CN111800717A - Anti radio frequency interference circuit and electret microphone - Google Patents
Anti radio frequency interference circuit and electret microphone Download PDFInfo
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- CN111800717A CN111800717A CN201910504750.5A CN201910504750A CN111800717A CN 111800717 A CN111800717 A CN 111800717A CN 201910504750 A CN201910504750 A CN 201910504750A CN 111800717 A CN111800717 A CN 111800717A
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- sound
- resistor
- radio frequency
- frequency interference
- pressure signal
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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
- H04R19/00—Electrostatic transducers
- H04R19/01—Electrostatic transducers characterised by the use of electrets
- H04R19/016—Electrostatic transducers characterised by the use of electrets for microphones
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R2201/00—Details of transducers, loudspeakers or microphones covered by H04R1/00 but not provided for in any of its subgroups
- H04R2201/003—Mems transducers or their use
Abstract
The invention is suitable for the technical field of electronics, and provides an anti-radio-frequency interference circuit and an electret microphone. Wherein, anti radio frequency interference circuit includes: the sound-pressure signal source is used for outputting a sound-pressure signal, and the sound-pressure signal source is used for outputting a sound-pressure signal; the anti-interference unit includes: a first resistor and a first capacitor; one end of the sound pressure signal source is connected with the grid electrode of the sound-electricity converter through a first resistor connected in series, and the other end of the sound pressure signal source is grounded with the source electrode of the sound-electricity converter; a first capacitor is connected in series between the drain electrode and the source electrode of the acoustic-electric converter.
Description
Technical Field
The invention belongs to the technical field of electronics, and particularly relates to a radio frequency interference resistant circuit and an electret microphone.
Background
In the process of rapidly developing mobile portable communication devices such as cellular phones, a microphone, which is one of essential elements of the mobile portable communication devices, is increasingly demanded.
Meanwhile, Radio Frequency Identification (RFID) technology and its application are in a rapidly rising period and are widely applied in the market. Radio frequency identification is a non-contact automatic identification technology that automatically identifies a target object and obtains relevant data through radio frequency signals.
The existing electret microphone usually has a low-pass filter composed of a resistor and a capacitor, and the structure can suppress radio frequency (200 MHz-2 GHz) interference, but when the microphone works in a strong radiation field, the capability of suppressing radio frequency interference can not meet the requirement of a client.
Disclosure of Invention
In view of this, embodiments of the present invention provide an anti-rf interference circuit and an electret microphone to solve the problem of electronic interference of rf signals in the electret microphone.
A first aspect of an embodiment of the present invention provides an anti-radio frequency interference circuit, including:
the system comprises an acoustic-electric converter and an anti-interference unit;
the sound-electricity converter is used for converting sound pressure signals output by the sound pressure signal source into voltage source signals, and the anti-interference unit is used for performing anti-radio frequency interference processing on the voltage source signals
The anti-jamming unit includes: a first resistor and a first capacitor;
one end of the sound pressure signal source is connected with the grid electrode of the sound-electricity converter through the first resistor in series connection, and the other end of the sound pressure signal source is grounded behind the source electrode of the sound-electricity converter;
the first capacitor is connected in series between the drain electrode and the source electrode of the acoustic-electric converter.
In one embodiment, the interference rejection unit further comprises: a second resistor, a third resistor and a second capacitor;
and the source electrode and the drain electrode of the acoustic-electric converter are respectively connected in series with the second resistor and the third resistor and then connected in parallel with the second capacitor.
In one embodiment, one end of the third resistor is connected with the drain electrode of the acoustic-electric converter, and the other end of the third resistor is connected with a power supply and a circuit output end; the power supply is used for providing working voltage of the sound-electricity converter;
one end of the second resistor is connected with the source electrode of the sound-electricity converter, and the other end of the second resistor is grounded.
In one embodiment, the first resistance is 1000 Ω,
the first capacitance is 2pF or 3.6 pF.
In one embodiment, the second resistance and the third resistance are 100 Ω,
the second capacitance is 10pF or 8.2 pF.
A second aspect of an embodiment of the present invention provides an electret microphone, including:
the anti-radio frequency interference circuit of the first aspect above.
In one embodiment, the electret microphone further comprises: copper ring, cavity, back plate, gasket, diaphragm, shell and dust screen.
In one embodiment, the process of converting the sound signal of the electret microphone into the sound pressure signal includes: the sound signal is transmitted to the diaphragm through the dust screen and the sound inlet hole at the bottom of the shell, so that the diaphragm vibrates, the combined capacitance capacity among the diaphragm, the gasket and the back electrode plate is changed, and the sound pressure signal is generated;
in one embodiment, the anti-radio frequency interference circuit further includes: a gate ring; the grid ring is connected with the grid of the acoustic-electric converter in the radio frequency interference resisting circuit;
the generated sound pressure signal is transmitted to the grid ring through the copper ring.
According to the embodiment of the invention, the resistor is arranged between the sound pressure signal source and the grid electrode of the sound-electricity converter, so that the ringing phenomenon in the grid electrode of the sound-electricity converter can be reduced, the electromagnetic interference is reduced, and the current limiting effect can be realized on the charging and discharging of the grid electrode capacitor.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the embodiments or the prior art descriptions will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise.
Fig. 1 is a schematic diagram of a logic structure of an anti-rfi circuit according to an embodiment of the present invention;
fig. 2 is a schematic circuit diagram of an anti-rfi circuit according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of a component structure of an electret microphone according to an embodiment of the present invention;
fig. 4 is a top view of a circuit structure of the anti-rfi circuit according to an embodiment of the present invention.
Detailed Description
In order to make the technical solutions of the present invention better understood by those skilled in the art, the technical solutions in the embodiments of the present invention will be clearly described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The terms "comprises" and "comprising," and any variations thereof, in the description and claims of this invention and the above-described drawings are intended to cover non-exclusive inclusions. For example, a process, method, or system, article, or apparatus that comprises a list of steps or elements is not limited to only those steps or elements listed, but may alternatively include other steps or elements not listed, or inherent to such process, method, article, or apparatus.
Example one
Referring to fig. 1, an embodiment of an anti-rfi circuit in an embodiment of the present application includes:
the system comprises an acoustic-electric converter and an anti-interference unit;
the sound-electricity converter is used for converting a sound pressure signal output by a sound pressure signal source into a voltage source signal, and the anti-interference unit is used for performing anti-radio frequency interference processing on the voltage source signal;
the anti-jamming unit includes: a first resistor R1 and a first capacitor C1;
one end of the sound pressure signal source is connected with the grid electrode of the sound-electricity converter through the first resistor R1 connected in series, and the other end of the sound pressure signal source is grounded with the source electrode of the sound-electricity converter;
illustratively, in practical applications, the acoustic-electric converter may be a field effect Transistor FET (FET).
For example, the first resistor R1 may be 1000 Ω, and the first resistor R1 may reduce ringing in the gate of the acoustic-electric converter, reduce electromagnetic interference, and also may perform a current limiting function for charging and discharging the gate capacitor.
The first capacitor C1 is connected in series between the drain and the source of the acoustic-electric converter, and is exemplarily 2pF or 3.6 pF. It should be understood that the specific values listed in the present application are only exemplary, and in practical applications, the specific values can be adjusted to approximate values according to practical requirements, and any minor modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present application still fall within the scope of the technical solution of the present application.
Referring to fig. 2, an electronic circuit diagram of resisting radio frequency (15 MHz-6 GHz) interference in practical application can be shown in fig. 2, wherein in the diagram, the FET is an acoustic-electric converter, the G terminal of the FET represents the gate of the acoustic-electric converter, the D terminal of the FET represents the drain of the acoustic-electric converter, and the S terminal of the FET represents the source of the acoustic-electric converter.
In an implementation manner of the embodiment of the present application, the interference rejection unit further includes: a second resistor R2, a third resistor R3 and a second capacitor C2;
the source and the drain of the acoustic-electric converter are respectively connected in series with the second resistor R2 and the third resistor R3, and then are connected in parallel with the second capacitor C2.
One end of the third resistor R3 is connected with the drain of the sound-electricity converter, and the other end of the third resistor R3 is connected with a power supply VCC and a circuit OUTPUT end OUTPUT; the power supply VCC is used for providing working voltage of the acoustic-electric converter;
one end of the second resistor R2 is connected to the source of the acoustic-electric converter, and the other end of the second resistor R2 is connected to ground GND.
Illustratively, the second resistor R2 and the third resistor R3 are 100 Ω, and the second capacitor is 10pF or 8.2 pF. It should be understood that the specific values listed in the present application are only exemplary, and in practical applications, the specific values can be adjusted to approximate values according to practical requirements, and any minor modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present application still fall within the scope of the technical solution of the present application.
According to the embodiment of the invention, the resistor is arranged between the sound pressure signal source and the grid electrode of the sound-electricity converter, so that the ringing phenomenon in the grid electrode of the sound-electricity converter can be reduced, the electromagnetic interference is reduced, and the current limiting effect can be realized on the charging and discharging of the grid electrode capacitor. In practical applications, after the anti-radio frequency interference circuit is installed in the electret microphone, the Electro Magnetic Compatibility (EMC) is tested, which means that the electromagnetic energy generated by the device does not interfere with or interfere with other devices. The result shows that the anti-radio frequency interference circuit can meet the requirement that the immunity of the microphone is below 42dBm in the frequency bands of 15-80 MHz, 80-1000 MHz and 1 GHz-6 GHz.
Example two
Referring to fig. 3, an embodiment of an electret microphone in the embodiment of the present application includes:
the electret microphone in the embodiment of the application includes: the anti-radio frequency interference circuit comprises a radio frequency interference circuit, a copper ring, a cavity, a back plate, a gasket, a diaphragm, a shell and a dust screen.
For details of the radio frequency interference resistant circuit in the embodiment of the present application, reference may be made to the first embodiment, and details are not described herein.
For example, in practical applications, the anti-radio frequency interference circuit may integrate all devices on the circuit board by an automatic chip mounting technique, so as to form a "circuit board assembly". The circuit board assembly is formed by packaging all the components by a shell through a pressing method to realize the conversion of sound signals into electric signals.
In one embodiment, the process of converting the sound signal of the electret microphone into the sound pressure signal includes: the sound signal is transmitted to the diaphragm through the dust screen and the sound inlet hole at the bottom of the shell, so that the diaphragm vibrates, the combined capacitance capacity among the diaphragm, the gasket and the back electrode plate is changed, and the sound pressure signal is generated;
referring to fig. 4, in an embodiment, the anti-rfi circuit further includes: a gate ring; the grid ring is connected with the grid of the acoustic-electric converter in the radio frequency interference resisting circuit; the voltage source signal generated as described above is transmitted to the gate ring through the copper ring.
In practical application, the equivalent voltage source signal of the above mentioned sound signal is transmitted to the gate ring of the circuit board assembly through the copper ring, and then enters the acoustoelectric converter FET, and is outputted from two pads of the circuit board assembly after being converted.
For example, the electret microphone in the embodiment of the present application satisfies the requirement of noise immunity below 42dBm in the frequency bands of 15-80 MHz, 80-1000 MHz, and 1 GHz-6 GHz, and can pass the current EMC test of the european union.
The above-mentioned embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the same; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not substantially depart from the spirit and scope of the embodiments of the present invention, and are intended to be included within the scope of the present invention.
Claims (9)
1. An anti-radio frequency interference circuit, comprising:
the system comprises an acoustic-electric converter and an anti-interference unit;
the sound-electricity converter is used for converting a sound pressure signal output by a sound pressure signal source into a voltage source signal, and the anti-interference unit is used for performing anti-radio frequency interference processing on the voltage source signal;
the anti-jamming unit includes: a first resistor and a first capacitor;
one end of the sound pressure signal source is connected with the grid electrode of the sound-electricity converter through the first resistor in series connection, and the other end of the sound pressure signal source is grounded behind the source electrode of the sound-electricity converter;
the first capacitor is connected in series between the drain electrode and the source electrode of the acoustic-electric converter.
2. The anti-radio frequency interference circuit according to claim 1,
the anti-jamming unit further comprises: a second resistor, a third resistor and a second capacitor;
and the source electrode and the drain electrode of the acoustic-electric converter are respectively connected in series with the second resistor and the third resistor and then connected in parallel with the second capacitor.
3. The anti-radio frequency interference circuit according to claim 2,
one end of the third resistor is connected with the drain electrode of the sound-electricity converter, and the other end of the third resistor is connected with the output end of the power supply and the circuit; the power supply is used for providing working voltage of the sound-electricity converter;
one end of the second resistor is connected with the source electrode of the sound-electricity converter, and the other end of the second resistor is grounded.
4. The anti-radio frequency interference circuit according to claim 1,
the first resistance is 1000 omega,
the first capacitance is 2pF or 3.6 pF.
5. The anti-radio frequency interference circuit according to claim 2,
the second resistance and the third resistance are 100 omega,
the second capacitance is 10pF or 8.2 pF.
6. An electret microphone, comprising:
the anti-radio frequency interference circuit of any one of claims 1 to 5.
7. The electret microphone of claim 6,
the electret microphone further includes: copper ring, cavity, back plate, gasket, diaphragm, shell and dust screen.
8. The electret microphone of claim 7,
the process of converting the sound signal of the electret microphone into the sound pressure signal comprises the following steps: the sound signal is transmitted to the diaphragm through the dust screen and the sound inlet hole at the bottom of the shell, so that the diaphragm vibrates, the combined capacitance capacity between the diaphragm, the gasket and the back plate is changed, and the sound pressure signal is generated.
9. The electret microphone of claim 8,
the anti-radio frequency interference circuit further comprises: a gate ring; the grid ring is connected with the grid of the acoustic-electric converter in the radio frequency interference resisting circuit;
the generated sound pressure signal is transmitted to the grid ring through the copper ring.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910504750.5A CN111800717A (en) | 2019-06-12 | 2019-06-12 | Anti radio frequency interference circuit and electret microphone |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910504750.5A CN111800717A (en) | 2019-06-12 | 2019-06-12 | Anti radio frequency interference circuit and electret microphone |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN111800717A true CN111800717A (en) | 2020-10-20 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201910504750.5A Pending CN111800717A (en) | 2019-06-12 | 2019-06-12 | Anti radio frequency interference circuit and electret microphone |
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| CN (1) | CN111800717A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113691915A (en) * | 2021-08-12 | 2021-11-23 | 湖南捷力泰科技有限公司 | Acoustic-electric conversion structure, electric signal amplification circuit and dual-mode microphone |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113691915A (en) * | 2021-08-12 | 2021-11-23 | 湖南捷力泰科技有限公司 | Acoustic-electric conversion structure, electric signal amplification circuit and dual-mode microphone |
| CN113691915B (en) * | 2021-08-12 | 2024-02-27 | 湖南捷力泰科技有限公司 | Acoustic-electric conversion structure, electric signal amplifying circuit and dual-mode microphone |
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Application publication date: 20201020 |