CN203942499U - For high-gain preamplifier and the electret microphone of electret microphone - Google Patents
For high-gain preamplifier and the electret microphone of electret microphone Download PDFInfo
- Publication number
- CN203942499U CN203942499U CN201420243692.8U CN201420243692U CN203942499U CN 203942499 U CN203942499 U CN 203942499U CN 201420243692 U CN201420243692 U CN 201420243692U CN 203942499 U CN203942499 U CN 203942499U
- Authority
- CN
- China
- Prior art keywords
- transistor
- pmos
- preamplifier
- nmos pass
- amplifier
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Abstract
The utility model discloses a kind of electret microphone high-gain preamplifier.This amplifier comprises PMOS transistor, the first and second nmos pass transistors, and current source, wherein the transistorized grid of PMOS is as the input of this amplifier, the drain electrode of described the second nmos pass transistor is as the output of this amplifier, the first end of described current source is connected with the drain electrode of the second nmos pass transistor, the second end is connected with the drain electrode of the transistorized source electrode of described PMOS and the first nmos pass transistor, the grid of described the first and second nmos pass transistors connects, and the source ground of the transistorized drain electrode of described PMOS and the first and second nmos pass transistors.The utility model provides a kind of high-gain, the little preamplifier that can be applied to ECM microphone of volume thus.The utility model also provides a kind of electret microphone that comprises this preamplifier.
Description
Technical field
The utility model relates to microelectronics technology, more properly, belongs to CMOS integrated circuit, and this circuit is as the preamplifier of electret (ECM) microphone in communication system.
Background technology
In speech communication system, mainly still adopt at present electret (ECM) microphone to realize the conversion of voice signal to the signal of telecommunication.Electret (ECM) microphone is two pin devices, one of them pin ground connection, and another pin is for signal output and give chip power supply.ECM microphone composition comprises 3 parts: microphone case, electret capacitor and preamplifier.In microphone case, there is electret capacitor microphone head, junction field effect transistor (JFET) amplifier.Two pin ECM microphones of this employing JFET amplifier are easy to application with it and cost of manufacture is low etc. that feature is used widely in communication system.But along with reducing of portable type electronic product volume, electret capacitor microphone head volume progressively reduces, microphone case diameter is reduced to 30mm by 90mm, and electret capacitor is reduced to 2.0-2.5pF left and right by about 10pF.And the input capacitance size of JFET device is generally at the 10pF order of magnitude, if still adopt junction field effect transistor (JFET) amplifier in electret microphone, will weaken the sensitivity of electret microphone, cause its signal to noise ratio (SNR) variation.Therefore, need high-gain, the preamplifier device of low input capacitance substitutes traditional JFET amplifier.
US Patent No. 6888408B2 has proposed a kind of high-gain preamplifier of manufacturing by CMOS technology, and as shown in Figure 1, this amplifier pin is consistent with JFET device pin, can directly be used for substituting JFET amplifier.This amplifier uses pmos source follower as input, nmos device drains as amplifier out, and comprise two-stage amplifying circuit, first order circuit comprises pmos source follower, voltage amplification factor is less than or approaches 1, second level circuit comprises two nmos devices of common source structure, and voltage gain can do very highly.The grid of PMOS device PM1 is used as the input of amplifier, and its source electrode output is coupled to second circuit by capacitor C1.In the circuit of the second level, nmos device NM2 provides direct current (DC) bias for nmos device NM1.Whole amplifier gain mainly determines by second level circuit, and its output voltage gain can approximate evaluation be the product of NM2 mutual conductance Gm2 and load resistance RL, that is: Gm2*RL.In order to obtain high voltage gain, the size of nmos device NM2 will be done greatly to obtain high mutual conductance Gm2, in order not reduce the gain loss of device from first order amplifier to second level amplifier, coupling capacitor C1 also will do more greatly to reduce its dividing potential drop impact, and it is large that whole like this chip size also will become thereupon.
This amplifier mainly contains following shortcoming:
1) in amplifier, need integrated large capacitor C1, will take very large chip area;
2) amplifier needs the resistor R1 of integrated large resistance, but the resistance of this resistor is very difficult precisely controlled in manufacturing process, is also that the voltage gain of amplifier is difficult to precisely controlled;
3) resistor R1 and capacitor C1 have formed high-pass filtering circuit, such circuit structure is difficult to meet and both required filter circuit low side frequency lower than 50Hz simultaneously, while having requirement amplifier to power on, makes rapidly nmos device NM1 obtain the requirement of stable direct current (DC) bias.
In addition, US Patent No. 6160450 has proposed the another kind of high-gain preamplifier of manufacturing by BiCMOS technology, as shown in Figure 2.The pin of this amplifier is consistent with JFET device pin, can directly be used for substituting JFET amplifier.This amplifier uses PMOS transistor M1 and M2 as differential amplifier input, and Qout is as output for bipolar device NPN transistor.The PMOS transistor M1 that this amplifier main feature is input differential amplifier and M2 adopt dissymmetrical structure, the source series resistor Roffset of transistor M1, the grid of transistor M2 can be biased in the grid voltage higher than M1, the grid of transistor M1 is by diode Dbias ground connection, because not having electric current to pass through, the voltage of this grid is approximately zero volt, transistor M2 grid can be setovered by the upper feedback voltage of output resistance R gain like this, because the multiplication factor of input PMOS amplifier and amplifier B is very high, PMOS amplifier, the feedback loop of amplifier B and bipolar device Qout composition, make the voltage Vgain on resistor Rgain follow change in voltage on input electret capacitor, the upper curent change of load Rload is followed the upper curent change of resistor Rgain, the gain of amplifier voltage is Rload/Rgain like this.The resistance size of reconciling resistor Rgain can obtain different voltage gains.The advantage of this circuit is that voltage gain can fine adjusting control, but has following points deficiency:
1) PMOS differential amplifier and internal amplifier B have increased the noise of chip;
2) PMOS differential amplifier Miller effect causes that input capacitance becomes large;
3) adopt MOS device and bipolar device (BJT), improved manufacturing cost.
4) existence of resistor Roffset has also increased chip noise.
Therefore, need a kind of high-gain, volume little, preferably can be applied to the preamplifier of ECM microphone.
Utility model content
For the deficiency of existing electret (ECM) microphone tradition amplifier JFET and two kinds of amplifiers existence noted earlier, the utility model is intended to propose a kind of new high-gain preamplifier, to meet the high-gain to small-sized electret amplifier, the requirement of small size in present speech communication equipment.
According to an aspect of the present utility model, a kind of electret microphone high-gain preamplifier is provided, this amplifier is made up of two-stage amplifying circuit, wherein first order amplifying circuit uses pmos source follower as input, second level amplifying circuit is to use NMOS commonsource amplifier, and first order amplifying circuit is realized with mirror current source to second level amplifying circuit.
According on the other hand of the present utility model, a kind of electret microphone high-gain preamplifier is provided, this amplifier comprises a PMOS transistor, the first and second nmos pass transistors, and current source,
The transistorized grid of described PMOS is as the input of this amplifier, and the drain electrode of described the second nmos pass transistor is used as the output of this amplifier,
The first end of described current source is connected with the drain electrode of the second nmos pass transistor, and the second end is connected with the drain electrode of the transistorized source electrode of described PMOS and the first nmos pass transistor,
The grid of described the first and second nmos pass transistors connects, and
The source ground of the transistorized drain electrode of described PMOS and the first and second nmos pass transistors.
Preferably, the transistorized grid of PMOS is by resistive device ground connection.For example, this grid can pass through resistor, diode or MOS device constant resistance device ground connection.
Preferably, described current source is realized with the first resistor.
Preferably, described current source is realized with depletion type nmos transistor and the second resistor.
Preferably, the drain electrode of described depletion type nmos transistor is as the first end of described current source, and the source series of described depletion type nmos transistor is connected the second end as described current source after connecting described the second resistor with its grid.
Preferably, described current source is realized in the mode of two PMOS transistors and reference current source.
Preferably, the source electrode of described the first and second nmos pass transistors is respectively by resistor or resistive device ground connection.
Preferably, this preamplifier further comprises the low pass filter between the grid that is coupling in the first and second nmos devices.
Provide a kind of electret microphone more on the one hand according to of the present utility model, comprise electret microphone as above high-gain preamplifier.
According to preamplifier of the present utility model, in the time that the transistorized input voltage of input PMOS changes, the clamping action having due to the structure of the diode form of the first nmos device, the transistorized source voltage of PMOS can be remained unchanged substantially, and the threshold voltage value (Vth) that maintains the first nmos device is upper and lower.Because current source current is constant, so, along with the variation of the PMOS transistor current of flowing through, the corresponding increase or reduce identical quantity thereupon of the electric current of first nmos pass transistor of flowing through.The first and second nmos pass transistors form mirror current source, and the electric current of the second nmos pass transistor is followed in proportion the curent change of the first nmos pass transistor and changed.In the time that the value of the channel width-over-length ratio W/L of the second nmos pass transistor is N times of value of the channel width-over-length ratio W/L of the first nmos pass transistor, the electric current of the second nmos pass transistor be also the first nmos pass transistor electric current N doubly.Thus, the voltage gain Gv of this preamplifier can be derived as:
Gv＝Gpm1*N*RL
Wherein Gpm1 is the mutual conductance of PMOS device, and N is the ratio of the channel width-over-length ratio of the second nmos pass transistor and the channel width-over-length ratio of the first nmos pass transistor, and RL is output load resistance.Set the mutual conductance Gpm1 of PMOS device by design current source electric current and PMOS transistor size, and set the dimensional ratios N of the first and second nmos pass transistors, can obtain the needed high-gain of preamplifier.
The preamplifier that the utility model provides can adopt the manufacture of CMOS ic manufacturing technology, lower than BiCMOS ic manufacturing technology cost.The utility model adopts PMOS transistor as amplifier in, and grid can pass through for example high resistance resistor ground connection, can realize like this preamplifier of low noise and low input capacitance.The output of the utility model preamplifier adopts the common source structure of the first and second nmos pass transistors can further realize its high-gain.Simultaneously, from first order amplifying circuit to second level amplifying circuit, the first and second nmos pass transistors form image current source structure, the curent change of input stage the first nmos pass transistor be reflected to output device second nmos pass transistor identical with the transistorized curent change of PMOS, has avoided in US Patent No. 6888408B2 the amplifier first order to the low frequency capacitive coupling problem of the second level like this.Further, according to preferred embodiment of the present utility model, can filter the noise signal of audio frequency more than 20KHz by forming low pass filter between the current source at the first and second nmos devices formation mirror images, improve circuit output signal-to-noise ratio (SNR).In the time realizing this low pass filter with the form of resistor and capacitor, by by the size design of resistor and capacitor in the reasonable scope, this low pass filter can easily be integrated on chip.
Brief description of the drawings
Below in conjunction with accompanying drawing, embodiment of the present utility model is described in further detail.
Fig. 1 illustrates the ECM preamplifier circuit schematic diagram of one of prior art.
Fig. 2 illustrates the ECM preamplifier circuit schematic diagram of another prior art.
Fig. 3 illustrates according to the ECM of the utility model the first preferred embodiment CMOS preamplifier circuit schematic diagram.
Fig. 4 illustrates according to the ECM of the utility model the second preferred embodiment CMOS preamplifier circuit schematic diagram.
Fig. 5 illustrates that the typical gains of preamplifier shown in Fig. 4 distributes.
Fig. 6 illustrates according to the ECM of the utility model the 3rd embodiment CMOS preamplifier circuit schematic diagram.
Fig. 7 illustrates according to the ECM of the utility model the 4th embodiment CMOS preamplifier circuit schematic diagram.
Fig. 8 illustrates according to the ECM of the utility model the 4th embodiment CMOS preamplifier circuit schematic diagram.
Fig. 9 illustrates according to the ECM of the utility model the 4th embodiment CMOS preamplifier circuit schematic diagram.
Embodiment
In order to be illustrated more clearly in the utility model, below in conjunction with preferred embodiments and drawings, the utility model is described further.Parts similar in accompanying drawing represent with same or analogous Reference numeral.It will be appreciated by those skilled in the art that specifically described content is illustrative and nonrestrictive below, should not limit protection range of the present utility model with this.
Fig. 3 illustrates according to the circuit diagram of the ECM of the utility model the first embodiment CMOS preamplifier 300.Preamplifier 300 comprises the PMOS transistor PM1 as the first order, the first and second nmos pass transistor NM1, NM2 and the current sources that connect as the common source of the second level.The grid of PMOS transistor PM1 is as the input of preamplifier, and with the ECM transducer coupling of electret microphone, the drain electrode of the second nmos pass transistor NM2 is used as the output of preamplifier 300.Supply voltage VDD provides power by load resistance RL for this preamplifier 300 through output.This supply voltage is coupled respectively to grid and the drain electrode of source electrode and the first nmos pass transistor NM1 of PMOS transistor PM1 through current source I1.The grid of described the first and second nmos pass transistors connects, and, the drain electrode of PMOS transistor PM1, the first and second nmos pass transistor NM1, the source ground of NM2.First order PMOS transistor can be configured to pmos source follower, and its gate input, by high resistance device Rb ground connection, to realize low noise and low input capacitance, and is easy to arrange DC bias voltage.As an alternative, the transistorized grid of PMOS can be realized by diode, MOS device or other circuit structures that is equal to resistor.
In the time of the change in voltage of input PMOS device PM1 input, the clamping action having due to the diode-type structure of nmos device NM1, PMOS device PM1 source voltage is remained unchanged substantially, maintain nmos device NM1 threshold voltage value (Vth) upper and lower.Due to current source I1 current constant, along with minimizing or the increase of the PMOS transistor PM1 electric current of flowing through, the corresponding increase or reduce identical quantity thereupon of the electric current of the nmos pass transistor NM1 that flows through.The first and second nmos pass transistor NM1 and NM2 form mirror current source, and transistor NM2 electric current is followed transistor NM1 curent change in proportion.If the channel width-over-length ratio W/L value of nmos pass transistor NM2 be transistor NM1 channel width-over-length ratio W/L value N doubly, transistor NM2 curent change by be transistor NM1 device current N doubly.
When the microphone electret voltage being connected with input is due to sound pressure variations, while causing the input voltage variation of preamplifier, the electric current of transistor PM1 of flowing through also changes, such as increasing Δ I, the corresponding Δ I that reduces of electric current of transistor NM1 so flows through, transistor NM2 electric current also reduces Δ I*N thereupon, and the output end voltage of amplifier is changed to
ΔV＝ΔI*N*RL，
The voltage gain Gv of preamplifier is:
Gv＝ΔI*N*RL/ΔV＝Gpm1*N*RL。
Wherein, Gpm1=Δ I/ Δ V, is the mutual conductance of PMOS device PM1, and therefore, the gain of preamplifier is determined the dimension scale N of NM1 by mutual conductance and the nmos device NM2 of PMOS device PM1.
Set the mutual conductance Gpm1 of PM1 by design current source electric current I 1 and PMOS device PM1 size, and by setting the device size ratio N of NM2 to NM1, can obtain the needed voltage gain of preamplifier.By this way, the size of PMOS transistor PM1 need not be very large, and input capacitance is controlled in 2pF, just can increase the gain of amplifier.
The utility model amplifier adopts pmos source follower as input, PMOS grid can be biased in zero volt, output is nmos transistor drain, and pin is consistent with JFET amplifier, can directly replace JFET amplifier and be used on electret (ECM) microphone.Microphone is also two pin devices, one of them pin ground connection, and another pin is for signal output and give chip power supply.ECM microphone can be used on mobile phone and other voice transfer electronic product.
Fig. 4 illustrates according to the circuit diagram of the ECM of the utility model the second embodiment CMOS preamplifier 400.Be different from the preamplifier 300 shown in Fig. 3, this preamplifier 400 further comprises and is connected to the first and second nmos pass transistor NM1, the first resistor R1 between the grid of NM2 and be connected to the first capacitor C1 between the first resistor and earth potential.
In this preamplifier 400, the grid of first order PMOS transistor PM1 is as input and by the resistor Rb ground connection of a large resistance.The drain and gate of PMOS transistor PM1 source electrode and the first nmos pass transistor NM1 is received current source I1, nmos pass transistor NM1 is diode structure, flow through its curent change when little, and drain-gate pole tension is substantially constant, maintains nmos pass transistor NM1 threshold voltage value (Vth) upper and lower.Like this, in the time that input terminal voltage changes, PMOS transistor PM1 source voltage remains unchanged substantially, and the gate-source voltage Vgs of PMOS transistor PM1 changes, and PMOS is transistorized to change by electric current.Due to current source I1 current constant, so in the time of the transistorized minimizing by electric current of PMOS or increase, the electric current of the nmos pass transistor NM1 that flows through increases or reduce identical quantity on the contrary thereupon.Nmos device NM2 and NM1 form mirror current source, in order to reduce device 1/f noise, nmos pass transistor NM1 and NM2 are large-size devices, the breadth length ratio W/L value that simultaneously designs nmos pass transistor NM2 be NM1 device breadth length ratio W/L value N doubly, the electric current that transistor NM2 passes through is like this that transistor NM1 is by N times of electric current.Preferably, between transistor NM1 and NM2, form resistor R1 and capacitor C1 and form low pass filter, can filter the noise signal of audio frequency more than 20KHz, improved the signal to noise ratio (SNR) of preamplifier 400.In this embodiment, the nmos pass transistor NM2 that is positioned at output is large-size device, the chip current major part transistor NM2 that flows through.As an alternative, the RC low pass filter being connected between transistor NM1 and NM2 also can be realized with circuit structure.
According to preamplifier 400 of the present utility model, from first order PMOS amplifier to second level NMOS amplifier, circuit adopts image current source structure, the transmission of inside circuit signal adopts current signal, instead of voltage signal, solve on the one hand the direct current (DC) bias problem of output transistor NM2, avoid like this amplifier first order in existing US Patent No. 6888408B2 to the capacitive coupling problem of the second level, to make on the other hand integrated low pass filter between nmos device NM1 and NM2 become possibility.By increasing low pass filter, can filter the noise signal of audio frequency more than 20KHz, improve thus circuit output signal-to-noise ratio (SNR).By resistor R1 and capacitor C1 size are designed in the reasonable scope, can easily they be integrated on chip simultaneously.The typical gains that Fig. 5 shows preamplifier 400 distributes, and can find out that the above part signal of 20KHz is suppressed by RC low pass filter.
Preferably, this embodiment can use separately also and can be combined with other embodiment.
Fig. 6 illustrates according to the circuit diagram of the ECM of the utility model the 3rd embodiment CMOS preamplifier 600.In this embodiment, current source is realized in the mode of resistor R2, and other parts are identical with the second embodiment shown in Fig. 4.By resistor is used as to current source, can simplify the circuit structure of preamplifier, obtain high-gain with simple circuit structure, the ECM microphone preamplifier of small size.
Preferably, this embodiment can use separately also and can be combined with other embodiment.
Fig. 7 illustrates according to the circuit diagram of the ECM of the utility model the 4th embodiment CMOS preamplifier 700.In this embodiment, current source is realized with depletion type nmos transistor NM3, and other parts are identical with the second embodiment shown in Fig. 4.Preferably, current source is realized with depletion type nmos transistor NM3 and resistor R2.The drain electrode of depletion type nmos transistor NM3 is connected with the drain electrode of the second nmos pass transistor as one end of current source, the other end as current source after its grid is connected with source electrode is connected with the drain electrode of the transistorized source electrode of described PMOS and the first nmos pass transistor, and resistor R2 is connected between the source electrode and the described other end of transistor NM3.Resistor R2 plays negative feedback, makes the electric current of current source output more stable, and output current is very little with the variation of supply voltage.
Preferably, this embodiment can use separately also and can be combined with other embodiment.
Fig. 8 illustrates according to the circuit diagram of the ECM of the utility model the 5th embodiment CMOS preamplifier 800.In this embodiment, current source also can be realized with PMOS transistor, and other parts are identical with the second embodiment shown in Fig. 4.. preferably, this current source comprises second and the 3rd PMOS transistor PM2 and PM3 and reference current source Iref.
Preferably, this embodiment can use separately also and can use in conjunction with other embodiment.
The implementation method that it should be appreciated by those skilled in the art that current source also has multiple choices, can be in conjunction with being applied in preamplifier of the present utility model.
Fig. 9 illustrates according to the circuit diagram of the ECM of the utility model the 6th embodiment CMOS preamplifier 900.In this embodiment, form in the source of image current at the first and second nmos pass transistor NM1 and NM2, the source electrode of nmos pass transistor NM1 and NM2 is resistors in series Rs1 and Rs2 respectively.Like this, flowing through the electric current of nmos pass transistor NM1 and NM2 can be more symmetrical.Also can regulate the source voltage of PMOS transistor PM1 or the electric current of the PM1 that flows through, thereby regulate the gain of PMOS transistor PM1 simultaneously.
Preferably, this embodiment can use separately also and can be combined with other embodiment.
In order to save space and reducing costs, first order transistor and second level transistor are preferably integrated in and on chip, form integrated circuit lead.The preamplifier that is formed as integrated circuit lead is suitable for being applied in the very limited various applied environments in space, is particularly applied in electret ECM microphone.
Obviously; above-described embodiment of the present utility model is only for the utility model example is clearly described; and be not the restriction to execution mode of the present utility model; for those of ordinary skill in the field; can also make other changes in different forms on the basis of the above description; here cannot give all execution modes exhaustively, everyly belong to apparent variation or the still row in protection range of the present utility model of variation that the technical solution of the utility model extends out.
Claims (10)
1. an electret microphone high-gain preamplifier, this amplifier is made up of two-stage circuit, wherein first order amplifying circuit uses pmos source follower as input, second level amplifying circuit is to use NMOS commonsource amplifier, and first order amplifying circuit is realized with mirror current source to second level amplifying circuit.
2. an electret microphone high-gain preamplifier, this amplifier comprises PMOS transistor, the first and second nmos pass transistors, and current source,
It is characterized in that,
The transistorized grid of described PMOS is as the input of this amplifier, and the drain electrode of described the second nmos pass transistor is used as the output of this amplifier,
The first end of described current source is connected with the drain electrode of the second nmos pass transistor, and the second end is connected with the drain electrode of the transistorized source electrode of described PMOS and the first nmos pass transistor,
The grid of described the first and second nmos pass transistors connects, and
The source ground of the transistorized drain electrode of described PMOS and the first and second nmos pass transistors.
3. electret microphone as claimed in claim 1 or 2 high-gain preamplifier, is characterized in that, the transistorized grid of PMOS is by resistor or resistive device ground connection.
4. electret microphone as claimed in claim 1 or 2 high-gain preamplifier, is characterized in that, described current source is realized with the first resistor.
5. electret microphone as claimed in claim 1 or 2 high-gain preamplifier, is characterized in that, described current source is realized with depletion type nmos transistor and the second resistor.
6. electret microphone as claimed in claim 5 high-gain preamplifier, it is characterized in that, the drain electrode of described depletion type nmos transistor is as the first end of described current source, and the source series of described depletion type nmos transistor is connected the second end as described current source after connecting described the second resistor with its grid.
7. electret microphone as claimed in claim 1 or 2 high-gain preamplifier, is characterized in that, described current source is realized in the mode of two PMOS transistors and reference current source.
8. electret microphone as claimed in claim 2 high-gain preamplifier, is characterized in that, the source electrode of described the first and second nmos pass transistors is respectively by resistor or resistive device ground connection.
9. electret microphone as claimed in claim 2 high-gain preamplifier, is characterized in that, this preamplifier further comprises the low pass filter between the grid that is coupling in the first and second nmos devices.
10. an electret microphone, comprises electret microphone as claimed in claim 1 high-gain preamplifier.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420243692.8U CN203942499U (en) | 2014-05-13 | 2014-05-13 | For high-gain preamplifier and the electret microphone of electret microphone |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420243692.8U CN203942499U (en) | 2014-05-13 | 2014-05-13 | For high-gain preamplifier and the electret microphone of electret microphone |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN203942499U true CN203942499U (en) | 2014-11-12 |
Family
ID=51861783
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201420243692.8U Active CN203942499U (en) | 2014-05-13 | 2014-05-13 | For high-gain preamplifier and the electret microphone of electret microphone |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN203942499U (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103997303A (en) * | 2014-05-13 | 2014-08-20 | 北京燕东微电子有限公司 | High-gain pre-amplifier for electret microphone and electret microphone |
| CN111293995A (en) * | 2020-02-25 | 2020-06-16 | 华南理工大学 | Transistor equivalent transconductance improving amplifier circuit and chip |
| CN111431487A (en) * | 2020-04-14 | 2020-07-17 | 四川聚阳科技集团有限公司 | Low-noise microphone preamplifier circuit |
-
2014
- 2014-05-13 CN CN201420243692.8U patent/CN203942499U/en active Active
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103997303A (en) * | 2014-05-13 | 2014-08-20 | 北京燕东微电子有限公司 | High-gain pre-amplifier for electret microphone and electret microphone |
| CN111293995A (en) * | 2020-02-25 | 2020-06-16 | 华南理工大学 | Transistor equivalent transconductance improving amplifier circuit and chip |
| CN111293995B (en) * | 2020-02-25 | 2021-01-05 | 华南理工大学 | Transistor equivalent transconductance improving amplifier circuit and chip |
| CN111431487A (en) * | 2020-04-14 | 2020-07-17 | 四川聚阳科技集团有限公司 | Low-noise microphone preamplifier circuit |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US8610497B2 (en) | System and method for capacitive signal source amplifier | |
| CN104113293B (en) | A kind of high-gain low-noise difference trans-impedance amplifier | |
| CN104106269B (en) | Circuit for the loudspeaker of portable set | |
| CN103023444B (en) | Trans-impedance amplifier and current conversion voltage method thereof | |
| TW200735522A (en) | Single-end input to differential-ends output low noise amplifier | |
| CN101675669B (en) | Microphone amplifier | |
| US9083286B2 (en) | System and method for capacitive signal source amplifier | |
| CN105744452B (en) | MEMS microphone circuit | |
| US7224226B2 (en) | Amplifying device | |
| CN103338014A (en) | Operational amplifier circuits | |
| CN203942499U (en) | For high-gain preamplifier and the electret microphone of electret microphone | |
| CN103997303A (en) | High-gain pre-amplifier for electret microphone and electret microphone | |
| CN105305970A (en) | Dynamic transconductance compensation Class-AB audio power amplifier with low power consumption | |
| JP2010103842A (en) | Amplifier device | |
| CN106374858A (en) | High-speed differential amplification circuit | |
| CN106301242A (en) | Current multiplexing type radio-frequency amplifier circuit | |
| US9681211B2 (en) | System and method for a microphone amplifier | |
| CN106026948B (en) | A kind of high capacitance driving Low-Power CMOS trans-impedance amplifier | |
| CN106160730A (en) | Small-signal receiving front-end and method of reseptance | |
| CN105515536A (en) | Rail-to-rail amplifier | |
| TWI500259B (en) | Voltage controlling circuit | |
| CN107786175A (en) | A kind of broadband for photoreceiver is across resistance amplifying circuit | |
| CN107896096A (en) | Sampling hold circuit front-end wideband amplifier | |
| US9564857B2 (en) | Low noise amplifier and chip | |
| CN111277234A (en) | Power amplifier |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant |