CN105764017A - Silicon capacitance microphone - Google Patents

Abstract

The invention provides a silicon capacitance microphone. A sensitive structure is cooperated with a frequency characteristic curve of a matched integrated circuit. A response of the sensitive structure of an assigned frequency point in a microphone work bandwidth of a packaging shell is more than 3dB higher than a response of a microphone low-frequency straight segment. The above state can be realized through arranging a size and a material parameter of the sensitive structure. A response of the matched integrated circuit in a frequency range nearby a silicon capacitance microphone work bandwidth is arranged correspondingly so as to guarantee smoothness of the microphone frequency characteristic curve in the work bandwidth. The above state can be realized through adjusting a frequency characteristic of a signal amplification and processing link of the matched integrated circuit. Under an existing technology level, by using design means in the invention, a signal to noise ratio of the silicon capacitance microphone can be increased by more than 1dB.

Description

A kind of silicon capacitor microphone

Technical field

The present invention relates to a kind of silicon capacitor microphone, particularly a kind of silicon capacitor microphone obtaining more excellent signal to noise ratio by adjusting the frequency characteristic of sensitive structure and supporting integrated circuit.

Background technology

Micro electronmechanical (MEMS, Micro-Electro-MechanicalSystem) mike or claim silicon capacitor microphone because its volume is little, be suitable to the advantages such as surface mount and be widely used in the sound collection of tablet electronic device, for instance: mobile phone, MP3, recording pen and monitoring equipment etc..Usually, MEMS system is comprising the sensitive structure of the micromechanics that other physical signallings are converted into the signal of telecommunication foremost, or in the end end comprises the micro mechanical structure executor converting electrical signals to other physical signallings.The sensitive structure of micromechanics plays the translation interface effect of the signal of telecommunication and other physical signallings in MEMS system.The material and cultural needs growing for meeting the people, the index such as the volume of MEMS system, cost, sensitivity, linearity also optimizes raising constantly.In relevant optimisation technique scheme, it is no lack of numerous effort, the progress of manufacturing process is constantly converted into the raising to silicon capacitor microphone signal to noise ratio.Application due to high s/n ratio mike, significant progress has been had at present in fields such as far-field acoustic, speech recognition, echo cancellor, active noise reduction, but then under prior art means, the property indices of silicon capacitor microphone beyond tradition mike, therefore some unprecedented technical problems are also emerged so that the difficulty of the signal to noise ratio improving silicon capacitor microphone further is more and more higher.

On the other hand, for the frequency characteristic in microphone works bandwidth, the frequency response that general application scenario is required in microphone works bandwidth is relatively flat；Otherwise, mike collects the tone color of acoustical signal and also can deform to some extent in corresponding uneven frequency range, thus affecting overall sense of hearing.

For ensureing low cost and the miniaturization feature of silicon capacitor microphone, generally in the industry special IC chip and sensitive structure are supported the use.For operation principle, integrated circuit is close but incomplete same with traditional circuit.For existing integrated circuit level, its bandwidth is very easy to be made wide to ensure the planarization that inband signaling transmits, its frequency characteristic is very smooth in microphone works frequency band, and in fact this is also modal circuit implementations under prior art level.Simultaneously, when the links such as integrated circuit increase filtering are controlled its frequency characteristic, bigger technical difficulty will be run into: the electric capacity as analog circuit filtering is needed can increase cost even affects encapsulation characteristic, and need digital circuit increase special filtering link and develop special filtering algorithm.Therefore for ensureing that integrated circuit coordinates the versatility of various sensitive structures, only need to its frequency characteristic be set to smooth in microphone works frequency band.

Therefore, at traditional silicon capacitor microphone, not by sensitive structure and coordinating that the frequency characteristic curve of supporting integrated circuit is fixed, but respectively respective frequency characteristic is set to smooth in bandwidth, to meet the requirement smooth in bandwidth of frequency characteristic of mike entirety output.Such as Chinese patent CN201509310U and Chinese patent CN203301696U, when being subject to structural parameters restriction when arranging sensitive structure frequency characteristic curve, by arrange the mode of encapsulating structure make the frequency characteristic of its sensitive structure in bandwidth of operation smooth, thus ensure that when the integrated circuit smooth in bandwidth of operation with frequency characteristic mates, smooth in bandwidth of operation of final silicon capacitor microphone frequency characteristic.Although this kind of conventional solution mates versatility by abandoning sensitive structure with encapsulating structure, by encapsulating structure being mated the change of sensitive structure, make mike frequency characteristic reach requirement smooth in bandwidth of operation, but also lose the space improving mike signal to noise ratio further.

Summary of the invention

The invention provides the silicon capacitor microphone that the frequency characteristic of a kind of sensitive structure and supporting integrated circuit is mutually matched, can by being respectively provided with the frequency characteristic of sensitive structure and supporting integrated circuit and making it be mutually matched, ensureing that silicon capacitor microphone frequency characteristic meets under the premise that application requires, under original process conditions limit, improving its signal to noise ratio further.

For solving the problems referred to above, the technical solution used in the present invention is:

A kind of silicon capacitor microphone, its sensitive structure matches with the frequency characteristic of supporting integrated circuit, described sensitive structure specifies high more than the 3dB of response of the response ratio mike low frequency flat segments of frequency in encapsulating housing in microphone works bandwidth, and the response that described supporting integrated circuit is near this frequency is also made and mated setting accordingly.The frequency characteristic of sensitive structure with supporting integrated circuit is made and mates setting, after being to ensure that both mate work, smooth in bandwidth of operation of the frequency characteristic of silicon capacitor microphone itself.And frequency response will be specified in its bandwidth of operation to be set to higher, when being because so doing the reducing effect of silicon capacitor microphone noise is best, sensitive structure frequency characteristic curvilinear integral value after normalization according to the technological limits of each parameter, should be to the maximum principle with microphone noise in working band and determines by this appointment frequency.And the response being assigned frequency is set to 3dB more than higher than the response of low frequency flat segments, it is because such guarantee and makes more than silicon capacitor microphone noise reduction 1dB.

Preferred silicon capacitor microphone, wherein said sensitive structure specifies high more than the 3dB of response of the response ratio mike low frequency flat segments of frequency in encapsulating housing in microphone works bandwidth, realizes by arranging described sensitive structure size in encapsulating housing and material parameter.Although sensitive structure frequency characteristic in encapsulating housing can also be adjusted by arranging encapsulating structure size and dimension, but the versatility abandoning sensitive structure and encapsulating housing for this has adverse effect: encapsulating housing is owing to occurring directly in application scenario, its interface (such as sound inlet) with application scenario, if be modified, certainly will have influence on the range of application of encapsulating housing.

Preferred silicon capacitor microphone, wherein said supporting integrated circuit specifies the response of frequency also to make to mate setting accordingly in microphone works bandwidth, and the frequency characteristic amplified with processing links by adjusting the signal of supporting integrated circuit realizes.In the inventive solutions, the capacitance change signal that sensitive structure produces after being subject to acoustical signal excitation, and after being input to integrated circuit, first capacitance change signal can be converted to voltage change signal by integrated circuit, then by amplification and processing links, voltage signal can be processed.Due to the reason of the relatively more convenient process of electrical signal, the frequency characteristic adjusting supporting integrated circuit can be realized by the frequency characteristic that adjustment is amplified with processing links.In traditional integrated circuit technique scheme, owing to realizing the difficulty of corresponding function in integrated circuits and ensureing this smooth reason that need not additionally filter of frequency characteristic in working band of integrated circuit, pooling feature or full frequency band indifference enlarging function is only had with processing links amplifying, even some scheme is absent from amplification and the processing links of signal, directly exports after being converted to voltage signal.

Preferred silicon capacitor microphone, the wherein said signal adjusting supporting integrated circuit amplifies the frequency characteristic with processing links, realizes by amplifying and increase in processing links a wave filter link at the signal of circuit.If the common wave filter such as low pass filter, band elimination filter, digital filter (mainly including limit impact response filter FIR and infinite impulse response filter IIR) are the modes of the more convenient realization of prior art means, and although the technical scheme such as multiplier, modem can also adjust the frequency characteristic of circuit, but complex owing to implementing, not as the first-selection of technical scheme.

Preferred silicon capacitor microphone, wherein said wave filter, realized by digital circuit means.For Analogous Integrated Electronic Circuits, realize filter function and need that the electric capacity used is extremely difficult to be realized and costly in Analogous Integrated Electronic Circuits, if increasing electric capacity in encapsulating structure, corresponding material cost, process costs and checking cost can be increased, and the increase of components and parts can bring the change of package cavity shape and volume in encapsulating structure, frequency characteristic when sensitive structure is worked wherein can impact again itself.Therefore Analogous Integrated Electronic Circuits realizes that wave filter is complex and cost is also higher.And for digital circuit, the problem being not only absent from filter capacitor, more by various modern filtering methods, filter effect can be optimized；In addition same money digital circuit mates the parameter fluctuation of same batch of multiple sensitive structures also by methods such as auto-adaptive parameters.

The proposition of the present invention so that under existing technological level, the signal to noise ratio of silicon capacitor microphone, owing to applying the design means of the present invention, is improved the signal to noise ratio of more than 1dB mike, adds the market competitiveness of silicon capacitor microphone.Although technical scheme is ensure that mike frequency characteristic abandons the versatility that silicon capacitor microphone sensitive structure is mutually matched with supporting integrated circuit in addition, but by the configuration of respective to sensitive structure and integrated circuit frequency characteristic complex optimum is obtained the technique effect improveing mike signal to noise ratio further.Compare conventional solution, owing to the unit cost of integrated circuit is lower than encapsulating structure, the scheme comparing other ensures mike frequency characteristic by abandoning the matching of sensitive structure and encapsulating structure, technical scheme is applicable to the encapsulating structure of sizes, and the scope of application is wider.

Accompanying drawing explanation

Fig. 1 is each link frequency characteristic and the match condition schematic diagram thereof of traditional silicon capacitance microphone；

Fig. 2 is the sensitive structure of one embodiment of the invention and the scheme schematic diagram of supporting integrated channel frequency characteristic curve coupling；

Fig. 3 is the control system performance schematic diagram of each link signal transmission of the preferred embodiment of the present invention；

Fig. 4 is the Analysis of Noise Properties schematic diagram in each link signal transmission of the preferred embodiment of the present invention；

Three kinds that Fig. 5 is the prestage frequency characteristic of the preferred embodiment of the present invention select example schematic diagram；

Fig. 6 is the prestage of another embodiment of the present invention and the scheme schematic diagram of back-end circuit frequency characteristic coupling.

Detailed description of the invention

Present invention is mainly used for a kind of silicon capacitor microphone obtaining more excellent signal to noise ratio by adjusting the frequency characteristic of sensitive structure and supporting integrated circuit, can under the premise keeping the original outward appearance of silicon capacitor microphone, package dimension and subsequent technique implementation, by abandoning the versatility of sensitive structure and supporting integrated Circuit Matching, silicon capacitor microphone signal to noise ratio under original process conditions limit is improved further, and below in conjunction with concrete drawings and Examples, the invention will be further described.

As it is shown in figure 1, in traditional silicon capacitor microphone scheme, for ensureing sensitive structure and the respective versatility of supporting integrated circuit, generally respectively its frequency characteristic is set to more smooth in bandwidth of operation, and fits together use.Signal is at the mechanics link T through sensitive structure₁After be converted into motor message, again through the T of sensitive structure itself₂Link is converted into electrical signal, and by IC capacitor-voltage conversion links T₃Electrical signal is converted into voltage signal.In traditional integrated circuit technique scheme, owing to realizing the difficulty of corresponding function in integrated circuits and ensureing this smooth reason that need not additionally filter of frequency characteristic in working band of integrated circuit, amplifying and processing links T₄Only have pooling feature or full frequency band indifference enlarging function (with always straight T₂Link is similar), even some scheme is absent from amplification and the processing links T of signal₄, directly export after being converted to voltage signal.

As shown in Figure 2, the technical scheme that the present invention proposes is high more than the 3dB of response of the response ratio mike low frequency flat segments that sensitive structure is specified frequency in encapsulating housing in microphone works bandwidth, and the response that described supporting integrated circuit is near identical frequency is also made and mated setting accordingly.So the frequency characteristic of sensitive structure with supporting integrated circuit is made and mate setting, after not only ensure that both mate work, smooth in bandwidth of operation of the frequency response of silicon capacitor microphone itself, more makes silicon capacitor microphone because of that improve the technique effect of overall more than signal to noise ratio 1dB.Wherein sound inlet 100, sensitive structure 200, encapsulating structure inner chamber 300 has together decided on sensitive structure in silicon capacitor microphone system and has been operated in the frequency characteristic within encapsulating structure, also constitutes the acoustic signals mechanics link 001 to sensitive structure diaphragm displacement signal；The displacement signal of its diaphragm is converted into its capacitance change signal by sensitive structure 200, and constitutes electricity link 002 together with integrated circuit 400, and capacitance change signal is converted into voltage signal by electricity link 002, and final output characterizes the voltage signal of acoustic signals.

Fig. 3, Fig. 4 and Fig. 5 are a preferred embodiment of the present invention.Acoustic signals shows as the changes delta p of the sound intensity in space, by being converted into power Δ F after the diaphragm of the sensitive structure 200 that effective area is A；And sensitive structure shows as quality m on mechanics, stiffness K, damped coefficient is the mass-spring-damper system of b, and its transmission function is:

$T_1\left(s\right)=\frac{1}{{\mathrm{ms}}^2+\mathrm{bs}+K}$

Power Δ F signal after by this system is converted into the displacement signal Δ x of diaphragm, and the displacement signal Δ x of diaphragm is converted to capacitance change signal Δ C further through sensitive structure itself, if at sensitive structure electric capacity C₀Two ends apply fixing voltage drop Δ U, then capacitance change signal Δ C can be exchanged into change in electrical charge signal delta Q=Δ U Δ C, and under the standard sound intensity evaluated when investigating signal to noise ratio, this displacement signal Δ x is relative to sensitive structure natural capacity gap d₀Being an a small amount of, it is believed that the conversion approximately linear of this displacement signal Δ x to charge signal Δ Q, its scale factor is:

T₂(s)=C₀·ΔU/d₀

This link is that sensitive structure determines as the feature of sensor own, and it is in the frequency range paid close attention to and within the scope of the sound intensity of mensuration signal to noise ratio, and amplification is always smooth.

As it is shown on figure 3, change in electrical charge Δ Q signal is at resistance (R)-inductance (L)-electric capacity (C of capacitance-voltage conversion links one similar mass-spring-damper system of entrance of integrated circuit₀) system (RLC system), be converted to voltage signal Δ V through this system.Its transmission function is as follows:

$T_3\left(s\right)=\frac{1}{{\mathrm{Ls}}^2+\mathrm{Rs}+\frac{1}{C_0}}$

In the specific implementation, owing to have employed the element such as audion, field effect transistor in integrated circuit, its transfer function model is also than T for this link₃S () is more complicated, it is impossible to simply by the RLC system description of the present embodiment, but principle is close with it.

Additionally, in the present embodiment, the frequency characteristic of voltage signal Δ V not necessarily meets the requirement planarized in the bandwidth of operation of the frequency characteristic of silicon capacitor microphone again, therefore needs to amplify and processing links T then through the signal of integrated circuit₄The Filtering Processing of (s), last output services frequency band 0～ω₀Interior smooth voltage signal Δ V_out。

Noise in lower surface analysis signals transmission.From energy system, energy is from the electric energy that the changes mechanical energy that " power-displacement " is corresponding is that " charge-voltage " is corresponding, and this is also the sensitive structure reason also known as " transducer ".Energy loss in its energy transfer process is mainly by mechanical damping and what dissipation of energy was caused by electrical damping, the loss of this portion of energy corresponds to the interior of corresponding molecular thermalmotion can be increased, so being white noise in the frequency band paid close attention to, the noise of mechanics link 001 and electricity link 002 is respectivelyWithAnd the unit Shi Li noise unit of the former correspondenceUnit corresponding to the latter is voltage noise unitWherein k_BBeing Boltzmann constant, T is thermodynamic temperature during silicon capacitor microphone work.Additionally, at sensitive structure electric capacity C₀Two ends apply fixing voltage drop Δ U, thus capacitance change signal Δ C is converted to change in electrical charge signal delta Q=Δ U Δ C, this part thing itself can introduce fixed voltage and drop the noise N of Δ U_U, this voltage noise is also white noise in the frequency band paid close attention to, and unit is alsoCan be added to electrical noise

The capacitance-voltage conversion links of sensitive structure 200 itself and integrated circuit 400, constitutes the prestage of circuit, also determines the noise of silicon capacitor microphone.In the present embodiment, prestage transmission function is S (s)=T₁(s)·T₂(s)·T₃S (), the signal eventually passing through integrated circuit 400 amplifies and processing links T₄After (s), ultimately form silicon capacitor microphone Input output Relationship IO (s) of planarization response in bandwidth of operation.And signal amplifies and processing links T₄S (), owing to being not belonging to prestage link, the noise of its correspondence is negligible in the present embodiment.

When weighing signal to noise ratio, generally from the working band 0～ω of silicon capacitor microphone₀One Frequency point ω of interior flat place_cThe sound intensity signal delta P of input normal intensity, test obtains signal intensity IO (ω_c) Δ P A, and to working band 0～ω₀Interior noise is integrated, and weighs its aggregate noise level (allow some weightings acoustically to process, but do not affect the technical scheme of the present embodiment), using ratio between two as the signal to noise ratio of silicon capacitor microphone.Therefore according to can the derive silicon capacitor microphone signal to noise ratio snr of the present embodiment of this model be:

$\mathrm{SNR}=\frac{\mathrm{IO}\left({\mathrm{\ω}}_C\right)\·\mathrm{\ΔP}\·A}{{\∫}_0^{{\mathrm{\ω}}_0}\mathrm{IO}\left(\mathrm{\ω}\right)\·\sqrt{{N_F}^2+\frac{{N_V}^2+{N_U}^2}{S{\left(\mathrm{\ω}\right)}^2}\mathrm{d\ω}}}$

In this formula, at working band 0～ω₀In it is believed that IO (ω)=IO (ω_c), it being consistent with the constant of industry standard, Δ P is the sound intensity signal of normal intensity in the industry, and A is the effective diaphragm area of sensitive structure 200, is also believed to constant after fixing, and three kinds of working band 0～ω₀Interior white noise N_F,N_V,N_U, all respectively have its own the physics limit under technological parameter restriction.So under the premise that other parameters are fixed, adjusting prestage transmission function S (s) and make it at working band 0～ω₀Interior frequency range response is higher, is useful for improving signal to noise ratio snr.

Owing to integrated circuit 400 generally can adopt the element such as audion, field effect transistor, its circuit noise N_V、N_UIt is not necessarily white noise again in bandwidth of operation, and is likely to also comprise the coloured noise composition such as pink noise (1/f noise), brown noise (Brownian noise).Therefore, before being embodied as, can according to concrete circuit noise N_V、N_UActual distribution situation in band, in bandwidth of operation similar to Figure 5, the response of certain frequency is higher than in a plurality of frequency characteristic of low-frequency range 3dB, in process conditions allowed band, selection circuit noise is to frequency characteristic maximum after S (ω) integration, parameter according to given encapsulation cavity body structure 300, then the parameter of the sensitive structure 200 of correspondence is set.After determining the design parameter of capacitance-voltage conversion links of integrated circuit 400, the signal that can pass through to adjust integrated circuit 400 amplifies and processing links T₄S (), ultimately forms silicon capacitor microphone Input output Relationship IO (s) of planarization response in bandwidth of operation, and IO (s) meets the curve of the smooth and frequency response intensity of relevant criterion in industry in bandwidth of operation.

Aforesaid appointment frequency, it is possible to the technological limits according to each parameter of sensitive structure, is principle with microphone noise in working band to the maximum to the sensitive structure frequency characteristic curvilinear integral value after normalization and determines；Wherein normalization refers to that a same coefficient is all multiplied by the response of each frequency to sensitive structure frequency characteristic curve, make the response of its 1KHz place for 0dB (namely 1 times), thus when the characteristic of more a plurality of frequency characteristic itself, getting rid of the interference that its sensitivity is different.Wherein, technological limits includes a lot of aspect and is improving over time, and different types of concrete technology limit is also different.For example, the A process limit is 0.1 micron, and the B process limit is 0.01 micron, and C technology stress control limit is 100MPa, D technology stress control limit is 10MPa.Dimension limit and the limiting range of stress determine K and m, this after have selected technique it was determined that and b parameter is not only determined by above-mentioned technique, also by technique complete rear film Stress Release displacement determine, and technological limits is not only depended in displacement, additionally depend on concrete version and parameter.Also it is similar about how determining appointment frequency, it is actually the available K of technological limits according to each parameter of above-mentioned sensitive structure, b, the restriction scope of m parameter is specified, the noise that can pass through to calculate within the scope of restriction under each different parameters when being embodied as is to the sensitive structure frequency characteristic curvilinear integral value after normalization, the K that the individual maximum value of choosing is corresponding, b, m parameter.When maximizing is relatively complicated, the parameter that engineering can also select bigger integrated value corresponding is similar to.

In this embodiment, owing to employing silicon capacitor microphone operational frequency bandwidth ω₀Prestage transmission function S (s) that neighbouring frequency characteristic is higher, and amplified and processing links T by the signal of integrated circuit 400₄S () adjusts, finally obtain silicon capacitor microphone Input output Relationship IO (s) of planarization response, improve the signal to noise ratio of silicon capacitor microphone.From technology realizes, prestage transmission function S (s) is at operational frequency bandwidth 0～ω₀It is high that interior appointment frequency responds relatively low-frequency range, it is easier to parameter when working in enclosed construction by arranging sensitive structure realizes, and the frequency characteristic being difficult to the capacitance-voltage conversion links by arranging integrated circuit 400 realizes.Therefore it is believed that the frequency curve method to set up of the present invention approximate is equal to the way of " response of sensitive structure response ratio mike low frequency flat segments of frequency range near microphone works bandwidth in encapsulating housing is high, and described supporting integrated circuit is also made in the response of this frequency range and mated setting accordingly ".And it is such approximate, be conducive to each determining technical scheme when sensitive structure and integrated circuit parameter are arranged, thus clear and definite sensitive structure 200 and the respective parameter interface of integrated circuit 400, make sensitive structure 200 and integrated circuit 400 separate, enhance the versatility respectively as silicon capacitor microphone assembly respectively.Still further aspect, integrated circuit 400 still can keep the electrically and mechanically interface of original silicon capacitor microphone input and output, remain its range of application after have modified the frequency characteristic that signal amplifies with processing links.

The scheme schematic diagram that Fig. 6 is the prestage of another embodiment of the present invention and back-end circuit (signal of integrated circuit 400 amplifies and processing links) frequency characteristic mates.It is that the response of some frequency range in working band is positioned below low-frequency range response, and with processing links, the response relative set of these frequency ranges must be higher than low-frequency range by amplifying at the signal of integrated circuit 400, preferably reduce noise effects to obtain after comprehensively and meet the requirement of industry frequency characteristic.The technique effect optimizing silicon capacitor microphone of such comparative example is likely to be better than the present embodiment in theory, but in being embodied as, although signal amplifies and processing links T₄S () is not belonging to prestage link, but owing to there is the part (this portion link is referred to as differentiation element or differentiation element) responding raising along with frequency increase, correspondingly also can introduce extra noise in integrated circuit 400, therefore need to consider when selecting the technical scheme corresponding with this embodiment.

With another embodiment of technical solution of the present invention contrast, be the another kind of scheme attempted in the process realize the present invention of inventor.Be be modified sound inlet 100 or encapsulating structure inner chamber 300 with by the frequency characteristic of sensitive structure 200 at working band 0～ω₀The technical scheme inside revising smooth.The way of this comparative example, is equal to the parameter such as K, m, b of amendment mechanics link 001, although mechanical ring so can be made to save the frequency characteristic of 001 at working band 0～ω₀Inside become smooth, but its damped coefficient b be modified after owing to being limited by physics limit, will not reduce, even can increase to some extent, this just makes its mechanics noise N_FNot anti-reflection increases, and the frequency response curve of its mechanics link 001 is more flat so that its S (ω) curve is at working band 0～ω₀Inside also being consistent with the smooth of industry standard, electrical noise be there is no inhibitory action by this, therefore the overall noise of silicon capacitor microphone is not improved.Owing to have modified sound inlet 100 or encapsulating structure inner chamber 300 for coupling sensitive structure, it is mutually matched between its sensitive structure and encapsulating structure, lose versatility, and amended sound inlet 100 is owing to relating to the change of the mechanical interface of extraneous input audio signal, reduces the range of application of silicon capacitor microphone.

With technical solution of the present invention contrast another embodiment, be by S (ω) curve in working band full frequency band raise, and integrated circuit 400 signal amplify with processing links T₄(ω) the full frequency band decay satisfactory technical scheme of frequency characteristic to ensure silicon microphone is given in again.This way is worthless, do the raising of reduction and the signal to noise ratio being of value to silicon capacitor microphone noise although it is so, but being subject to pretending more loudly the used time in low-frequency range, the saturated meeting of sensitive structure 200 occurs prematurely, even if the signal at integrated circuit 400 amplifies and processing links T₄(ω) being decayed in, the signal of output is also serious distortion again, and this can make the maximum sound intensity that silicon capacitor microphone may apply to reduce, and reduces the scope of application of silicon capacitor microphone.For the solution of the present invention, increase owing to simply meaning to the frequency range response determined near frequency, can also for this frequency range application AW (Anti-Windup, anti-saturation) some Nonlinear Processing means such as method, the saturated meeting preventing sensitive structure 200 occurs prematurely in this frequency range, do not interfere with other performance indications of silicon capacitor microphone, without the scope of application affecting the silicon capacitor microphone to maximum sound intensity aspect simultaneously.

The above description of this invention is illustrative and not restrictive, and those skilled in the art is understood, and it can be carried out many amendments, change or equivalence, but they fall within protection scope of the present invention within the spirit and scope that claim limits.

Claims (5)

1. a silicon capacitor microphone, including encapsulating housing with the sensitive structure being arranged in described encapsulating housing and the integrated circuit matched with described sensitive structure, it is characterized in that: described sensitive structure matches with the frequency characteristic of described integrated circuit, described sensitive structure specify in silicon capacitor microphone bandwidth of operation in described encapsulating housing frequency response ratio its at high more than the 3dB of response of silicon capacitor microphone low frequency flat segments, and the response that described integrated circuit is near described appointment frequency is also made and is mated setting accordingly, the frequency characteristic with processing links is amplified by adjusting the signal of described integrated circuit, make silicon capacitor microphone frequency response curve planarization in bandwidth of operation.

2. silicon capacitor microphone according to claim 1, it is characterized in that: described sensitive structure specify in silicon capacitor microphone bandwidth of operation in described encapsulating housing frequency response ratio its at high more than the 3dB of response of silicon capacitor microphone low frequency flat segments, transmit function by arranging described sensitive structure dimensional parameters in described encapsulating housing and material parameter with the mechanics adjusting described sensitive structureRealizing, wherein, it is m that described sensitive structure shows as quality on mechanics, and rigidity is K, and damped coefficient is the mass-spring-damper system of b.

3. silicon capacitor microphone according to claim 1, it is characterised in that: the described signal adjusting described integrated circuit amplifies the frequency characteristic with processing links, realizes by amplifying and increase in processing links a wave filter link at the signal of circuit.

4. silicon capacitor microphone according to claim 3, it is characterised in that: described wave filter link is realized by digital circuit means.

5. silicon capacitor microphone according to claim 1, it is characterized in that: described appointment frequency, technological limits according to each parameter of described sensitive structure, is principle with silicon capacitor microphone noise in working band to the maximum to the sensitive structure frequency characteristic curvilinear integral value after normalization and determines.