip.

Preferably, the input end of the first MEMS microphone unit and the input end of the second MEMS microphone unit are connected to each other and both are grounded.

Preferably, the first input end of the first amplifier is connected to the output end of the first MEMS microphone unit, the second input end of the first amplifier is grounded; the first input end of the second amplifier is connected to the The output end of the second MEMS microphone unit is connected, and the second input end of the second amplifier is grounded.

Another technical solution of the present application is as follows: to provide a working control method of a MEMS microphone, the MEMS microphone is the above-mentioned MEMS microphone, including:

The first MEMS microphone unit and the second MEMS microphone unit respectively convert the sound signal input to the MEMS microphone into a first electrical signal and a second electrical signal, wherein the sensitivity of the second electrical signal is greater than that of the first electrical signal. the sensitivity of the signal;

The first analog-to-digital converter converts the first electrical signal processed by the first amplifier into a first digital signal, and the second analog-to-digital converter converts the second electrical signal processed by the second amplifier into a second digital signal, wherein, The first analog-to-digital converter operates with a first clock signal, the second analog-to-digital converter operates with a second clock signal, and the first clock signal and the second clock signal have the same period and are delayed in phase one or more of said cycles;

The first digital signal and the second digital signal are superimposed and output.

Preferably, the first digital signal is in a high-order range, and the second digital signal is in a low-order range.

Preferably, the sensitivity of the first MEMS microphone unit is -68dBFS, the sensitivity of the second MEMS microphone unit is -20dBFS, and the dynamic range of the superimposed signal of the first digital signal and the second digital signal is - 144dBFS～0dBFS.

Preferably, the sound pressure of the superimposed signal of the first digital signal and the second digital signal is 18dBSPL˜162dBSPL.

The beneficial effect of the present application is that the MEMS microphone of the present application obtains two electrical signals with different sensitivities by setting the first MEMS microphone unit and the second MEMS microphone unit with different sensitivities, and then the two analog-to-digital converters respectively convert the two channels The electrical signal is converted into two digital signals, which are superimposed and output to achieve a large dynamic range and high AOP while having a high signal-to-noise ratio.

【Description of drawings】

1 is a schematic structural diagram of a MEMS microphone according to a first embodiment of the application;

FIG. 2 is a schematic structural diagram of a preferred implementation manner of the MEMS microphone according to the first embodiment of the application;

FIG. 3 is a working principle diagram of the MEMS microphone according to the first embodiment of the application;

FIG. 4 is a flowchart of a work control method of a MEMS microphone according to a second embodiment of the present application;

FIG. 5 is a schematic diagram of an operation control method of a MEMS microphone according to a second embodiment of the present application.

【Detailed ways】

In order to facilitate the understanding of the present utility model, the present utility model will be more fully described below with reference to the related drawings. The preferred embodiments of the present utility model are shown in the accompanying drawings. However, the present invention may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that a thorough and complete understanding of the present disclosure is provided.

It should be noted that when an element is referred to as being "fixed to" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which the present invention belongs. The terms used in the description of the present invention herein are only for the purpose of describing specific embodiments, and are not intended to limit the present invention.

first embodiment

Referring to FIGS. 1 to 3 , the MEMS microphone provided by the first embodiment of the present application includes a first MEMS microphone unit 10 , a second MEMS microphone unit 20 and an ASIC chip 30 , and the sensitivity of the second MEMS microphone unit 20 is greater than Sensitivity of the first MEMS microphone unit 10, the ASIC chip 30 includes a first amplifier 31 electrically connected to the first MEMS microphone unit 10, and a first analog-to-digital converter electrically connected to the first amplifier 31 32. A second amplifier 33 electrically connected to the second MEMS microphone unit 20, a second analog-to-digital converter 34 electrically connected to the second amplifier 33, and a second analog-to-digital converter 34 electrically connected to the first analog-to-digital converter 32 and the The output terminal 35 to which the second analog-to-digital converter 34 is electrically connected.

In this embodiment, the first MEMS microphone unit 10 is a low-sensitivity microphone sensor, and the converted electrical signal is a low-sensitivity electrical signal; the second MEMS microphone unit 20 is a high-sensitivity microphone sensor, and the converted electrical signal is a high-sensitivity electrical signal; the first amplifier 31 amplifies the low-sensitivity electrical signal, and the second amplifier 33 amplifies the high-sensitivity electrical signal; please refer to FIG. 3 , the first analog-to-digital converter 32 converts the low-sensitivity electrical signal into As a digital signal, the second analog-to-digital converter 34 converts the high-sensitivity electrical signal into a digital signal, and the digital signal output by the first analog-to-digital converter 32 and the digital signal output by the second analog-to-digital converter 34 are high-order and low-order respectively. Transmission on the same data line, high AOP and high signal-to-noise ratio are achieved at the same time.

In a first optional implementation manner, the first MEMS microphone unit 10 is a first MEMS chip, and the second MEMS microphone unit 20 is a second MEMS chip. Further, the first MEMS chip and the second MEMS chip can use the same MEMS chip, and the sensitivity of the first MEMS chip and the second MEMS chip can be adjusted by providing different bias voltages to the first MEMS chip and the second MEMS chip respectively. adjust. Therefore, please refer to FIG. 2 , in this embodiment, the ASIC chip 30 further includes a first bias voltage module 36 for providing a bias voltage for the first MEMS chip and a first bias voltage module 36 for the second MEMS chip The chip provides the second bias voltage module 37 of the bias voltage.

In a second optional implementation manner, the first MEMS microphone unit 10 includes a first diaphragm, and the second MEMS microphone unit 20 includes a second diaphragm, wherein the first diaphragm and the second diaphragm The structure and size are different, so that the sensitivity of the first MEMS microphone unit 10 and the second MEMS microphone unit 20 are different, and the first MEMS microphone unit 10 and the second MEMS microphone unit 20 can be integrated in the same on a MEMS chip.

Please continue to refer to FIG. 1 , the input end 11 of the first MEMS microphone unit 10 and the input end 21 of the second MEMS microphone unit 20 are connected to each other and both are grounded. The first input end 311 of the first amplifier 31 is connected to the output end 12 of the first MEMS microphone unit 10 , the second input end 312 of the first amplifier 31 is grounded; The input end 331 is connected to the output end 22 of the second MEMS microphone unit 20 , and the second input end 332 of the second amplifier 33 is grounded. The input end 321 of the first analog-to-digital converter 32 is connected to the output end 313 of the first amplifier 31, the input end 341 of the second analog-to-digital converter 34 is connected to the output end 333 of the second amplifier 33, and the first The output terminal 322 of the analog-to-digital converter 32 and the output terminal 342 of the second analog-to-digital converter 34 are both connected to the output terminal 35 of the ASIC chip 30 .

Second Embodiment

An embodiment of the present application provides a working control method for a MEMS microphone, which is applied to the MEMS microphone of the first embodiment. Please refer to FIG. 4 . The working control method includes the following steps:

S101, the first MEMS microphone unit 10 and the second MEMS microphone unit 20 respectively convert the sound signal input to the MEMS microphone into a first electrical signal and a second electrical signal, wherein the sensitivity of the second electrical signal is greater than that of all the the sensitivity of the first electrical signal.

S102, the first analog-to-digital converter 33 converts the first electrical signal processed by the first amplifier 31 into a first digital signal, and the second analog-to-digital converter 34 converts the second electrical signal processed by the second amplifier 32 into a first digital signal Two digital signals, wherein the first analog-to-digital converter 33 works with a first clock signal, the second analog-to-digital converter 34 works with a second clock signal, the first clock signal and the first clock signal The two clock signals have the same period and are phase delayed by one or more of the periods.

S103, the first digital signal and the second digital signal are superimposed and output.

In step S101, the first MEMS microphone unit 10 and the second MEMS microphone unit 20 respectively process the same sound signal to obtain a first electrical signal and a second electrical signal. In step S102, one of the first analog-to-digital converter 33 and the second analog-to-digital converter 34 can be delayed by several clock cycles from the other, for example, the phase of the first clock signal is delayed by one or more than the second clock signal. Multiple cycles, alternatively, the phase of the second clock signal is delayed by one or more cycles from the first clock signal. In step S103 , the first digital signal is written into the high bit, the second digital signal is written into the low bit, and the two digital signals are superimposed and output by the output terminal 35 .

In this embodiment, when the sound is small, the low-sensitivity first electrical signal is very small, the first digital signal converted by the first analog-to-digital converter 33 is written into high bits, and the high-bit data remains 0; The second digital signal obtained by converting the two electrical signals through the second analog-to-digital converter 34 is written into the low bit. When the sound is louder, the first digital signal converted from the high-sensitivity second electrical signal reaches the full scale, and the second digital signal converted from the low-sensitivity first electrical signal is written to a high bit.

Specifically, in a typical working mode, high-bit data is 8 bits, low-bit data is 16 bits, the sensitivity of the first MEMS microphone unit 10 is -68dBFS, and the sensitivity of the second MEMS microphone unit 20 is -20dBFS. For a 16-bit digital signal, the maximum value is 65536, and the formula for calculating the Decibels Full Scale (dBFS) is

The sample ranges from 1 to 65536, so the dynamic range of the second digital signal is -96dBFS to 0dBFS. Similarly, it can be obtained that the dynamic range of the first digital signal is -48dBFS˜0dBFS. Therefore, the dynamic range of the superimposed signal of the first digital signal and the second digital signal is -144dBFS˜0dBFS. The sound pressure of the superimposed signal of the first digital signal and the second digital signal is 18 dBSPL to 162 dBSPL.

The above are only the embodiments of the present application. It should be pointed out that for those of ordinary skill in the art, improvements can be made without departing from the creative concept of the present application, but these belong to the present application. scope of protection.

Claims

A MEMS microphone, comprising a first MEMS microphone unit, a second MEMS microphone unit and an ASIC chip, the sensitivity of the second MEMS microphone unit is greater than the sensitivity of the first MEMS microphone unit, and the ASIC chip includes A first amplifier electrically connected to the first MEMS microphone unit, a first analog-to-digital converter electrically connected to the first amplifier, a second amplifier electrically connected to the second MEMS microphone unit, and the first amplifier Two amplifiers are electrically connected to a second analog-to-digital converter and an output terminal that is electrically connected to the first analog-to-digital converter and the second analog-to-digital converter, respectively.
The MEMS microphone according to claim 1, wherein the first MEMS microphone unit is a first MEMS chip, and the second MEMS microphone unit is a second MEMS chip.
The MEMS microphone of claim 2, wherein the ASIC chip further comprises a first bias voltage module for providing a bias voltage for the first MEMS chip and a bias voltage module for providing a bias voltage for the second MEMS chip A second bias voltage module for setting the voltage.
The MEMS microphone according to claim 1, wherein the first MEMS microphone unit includes a first diaphragm, the second MEMS microphone unit includes a second diaphragm, the first MEMS microphone unit and the The second MEMS microphone unit is integrated on the third MEMS chip.
The MEMS microphone of claim 1, wherein the input end of the first MEMS microphone unit and the input end of the second MEMS microphone unit are connected to each other and are both grounded.
The MEMS microphone according to claim 5, wherein the first input end of the first amplifier is connected to the output end of the first MEMS microphone unit, and the second input end of the first amplifier is grounded; the The first input end of the second amplifier is connected to the output end of the second MEMS microphone unit, and the second input end of the second amplifier is grounded.
A work control method for a MEMS microphone, wherein the MEMS microphone is the MEMS microphone according to any one of claims 1 to 6, characterized in that, comprising:

The first MEMS microphone unit and the second MEMS microphone unit respectively convert the sound signal input to the MEMS microphone into a first electrical signal and a second electrical signal, wherein the sensitivity of the second electrical signal is greater than that of the first electrical signal. the sensitivity of the signal;

The first analog-to-digital converter converts the first electrical signal processed by the first amplifier into a first digital signal, and the second analog-to-digital converter converts the second electrical signal processed by the second amplifier into a second digital signal, wherein, The first analog-to-digital converter operates with a first clock signal, the second analog-to-digital converter operates with a second clock signal, and the first clock signal and the second clock signal have the same period and are delayed in phase one or more of said cycles;

The first digital signal and the second digital signal are superimposed and output.
The operation control method of the MEMS microphone according to claim 7, wherein the first digital signal is located in a high-order range, and the second digital signal is located in a low-order range.
The operation control method of a MEMS microphone according to claim 8, wherein the sensitivity of the first MEMS microphone unit is -68dBFS, the sensitivity of the second MEMS microphone unit is -20dBFS, and the first digital signal The dynamic range of the superimposed signal with the second digital signal is -144dBFS˜0dBFS.
The operation control method of the MEMS microphone according to claim 9, wherein the sound pressure of the superimposed signal of the first digital signal and the second digital signal is 18 dBSPL to 162 dBSPL.