CN106658303A - Microphone system and amplifying circuit - Google Patents
Microphone system and amplifying circuit Download PDFInfo
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- CN106658303A CN106658303A CN201611093982.9A CN201611093982A CN106658303A CN 106658303 A CN106658303 A CN 106658303A CN 201611093982 A CN201611093982 A CN 201611093982A CN 106658303 A CN106658303 A CN 106658303A
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R3/00—Circuits for transducers, loudspeakers or microphones
- H04R3/04—Circuits for transducers, loudspeakers or microphones for correcting frequency response
- H04R3/06—Circuits for transducers, loudspeakers or microphones for correcting frequency response of electrostatic transducers
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R2430/00—Signal processing covered by H04R, not provided for in its groups
- H04R2430/03—Synergistic effects of band splitting and sub-band processing
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- Engineering & Computer Science (AREA)
- Acoustics & Sound (AREA)
- Signal Processing (AREA)
- Circuit For Audible Band Transducer (AREA)
Abstract
The invention discloses a microphone system and an amplifying circuit. The amplifying circuit comprises a buffer circuit, a conditioning circuit and a driving circuit, wherein the buffer circuit is used for buffering a first voltage signal so as to acquire a second voltage signal; the conditioning circuit is used for receiving the second voltage signal and outputting a third voltage signal; the driving circuit is used for driving the third voltage signal so as to acquire an output voltage signal. The conditioning circuit and the driving circuit form an active filtering structure, or the conditioning circuit independently forms an active filtering structure. Frequency characteristics of the active filtering structure provide supplementation and correction for frequency characteristics of the second voltage signal in a target frequency band, so that the microphone system is enabled to realize noise optimization and frequency response planarization in the target frequency band. Compared with the prior art, the embodiment of the invention further improves the signal to noise ratio of the microphone system while avoiding increase in processing difficulty, and increases the flatness of the system sensitivity in the frequency band. Meanwhile, the microphone system has the advantages of high flexibility and low cost.
Description
Technical field
The present invention relates to microphone field, in particular to microphone system and amplifying circuit.
Background technology
MEMS (Micro-Electro-Mechanical System, MEMS) is one kind in semiconductor manufacturing skill
It is growing up on the basis of art, merged photoetching, burn into film, silicon micromachined, non-silicon micromachined and precision optical machinery processing etc.
Technology and the high-tech electronic mechanical system realized.MEMS system generally comprises one for other physical signallings to be converted to into electricity
The micromechanics sensitive structure of signal and its interlock circuit.The material and cultural needs growing to meet the people, MEMS systems
The indexs such as volume, cost, sensitivity, the linearity of system are also improved in constantly optimization.
MEMS microphone because its small volume, be suitable to surface mount the advantages of be widely used in various electronic installations,
For example：Mobile phone, MP3, recording pen and monitoring equipment etc..The sensitive structure included in current MEMS microphone system is usually electricity
Appearance formula MEMS microphone sensor, the sensitive structure mainly includes thin and resilient acoustic diaphragm and a rigid back of the body
Pole plate, so as to back pole plate, acoustic diaphragm and air-gap therebetween have collectively constituted capacitor, for acoustic signals to be turned
It is changed to electric signal.In MEMS microphone system, because micro-electro-mechanical microphone is directly exported according to the acoustic signals for sensing
Electric signal it is very faint, therefore generally need what amplifying circuit was exported to micro-electro-mechanical microphone in micro-electro-mechanical microphone system
Electric signal is amplified.
The signal to noise ratio of MEMS microphone system is equal to the sensitivity of microphone and the ratio of aggregate system noise.MEMS microphone
The main source of the noise in system is：The noise source of sensitive structure and the noise source of circuit part.
With the popularization of smart mobile phone and smart home, on the one hand, people are to the signal to noise ratio of micro-electro-mechanical microphone system
More and more higher is required, on the other hand, general application scenario is required for the frequency response in microphone works bandwidth more to put down
Smooth, otherwise microphone collects the tone color of acoustic signals and also can deform in corresponding uneven frequency range, causes sound wave to be believed
Fidelity number during electric signal is converted to is affected.In prior art, generally by changing sensitive structure or envelope
The method of the physical parameter of dress to reduce the noise of sensitive structure and improve flatness of the system sensitivity in frequency band, for example
Revision encapsulation back cavity shape and size, change sensitive structure parameter etc..However, due to by package dimension and sensitive structure processing work
Skill is limited, and prior art is when implementing with certain difficulty.For example, as package dimension is less and less, after sensitive structure
The scope that cavity volume can increase is more and more limited；By reducing sensitive structure vibrating diaphragm thickness to change the side of sensitive structure parameter
Method also can bring very big difficulty of processing to MEMS processing factories.
Therefore, expect further to lift the signal to noise ratio of microphone system while avoiding increasing difficulty of processing, and increase
Flatness of the system sensitivity in frequency band.
The content of the invention
The present invention provides a kind of microphone system and amplifying circuit, for further while avoiding increasing difficulty of processing
The signal to noise ratio of microphone system is lifted, and increases flatness of the system sensitivity in frequency band.
To reach above-mentioned purpose, according to the first aspect of the invention, there is provided a kind of amplifying circuit, including：Buffer circuit,
For obtaining second voltage signal to first voltage signal buffering；Modulate circuit, for receiving the second voltage signal and defeated
Go out tertiary voltage signal, and drive circuit, for being driven to tertiary voltage signal output voltage signal is obtained, wherein,
The modulate circuit is collectively forming with the drive circuit or the modulate circuit independently forms active power filtering structure, described to have
Frequency characteristic of the frequency characteristic of source filter structure to second voltage signal in target band provides correction so that the Mike
Wind system realizes noise optimization and frequency response planarization in target band.
Preferably, the active power filtering structure has low-pass characteristic or band-stop response.
Preferably, the modulate circuit collectively forms single order or multistage switch filtering structure with the drive circuit.
Preferably, the modulate circuit includes：Clock module, for exporting non-overlapping the first clock signal and second
Clock signal；First electric capacity and the second electric capacity, first electric capacity respectively has one end to be grounded with second electric capacity；The first of series connection
Switch and second switch, the first switch is controlled by first clock signal and second clock with the second switch
Signal, the first switch is connected with the common port of the second switch with the ungrounded end of first electric capacity, and described first
The not common end of switch receives the second voltage signal, and the not common end of the second switch connects with the non-of the second electric capacity
Ground terminal is connected and provides tertiary voltage signal.
Preferably, the drive circuit includes：Operational amplifier, its positive input terminal receives the tertiary voltage signal, its
Output end provides the output voltage signal；3rd electric capacity, the 4th electric capacity and resistance, the 4th electric capacity is with the resistance simultaneously
Be connected to after connection between the output end of the operational amplifier and negative input end, described 3rd electric capacity one end ground connection, the other end with
The negative input end of the operational amplifier is connected.
Preferably, the modulate circuit includes operational transconductance amplifier, and the modulate circuit is common with the drive circuit
Constitute single order or multistage transconductance capacitor filter structure.
Preferably, the drive circuit includes operational amplifier and multiple passive elements, the operational amplifier it is defeated
Enter end to be connected with the output end of the modulate circuit, the output end of the operational amplifier provides the output voltage signal.
Preferably, the amplifying circuit is realized by integrated circuit.
According to a further aspect in the invention, there is provided a kind of microphone system, including：Encapsulating shell with acoustic aperture and its shape
Into cavity；Sensitive structure in the cavity, for acoustic signals to be converted to into the first voltage signal；Positioned at institute
The voltage control circuit in cavity is stated, for providing bias voltage to the sensitive structure；And in the cavity as
Upper any one described amplifying circuit, for producing the output voltage signal according to the first voltage signal.
Preferably, the voltage control circuit is realized with the amplifying circuit by monolithic integrated optical circuit.
The microphone system provided compared to existing microphone system and its amplifying circuit, the present invention and amplifier circuit
The suppression to high-frequency signal is realized by adding modulate circuit, so as to filtering a part of high-frequency noise, improving signal to noise ratio
While, because the frequency characteristic of modulate circuit is maked corrections to the frequency characteristic of sensitive structure, so that microphone system
The frequency characteristic of system can substantially be realized flat in target band, i.e., microphone system is to receiving not in target band
The sensitivity of the acoustic signals of same frequency is close so that microphone system can be kept away when more acoustic signals are converted to into electric signal
Exempt from output voltage signal and larger amplitude fluctuation occur with the change of frequency of sound wave.Also, compared to prior art, the present invention is carried
For microphone system and amplifying circuit have the advantages that flexible design with low cost.
Description of the drawings
In order to be illustrated more clearly that the embodiment of the present invention or technical scheme of the prior art, below will be to embodiment or existing
The accompanying drawing to be used needed for having technology description is briefly described, it should be apparent that, drawings in the following description are only this
Some embodiments of invention, for those of ordinary skill in the art, on the premise of not paying creative work, can be with
Other accompanying drawings are obtained according to these accompanying drawings.
Fig. 1 shows a kind of schematic block diagram of existing microphone system.
Fig. 2 shows the schematic diagram of the frequency response curve of existing microphone system.
Fig. 3 shows the A weighted noises spectrum schematic diagram of existing microphone system.
Fig. 4 illustrates the schematic block diagram of the microphone system of first embodiment of the invention.
Fig. 5 illustrates the structural representation of the modulate circuit of first embodiment of the invention.
Fig. 6 a illustrate the pass between second voltage signal amplitude value A1 of first embodiment of the invention and acoustic signals frequency
It is schematic diagram.
Fig. 6 b are illustrated between the output voltage signal range value A2 of first embodiment of the invention and acoustic signals frequency values
Relation schematic diagram.
Fig. 7 illustrates a kind of structural representation of alternate embodiment of first embodiment of the invention.
Fig. 8 shows the structural representation of the MEMS microphone system of second embodiment of the invention.
Specific embodiment
The present invention is more fully described hereinafter with reference to accompanying drawing.In various figures, identical element is attached using what is be similar to
Icon is remembered to represent.For the sake of clarity, the various pieces in accompanying drawing are not necessarily to scale.Additionally, may not show in figure
Go out some known parts.
Describe hereinafter many specific details of the present invention, the structure of such as device, material, size, place's science and engineering
Skill and technology, to be more clearly understood that the present invention.But just as the skilled person will understand, can not press
The present invention is realized according to these specific details.
Below, referring to the drawings the present invention is described in detail.
Fig. 1 shows a kind of schematic block diagram of existing microphone system.
As shown in figure 1, the existing microphone system 1000 include sensitive structure 1100, voltage control circuit 1200 and
Amplifying circuit 1300.
Voltage control circuit 1200 provides bias voltage Vbias to sensitive structure 1100.Sensitive structure 1100 is MEMS wheats
Gram wind sensor, its primary structure is a capacitor being made up of vibrating diaphragm, back pole plate and air-gap therebetween, described
Acoustic signals can be converted to first voltage signal Vin by capacitor in the presence of bias voltage Vbias.Amplifying circuit 1300
Enter row buffering to first voltage signal Vin and drive, obtain output voltage signal Vout.
The frequency characteristic of microphone refers to the output relative amplitude of microphone with the distribution of acoustic signals frequency, Ke Yiyong
Frequency response curve representing, for representing the relation between sensitivity and audio frequency.Wherein, the sensitivity of microphone is represented
Acoustic energy is converted into microphone the range value of output voltage produced after voltage, is under the excitation of microphone unit sound pressure
Output voltage and the ratio for being input into acoustic pressure.The bandwidth of microphone refers to that microphone senses the scope of frequency of sound wave.
A weightings (A-Weighted) is a kind of criteria weights curve for audio frequency measurement, for reflecting the response of human ear
Characteristic, its standard is formulated by American Standard Association in the forties in 20th century, for describing human ear for different frequency range sound variation
Sensitivity.
Fig. 2 shows the schematic diagram of the frequency response curve of existing microphone system.Fig. 3 shows existing microphone
The A weighted noises spectrum schematic diagram of system.
As shown in Fig. 2 the frequency response curve of existing microphone system expresses the system is receiving different frequency
Sensitivity S during acoustic signals.Can see that frequency response is bent when the frequency of sound wave of input is in the range of 20Hz to 8kHz
Be close to flat, i.e., the microphone system can generate approximate defeated of range value to line according to the acoustic signals of different frequency in the frequency range
Go out voltage signal, realize stable output；But, when the frequency of sound wave of input is more than 8kHz, due to by sensitive structure 1100
Parameter and encapsulation impact, frequency response curve occurs in that significantly fluctuation, i.e., the microphone system is according in the frequency range
There is obvious difference between the range value of the output voltage obtained by the acoustic signals of different frequency, after this is not only influenced whether
Process of the continuous circuit to output voltage signal, and high-frequency noise can be increased so that signal to noise ratio is reduced.A for example shown in Fig. 3 adds
In power (A-weighted) noise spectrum, because sensitivity of the microphone system to the frequency signal is higher, therefore high band makes an uproar
Sound N is equally substantially amplified, and causes high-frequency noise fairly obvious.Therefore, it is generally desirable to the sensitivity of microphone system is in human ear
(20Hz to 20kHz) is flat in the frequency range of discernible acoustic signals.
It is existing to strengthen flatness, lifting signal to noise ratio of the sensitivity of MEMS microphone system in range of target frequencies
Means include revision encapsulation back cavity geomery and sensitive structure parameter.Add yet with package dimension and sensitive structure
The restriction of work technique, the enforcement of above-mentioned means has certain difficulty.For example, with the reduction of package dimension, back cavity shape is encapsulated
The increase scope of shape can be restricted；Meanwhile, change the sensitive structure parameters such as vibrating diaphragm thickness also can bring very to MEMS processing factories
Big difficulty of processing.
Fig. 4 illustrates the schematic block diagram of the microphone system of first embodiment of the invention.
As shown in figure 4, the microphone system of first embodiment of the invention includes sensitive structure 2100, voltage control circuit
2200 and amplifying circuit 2300.
Voltage control circuit 2200 provides bias voltage Vbias to sensitive structure 2100.Sensitive structure 2100 is MEMS wheats
Gram wind sensor, its structure mainly includes the capacitor being made up of vibrating diaphragm, back pole plate and air-gap therebetween, the electricity
Acoustic signals can be converted to first voltage signal Vin by container in the presence of bias voltage Vbias.Amplifying circuit 2300 pairs
First voltage signal Vin enters row buffering and drives, and obtains output voltage signal Vout.
Voltage control circuit 2200 for example includes reference voltage source (Reference Voltage Source), charge pump
(Charge Pump), for producing stable bias voltage Vbias.Meanwhile, voltage control circuit 2200 can also be electric to amplify
Road 230 provides supply voltage (not shown).
Unlike the prior art, amplifying circuit 2300 not only includes buffer circuit 2310 and drive circuit 2320, also
Including modulate circuit 2330.
Buffer circuit 2310 is, for example, voltage follower, and it has high input impedance and low output impedance such that it is able to will
Isolate with late-class circuit with the front stage circuits of buffer circuit connection, it is to avoid the crosstalk between signal；Simultaneously, it is possible to use buffering electricity
The low characteristic of the output impedance of road 2310 realizes its impedance matching with late-class circuit, so as to making an uproar of reducing that subsequent treatment may bring
Sound, the performance for lifting late-class circuit.
Modulate circuit 2330 collectively forms switch-capacitor filtering structure (Switched Capacitor with drive circuit 2320
Filter, SCF), obtain output voltage amplitude value in target band for carrying out process to the frequency domain of second voltage signal Vin_N
Flat output voltage signal Vout.The output voltage signal Vout exported due to drive circuit 2320 is in target band
Voltage amplitude value tends to flat, therefore the signal to noise ratio of output voltage signal Vout gets a promotion.If necessary, drive circuit 2320 can
With output difference signal.
Fig. 5 illustrates the modulate circuit of first embodiment of the invention and the structural representation of drive circuit.
As shown in figure 5, modulate circuit 2330 and drive circuit 2320 collectively form switch-capacitor filtering structure.
Modulate circuit 2330 includes clock module 2331, switch K1 and K2, electric capacity C1 and electric capacity C2, clock module output
First clock signal clk1 and second clock signal clk2, are respectively used to the conducting of controlling switch K1 and turn off and switch K2's
Conducting and shut-off.Switch K1 is connected with the intermediate node of switch K2 series connection with one end of electric capacity C1, and the other end for switching K1 is received
Second voltage signal Vin_N, the other end for switching K2 is connected with one end of electric capacity C2 and exports tertiary voltage signal Vin_L.Electricity
Hold C1 to be grounded with the other end of electric capacity C2.Switch K1 and switch K2 are for example realized by MOSFET.
Drive circuit 2320 includes operational amplifier OP, electric capacity C3, electric capacity C4 and resistance R1.Electric capacity C4 in parallel and electricity
Resistance R1 is connected between the output end of operational amplifier OP and negative input end, and one end ground connection of electric capacity C3, the other end is put with computing
The negative input end connection of big device OP.The tertiary voltage signal of the output of positive input terminal receiving conditioning circuit 2330 of operational amplifier
Vin_L.The output end of operational amplifier provides output voltage signal Vout.
In above-mentioned modulate circuit 2330 and drive circuit 2320, switch-capacitor filtering configuration example such as realizes low-pass characteristic.
Wherein, the first clock signal clk1 for being provided by clock module 2331 and second clock signal clk2 are not overlapped each other and frequency is
The clock of f, under the control of the first clock signal clk1 and second clock signal clk2, switch K1 and switch K2 is according to frequency f
Constantly it is turned on or off：When switch K1 in the presence of the first clock signal clk1 when turning on, switch K2 disconnects, and electric capacity C1 fills
Electricity arrives second voltage signal Vin_N；When switch K2 in the presence of second clock signal clk2 when turning on, switch K1 disconnects, electricity
Hold C1 to charge to electric capacity C2 so that the positive input terminal of operational amplifier OP reaches the magnitude of voltage of tertiary voltage signal Vin_L, transmission
Total electrical charge be C1 (Vin_L-Vin_N), flow to operational amplifier OP positive input terminal voltage Vin_L average current be I=C1
(Vin_L-Vin_N) * f, according to Ohm's law, it is known that under the control of clock module 2331, switch K1, switch K2 and electric capacity
The equivalent resistance Req=1/ (C1*f) that C1 is formed, so as to realize LPF to second voltage signal Vin_N.
Above-mentioned modulate circuit 2330 can be realized by single chip integrated SCF.
Fig. 6 a illustrate the pass between second voltage signal amplitude value A1 of first embodiment of the invention and acoustic signals frequency
It is schematic diagram, Fig. 6 b are illustrated between the output voltage signal range value A2 of first embodiment of the invention and acoustic signals frequency values
Relation schematic diagram.
By to the frequency response curve in existing microphone system as shown in Figure 2 and transferring function by analysis
It is known that the cut-off frequency of the modulate circuit added on the basis of existing microphone system when first embodiment of the invention
During about 8kHz, as shown in Figure 6 b, modulate circuit 2330 can be on frequency domain to second voltage signal with drive circuit 2320
The high-frequency noise of Vin_N is suppressed so that output voltage signal Vout is substantially realized in the frequency range of 20Hz to 20kHz
It is flat.
It should be noted that in the description of above-mentioned modulate circuit 2330 and drive circuit 2320, switch-capacitor filtering knot
Structure realizes low-pass characteristic.Used as a kind of alternative embodiment, switch-capacitor filtering structure can be special with corresponding band resistance
The wave filter (Bandstop Filters, BSF) of property.Meanwhile, the switch electricity that modulate circuit 2330 is realized with drive circuit 2320
Capacitor filter structure is not limited to the switch-capacitor filtering structure described in above-described embodiment.
To avoid switch-capacitor filtering structure from introducing aliasing noise, can be by appropriate design clock frequency and capacitor's capacity
Realize the compromise between low circuit noise and high s/n ratio on the whole.
Advantage using switch-capacitor filtering structure is：When the timing of clock frequency one, the frequency of switch-capacitor filtering structure
Characteristic depends on the ratio of electric capacity；After circuit structure determines, the characteristic of switch-capacitor filtering structure is only relevant with clock frequency, changes
Becoming clock frequency can change its filtering characteristic；Switch-capacitor filtering structure can directly process analog signal, without as numeral
Wave filter needs like that A/D, D/A to change, and simplifies circuit design, improves the reliability of system；Switch-capacitor filtering structure
It is easy to be connected as multistage filter structure, so as to be easy to adjust the frequency characteristic of modulate circuit.Therefore, switch-capacitor filtering structure
High-order lowpass characteristic or the Frequency Response complementary with the frequency response of MEMS microphone sensor can be easily carried out, with very
High flexibility.
The switch-capacitor filtering structure that employs of above-described embodiment is suppressed to high-frequency signal, so as to filter one
While dividing high-frequency noise, improve signal to noise ratio, due to the switching capacity knot that modulate circuit 2330 and drive circuit 2320 are formed
The frequency characteristic of structure can make corrections to the frequency characteristic of sensitive structure 2100, so as to embodiment of the present invention microphone system
Frequency response curve can realize flat, i.e., the correspondence of microphone system 2000 in range of target frequencies in range of target frequencies
The sensitivity of the different acoustic signals of the frequency that receives is close so that microphone system can more realistically turn acoustic signals
It is changed to electric signal and avoids the occurrence of output voltage signal and larger amplitude fluctuation occur with the change of frequency of sound wave.
Fig. 7 illustrates a kind of structural representation of alternate embodiment of first embodiment of the invention.
As shown in fig. 7, used as a kind of alternative embodiment, drive circuit is comprising operational amplifier OP, by the operation amplifier
The positive output end of device feeds back to the electric capacity C4 of negative input end and feeds back to positive input terminal by the negative output terminal of the operational amplifier
Electric capacity C5, modulate circuit 2330 includes operational transconductance amplifier OTA, and modulate circuit 2330 is collectively forming with drive circuit 2320
Transconductance capacitor filter structure.Wherein, the positive input terminal of the operational transconductance amplifier OTA and negative input end receive respectively described the
The differential signal Vin_N_p and Vin_N_n of two voltage signal Vin_N, the positive output end of the operational transconductance amplifier OTA with it is negative
Output end is connected respectively with the negative input end of the operational amplifier OP in the drive circuit with positive input terminal, the drive circuit
In operational amplifier OP positive output end and negative output terminal provide respectively output signal Vout differential signal Vout_p and
Vout_n.Due to the bandwidth continuously adjustabe of transconductance capacitor filter structure, therefore can obtain smart by the transconductance value to transconductance capacitor
High-precision transmission characteristic is realized in really adjustment, and low in energy consumption due to transconductance capacitor filter structure, therefore by this replacements reality
Applying example can realize the characteristic of LPF or bandreject filtering while with low-power consumption.
It should be noted that the transconductance capacitor filter structure being made up of modulate circuit 2330 and drive circuit 2320 can have
There are low-frequency filter characteristicses or bandreject filtering characteristic, and be not limited to said structure.
Fig. 8 shows the structural representation of the MEMS microphone system of second embodiment of the invention.
As shown in figure 8, MEMS microphone system 2000 includes the cavity 700 of encapsulating shell 400 and its formation and is located at
Sensitive structure 2100, voltage control circuit and the amplifying circuit including active filter structure in cavity 600, wherein the electricity
Pressure control circuit and the amplifying circuit are for example realized by integrated circuit 500.Wherein, position corresponding with sensitive structure on encapsulating shell
Put and there is acoustic aperture 410, for providing sensitive structure the passage of voice signal.The active power filtering structure of the amplifier is, for example,
SCF with low pass or band-stop response or the transconductance capacitor filter structure with low pass or band-stop response, institute
Stating the frequency characteristic of active filter can realize correction to the frequency characteristic of the sensitive structure so that high-frequency noise is pressed down
System, signal to noise ratio get a promotion, and cause microphone system frequency response curve realize in range of target frequencies it is flat.
To sum up, the beneficial effects of the present invention is：Employ active filter to suppress high-frequency signal, so as to
While filtering a part of high-frequency noise, lift signal to noise ratio so that the frequency response curve of microphone system is in target frequency model
Flat, i.e., the spirit of the acoustic signals of different frequency of the microphone system to receiving in range of target frequencies can be realized in enclosing
Sensitivity is close, so as to microphone system can avoid output voltage signal with sound wave frequency when acoustic signals are converted to into electric signal
There is larger amplitude fluctuation in the change of rate, meanwhile, compared to prior art, the present invention has the advantages that easy and low cost.
It should be noted that according to the purposes of microphone system, the target band described in this specification is, for example, human ear
The frequency range of acceptable acoustic signals, about 20Hz to 20kHz, the frequency range of the high-frequency signal in the frequency band can be
8kHz to 20kHz.It is of course also possible to be as desired other frequency models by the set of frequency of target band and high-frequency signal
Enclose.
One of ordinary skill in the art will appreciate that：Accompanying drawing is the schematic diagram of one embodiment, module in accompanying drawing or
Flow process is not necessarily implemented necessary to the present invention.
One of ordinary skill in the art will appreciate that：The module in device in embodiment can be according to embodiment description point
In being distributed in the device of embodiment, it is also possible to carry out respective change and be disposed other than in one or more devices of the present embodiment.On
Stating the module of embodiment can merge into a module, it is also possible to be further split into multiple submodule.
It should be noted that herein, such as first and second or the like relational terms are used merely to a reality
Body or operation make a distinction with another entity or operation, and not necessarily require or imply these entities or deposit between operating
In any this actual relation or order.And, term " including ", "comprising" or its any other variant are intended to
Nonexcludability is included, so that a series of process, method, article or equipment including key elements not only will including those
Element, but also including other key elements being not expressly set out, or also include for this process, method, article or equipment
Intrinsic key element.In the absence of more restrictions, the key element for being limited by sentence "including a ...", it is not excluded that
Also there is other identical element in process, method, article or equipment including the key element.
According to embodiments of the invention as described above, these embodiments do not have all of details of detailed descriptionthe, not yet
It is only described specific embodiment to limit the invention.Obviously, as described above, can make many modifications and variations.This explanation
These embodiments are chosen and specifically described to book, is in order to preferably explain the principle and practical application of the present invention, so that affiliated
Technical field technical staff can be used well using modification of the invention and on the basis of the present invention.The present invention only receives right
The restriction of claim and its four corner and equivalent.
Claims (10)
1. a kind of amplifying circuit, including：
Buffer circuit, for obtaining second voltage signal to first voltage signal buffering；
Modulate circuit, for receiving the second voltage signal and exporting tertiary voltage signal, and
Drive circuit, for being driven to tertiary voltage signal output voltage signal is obtained,
Wherein, the modulate circuit is collectively forming with the drive circuit or the modulate circuit independently forms active power filtering knot
Structure, the frequency characteristic of the frequency characteristic of the active power filtering structure to second voltage signal in target band provides correction, makes
Obtain the microphone system and noise optimization and frequency response planarization are realized in target band.
2. amplifying circuit according to claim 1, wherein, the active power filtering structure has low-pass characteristic or band resistance special
Property.
3. amplifying circuit according to claim 2, wherein, the modulate circuit collectively forms single order with the drive circuit
Or multistage switch filtering structure.
4. amplifying circuit according to claim 3, wherein, the modulate circuit includes：
Clock module, for exporting non-overlapping the first clock signal and second clock signal；
First electric capacity and the second electric capacity, first electric capacity respectively has one end to be grounded with second electric capacity；
The first switch and second switch of series connection, the first switch is controlled by first clock with the second switch
Signal and second clock signal, the ungrounded end of the first switch and the common port of the second switch and first electric capacity
Be connected, the not common end of the first switch receives the second voltage signal, the not common end of the second switch with it is described
The ungrounded end of the second electric capacity is connected and provides tertiary voltage signal.
5. amplifying circuit according to claim 4, wherein, the drive circuit includes：
Operational amplifier, its positive input terminal receives the tertiary voltage signal, and its output end provides the output voltage signal；
3rd electric capacity, the 4th electric capacity and resistance, after the 4th electric capacity and the resistor coupled in parallel operation amplifier is connected to
Between the output end and negative input end of device, described 3rd electric capacity one end ground connection, the negative input of the other end and the operational amplifier
End is connected.
6. amplifying circuit according to claim 2, wherein, the modulate circuit includes operational transconductance amplifier, the tune
Reason circuit collectively forms single order or multistage transconductance capacitor filter structure with the drive circuit.
7. amplifying circuit according to claim 6, wherein, the drive circuit includes operational amplifier and multiple passive
Element, the input of the operational amplifier is connected with the output end of the modulate circuit, the output end of the operational amplifier
The output voltage signal is provided.
8. the arbitrary amplifying circuit according to claim 1 to 7, wherein, the amplifying circuit is realized by integrated circuit.
9. a kind of microphone system, including：
Encapsulating shell with acoustic aperture and its cavity of formation；
Sensitive structure in the cavity, for acoustic signals to be converted to into the first voltage signal；
Voltage control circuit in the cavity, for providing bias voltage to the sensitive structure；And
Any one amplifying circuit as described in claim 1 to 8 in the cavity, for being believed according to the first voltage
Number produce the output voltage signal.
10. microphone system according to claim 9, wherein, the voltage control circuit is with the amplifying circuit by list
Piece integrated circuit is realized.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201611093982.9A CN106658303A (en) | 2016-12-01 | 2016-12-01 | Microphone system and amplifying circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201611093982.9A CN106658303A (en) | 2016-12-01 | 2016-12-01 | Microphone system and amplifying circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN106658303A true CN106658303A (en) | 2017-05-10 |
Family
ID=58813759
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201611093982.9A Pending CN106658303A (en) | 2016-12-01 | 2016-12-01 | Microphone system and amplifying circuit |
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| CN (1) | CN106658303A (en) |
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| CN108768317A (en) * | 2018-08-30 | 2018-11-06 | 孙茂友 | Mems microphone preamplifier |
| CN110277967A (en) * | 2019-06-28 | 2019-09-24 | 瓴盛科技有限公司 | A kind of integrated circuit and the mobile terminal including the integrated circuit |
| CN114222232A (en) * | 2021-12-31 | 2022-03-22 | 杭州士兰微电子股份有限公司 | MEMS system and signal processing circuit |
| CN115604637A (en) * | 2022-12-15 | 2023-01-13 | 苏州敏芯微电子技术股份有限公司（Cn） | MEMS microphone and electronic equipment |
| WO2023201828A1 (en) * | 2022-04-20 | 2023-10-26 | 瑞声声学科技(深圳)有限公司 | Microphone |
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| CN110277967A (en) * | 2019-06-28 | 2019-09-24 | 瓴盛科技有限公司 | A kind of integrated circuit and the mobile terminal including the integrated circuit |
| CN114222232A (en) * | 2021-12-31 | 2022-03-22 | 杭州士兰微电子股份有限公司 | MEMS system and signal processing circuit |
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Effective date of registration: 20180726 Address after: 261000 Fengshan Road, Fangzi District, Weifang, Shandong Province, No. 68 Applicant after: Shandong Gettop Acoustic Co.,Ltd. Address before: 100190 Beijing, Haidian District, Zhongguancun, north two, 13, 44, 118 rooms. Applicant before: Beijing Acuti Microsystems Co., Ltd. |
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Application publication date: 20170510 |