CN207720395U - A kind of MEMS digital microphone signals processing circuit - Google Patents

Abstract

The utility model discloses a kind of MEMS digital microphone signals processing circuits, including digital signal input end, the digital signal input end is electrically connected with auto-gain circuit, the auto-gain circuit output end is electrically connected with frequency shift circuit, and the frequency shift circuit output end is electrically connected with digital signal output end；The auto-gain circuit, for MEMS digital microphone signals to be amplified to suitable amplitude；The frequency shift circuit, for changing the frequency of MEMS digital microphone signals, pass through the setting of auto-gain circuit, frequency shift circuit, not only so that the amplitude of pending signal increases to suitable amplitude, convenient for the later stage to a series of processing operations of pending signal, the noise jamming that pending signal generates in processing procedure has also been effective filtered out simultaneously, the distortion factor of pending signal has been reduced, greatly improves the quality of pending signal.

Description

A kind of MEMS digital microphone signals processing circuit

Technical field

The utility model is related to digital processing field, specially a kind of MEMS digital microphone signals processing circuit.

Background technology

MEMS (Micro Electro Mechanical System) microphone is the microphone manufactured based on MEMS technology, is exactly briefly an electricity Container is integrated on micro- silicon wafer, and Surface Mount technique may be used and manufactured, and can bear very high Reflow Soldering temperature, be easy with CMOS technology and other voicefrequency circuits are integrated, and inhibit energy with improved noise removing performance and good RF and EMI .MEMS whole potential of microphone are also to be excavated, but the product of this technology is used to embody in numerous applications In the application of many advantages, especially middle and high end mobile phone.

The development prospect of MEMS microphone is still than broader, and for large-scale semiconductor maker, they have Prepare the core competence for making the product line.It is MEMS design and manufacturing capacity, followed by ASIC design and manufacturing capacity first, It is finally large capacity, inexpensive encapsulation ability.So far, audio company is always in occupation of almost entire MEMS microphone city , they have to rely on Semiconductor foundries and provide the relevant technologies and participate in the profits with them.Now, entering for Infineon is meaned It the market and has new selection, and reduce the risk of element buyer.

Limitation in terms of size is essentially from MEMS itself.In addition, since audio port cannot use vacuum tool to carry out Operation, further reducing for size will be limited by manufacturing process Plays automation pasting tool.It will assemble in ASIC At more multi-functional：It is the first step with numeral output；Also using standard component, such as wind noise cancellation signal filter assemblies；Special purpose interface and Signal Pretreatment will become prodigious application field；RF shieldings can be also further improved.In terms of audio, MEMS microphone Also many variations are had.SMM310 is not only optimized in the frequency range of 20Hz-20kHz for voice, also higher Acoustics sensibility.

The important module of one of them in MEMS microphone is exactly its internal signal processing circuit, signal processing circuit pair The collected voice signal of MEMS microphone is handled, and is stablized with guarantee, the output of high-fidelity rate.It is in the prior art MEMS digital microphone signal processing circuit types are more, and treated, and effect is also more satisfactory.

But existing MEMS digital microphone signals processing circuit has the following defects：

(1) MEMS digital signal processing circuits in the prior art are not complete to the noise element removal in pending signal Face causes to contain excessive noise, or even phenomenon of uttering long and high-pitched sounds in the sound sent out；

(2) when MEMS digital signal processing circuits in the prior art are amplified pending signal, gain is fixed, and is led It causes amplified pending signal amplitude unstable, active ingredient in pending signal is caused to lose or introduce new noise letter Number.

Invention content

In order to overcome the shortcomings of that prior art, the utility model provide a kind of MEMS digital microphone signals processing electricity It is convenient for a series of processing of the later stage to pending signal not only so that the amplitude of pending signal increases to suitable amplitude in road Operation, while the noise jamming that pending signal generates in processing procedure has also been effective filtered out, reduce pending signal The distortion factor, greatly improve the quality of pending signal, can effectively solve the problem that background technology propose the problem of.

Technical solution adopted by the utility model to solve its technical problems is：

A kind of MEMS digital microphone signals processing circuit, including the digital signal input end, the automatic gain that are linked in sequence Circuit, frequency shift circuit and digital signal output end；The auto-gain circuit, for MEMS digital microphone signals to be amplified to Suitable amplitude；The frequency shift circuit, for changing the frequency of MEMS digital microphone signals.

Further, a kind of MEMS digital microphone signals processing circuit further include the auto-gain circuit with it is described The codan connected between frequency shift circuit further includes described automatic for removing the interference signal after gain in circuit The codan connected between gain circuitry and the frequency shift circuit, for removing the interference signal after gain in circuit.

Further, the codan includes common mode interference suppression module and DM EMI suppression module, described Common mode interference suppression module, for removing the common mode interference after gain in circuit, the DM EMI suppression module, for removing DM EMI after gain in circuit.

Further, it is connected in series between the common mode interference suppression module and DM EMI suppression module.

Further, a kind of MEMS digital microphone signals processing circuit further includes in the frequency shift circuit and the number The filter circuit connected between signal output end, the filter circuit are used to filter out the noise letter generated in signal processing Number.

Compared with prior art, the utility model has the beneficial effects that：

(1) efficient combination that the auto-gain circuit of the utility model is amplified using Linear Amplifer and compression is to pending letter It number is adjusted, when weak signal inputs, linear amplifier circuit work ensures the intensity of output signal；When input signal reaches When some strength, starts compression amplifying circuit, output amplitude is made to reduce, treated, and signal amplitude is stablized, and improves pending The quality of signal；

(2) frequency shift circuit of the utility model is corrected by frequecy characteristic and is adjusted, and frequency characteristic can be made uniform, to reduce Frequency distortion reduces the distortion factor, while can also improve speech articulation, according to interior space difference, adjusts shift frequency number, avoids again Raw reverberation interference, greatly improves speech articulation.

Description of the drawings

Fig. 1 is the utility model signal end circuit diagram；

Fig. 2 is the integrated circuit schematic diagram of the utility model.

Figure label：

1- digital signal input ends；2- auto-gain circuits；3- frequency shift circuits；4- digital signal output ends, 5- interference suppressions Circuit processed；6- filter circuits；

501- common mode interference suppression modules；502- DM EMI suppression modules.

Specific implementation mode

The following will be combined with the drawings in the embodiments of the present invention, carries out the technical scheme in the embodiment of the utility model Clearly and completely describe, it is clear that the described embodiments are only a part of the embodiments of the utility model, rather than whole Embodiment.Based on the embodiments of the present invention, those of ordinary skill in the art are without making creative work The every other embodiment obtained, shall fall within the protection scope of the present invention.

As depicted in figs. 1 and 2, the utility model provides a kind of MEMS digital microphone signals processing circuit, including suitable Digital signal input end 1, auto-gain circuit 2, frequency shift circuit 3 and the digital signal output end 4 of sequence connection, the automatic gain Circuit 2, for MEMS digital microphone signals to be amplified to suitable amplitude, the frequency shift circuit 3, for changing MEMS numbers The frequency of microphone signal.

In present embodiment, digital signal input end 1 is connect with the output end of MEMS digital microphones, is used as pending number The pickup of word signal, auto-gain circuit 2 increase for the amplitude of MEMS digital microphone signals to be amplified to suitable amplitude The too small processing signal amplitude for leading to the later stage of benefit is too small and can not be handled, the excessive introducing for easily causing noise signal of gain, Suitable gain makes the amplitude of pending signal moderate, and processing of the later stage to the signal, auto-gain circuit 2 is convenient for utilize line Property amplification and compression amplification efficient combination pending signal is adjusted, when weak signal inputs, linear amplifier circuit work Make, ensures the intensity of output signal；When input signal reaches some strength, starts compression amplifying circuit, output amplitude is made to drop Low, the setting of auto-gain circuit 2 provides a convenient, frequency shift circuit 3, for changing MEMS for the signal processing work in later stage The frequency of voice signal can be increased 5Hz, destroy the condition for generating acoustic feedback by the frequency of digital microphone signal, frequency shift circuit 3, To inhibit acoustic feedback, frequency shift circuit 3 to correct and adjust by frequecy characteristic, frequency characteristic can be made uniform, to reduce frequency Distortion reduces the distortion factor, while can also improve speech articulation, according to interior space difference, adjusts shift frequency number, avoids regeneration mixed Interference is rung, speech articulation is greatly improved.

Codan 5 is connected between the auto-gain circuit 2 and the frequency shift circuit 3, for removing gain Interference signal in circuit afterwards, the codan 5 include common mode interference suppression module 501 and DM EMI suppression module 502, the common mode interference suppression module 501, for removing the common mode interference after gain in circuit, the DM EMI inhibits mould Block 502, for removing the DM EMI after gain in circuit, the common mode interference suppression module 501 and DM EMI inhibit mould It is connected in series between block 502.

In present embodiment, the interference signal that codan 5 generates when working circuit filters out, automatic gain Circuit 2 is interfered by external environment at work, and it is that interference voltage is being believed to generate common mode interference and DM EMI, common mode interference Amplitude on number line and its loop line is identical, and voltage here is using any one neighbouring object as reference potential, interference electric current circuit Then to be flowed in the circuit that conducting wire is constituted with Reference, DM EMI be interference voltage be present in signal wire and its loop line it Between, interference electric current circuit is flowed in the circuit that conducting wire is constituted with Reference, the introducing of common mode interference and DM EMI, The distortion factor for greatly improving pending signal is unfavorable for the processing in later stage, and common mode interference suppression module 501 and differential mode are dry The setting for disturbing suppression module 502 reduces common mode interference and DM EMI in circuit, improves the quality of pending signal, Common mode interference suppression module 501 can be used gain and be realized for 1 differential amplifier circuit, the common mode suppression of general difference amplifier System more than the higher reachable percentage shellfish of performance, can effectively inhibit the common mode interference in circuit, differential mode than about tens decibels Differential mode choke coil can be used to realize in AF panel module 502, and differential mode choke coil is played a leading role in Differential Mode insertion loss Inductance element seals in differential mode choke coil and is equivalent to the inductance for sealing in differential-mode current generation in circuit, this inductance is equivalent to One low-pass filtering element, to play differential mode inhibiting effect.

It is connected with filter circuit 6 between the frequency shift circuit 3 and the digital signal output end 4, the filter circuit 6, For filtering out the noise signal generated in signal processing.

In present embodiment, filter circuit 6 filters out the noise signal signal in circuit, ensure that processing signal Bandpass filter can be used to realize in quality, in the present embodiment, filter circuit 6, and bandpass filter can only pass through a certain frequency Frequency component within the scope of rate but the filter that the frequency component of other ranges is decayed to extremely low level, according to pending letter Number working frequency determine the upper cut off frequency and lower limiting frequency of bandpass filter, be less than the noise signal quilt of lower limiting frequency It filters out, the noise signal higher than upper cut off frequency is also filtered out, and last only remaining useful processing signal, filter circuit 6 is set Set the quality for greatly improving processing signal.

It is obvious to a person skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and And without departing substantially from the spirit or essential attributes of the utility model, it can realize that this practicality is new in other specific forms Type.Therefore, in all respects, the present embodiments are to be considered as illustrative and not restrictive, this practicality is new The range of type is indicated by the appended claims rather than the foregoing description, it is intended that containing in the equivalent requirements of the claims will be fallen All changes in justice and range are embraced therein.Any reference numeral in claim should not be considered as limitation Involved claim.

Claims (5)

1. a kind of MEMS digital microphone signals processing circuit, including digital signal input end (1), it is characterised in that：The number Word signal input part (1) is electrically connected with auto-gain circuit (2), and auto-gain circuit (2) output end is electrically connected with Frequency shift circuit (3), frequency shift circuit (3) output end are electrically connected with digital signal output end (4)；

The auto-gain circuit (2), for MEMS digital microphone signals to be amplified to suitable amplitude；

The frequency shift circuit (3), for changing the frequency of MEMS digital microphone signals.

2. a kind of MEMS digital microphone signals processing circuit according to claim 1, it is characterised in that：Further include in institute The codan (5) connected between auto-gain circuit (2) and the frequency shift circuit (3) is stated, for removing electricity after gain Interference signal in road.

3. a kind of MEMS digital microphone signals processing circuit according to claim 2, it is characterised in that：The interference suppression Circuit (5) processed includes common mode interference suppression module (501) and DM EMI suppression module (502), and the common mode interference inhibits mould Block (501), for removing the common mode interference after gain in circuit, the DM EMI suppression module (502), for removing gain DM EMI in circuit afterwards.

4. a kind of MEMS digital microphone signals processing circuit according to claim 3, it is characterised in that：The common mode is dry It disturbs and is connected in series between suppression module (501) and DM EMI suppression module (502).

5. a kind of MEMS digital microphone signals processing circuit according to claim 1, it is characterised in that：Further include in institute The filter circuit (6) connected between frequency shift circuit (3) and the digital signal output end (4) is stated, the filter circuit (6) is used for Filter out the noise signal generated in signal processing.