Anti-interference electret microphone working circuit and electret microphone
By introducing field effect tube and π-shaped filter structure into the electret microphone, the problem of insufficient anti-interference ability of the electret microphone is solved, and effective filtering of electrostatic and WIFI interference is achieved to ensure the stable operation of the microphone.
Patent Information
- Application Number
- CN202422520167.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-18
- Publication Date
- 2025-08-08
- Estimated Expiration
- 2034-10-18
AI Technical Summary
The existing electret microphones have poor anti-interference ability and are easily affected by external interference signals, resulting in abnormal functions.
An anti-interference electret microphone working circuit is designed, using a field effect tube and a π-shaped filter structure, which isolates the gate, source and drain of the field effect tube through a resistor, and filters out WIFI interference signals with a π-shaped filter to enhance anti-static ability.
It effectively improves the anti-static interference capability of the electret microphone, can effectively filter out WIFI interference signals, and ensures that the microphone works normally.
Smart Images
Figure CN223207251U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of electret microphones, in particular to an anti-interference electret microphone working circuit and an electret microphone. Background Art
[0002] An electret microphone is a transducer that converts acoustic signals into electrical signals and is a type of condenser microphone. It consists of two components: acoustic-to-electrical conversion and impedance conversion. Its operating principle is based on the electret diaphragm used for acoustic-to-electrical conversion. Electret microphones are characterized by their small size, simple structure, excellent electroacoustic performance, and low price. They are widely used in cassette recorders, wireless microphones, and voice control circuits.
[0003] In practical applications, electret microphones are highly susceptible to interference signals. Due to design flaws in their circuit structure, existing electret microphones have poor anti-interference capabilities. When affected by interference signals, electret microphones are prone to malfunctioning and failing to meet customer requirements. Utility Model Content
[0004] Based on this, it is necessary to provide an anti-interference electret microphone working circuit and an electret microphone to address the problem that the electret microphone has poor anti-interference ability and is very likely to have functional abnormalities when affected by external interference signals and cannot meet customer requirements.
[0005] An anti-interference electret microphone working circuit includes a positive terminal, a negative terminal, a field effect transistor, an electret capacitor, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a first capacitor, a second capacitor, and a third capacitor;
[0006] The source of the field effect tube is respectively connected to one end of the second resistor and one end of the third capacitor, the gate of the field effect tube is connected to one end of the third resistor, the drain of the field effect tube is respectively connected to one end of the fourth resistor and one end of the fifth resistor, the other end of the third resistor is connected to the positive terminal of the electret capacitor, the other end of the second resistor is respectively connected to one end of the first resistor, one end of the first capacitor and one end of the second capacitor, the other end of the first capacitor and the other end of the first resistor are respectively connected to the positive terminal, the negative terminal of the electret capacitor, the other end of the fifth resistor, the other end of the fourth resistor, the other end of the second capacitor and the other end of the third capacitor are respectively connected to the negative terminal, the positive terminal is used to connect an external audio chip and an external power supply, and the negative terminal is grounded.
[0007] In the aforementioned anti-interference electret microphone operating circuit, the electret capacitor is composed of two relatively parallel metal plates separated by an insulating medium, one of which is provided with an electret diaphragm. When the electret diaphragm encounters an acoustic signal, it vibrates, causing the distance between the two metal plates to change. This changes the capacitance of the electret capacitor and outputs a changed electrical signal to the gate of the field-effect transistor via a third resistor. The field-effect transistor amplifies the electrical signal and outputs the amplified signal through the source of the field-effect transistor. The amplified signal is then output to an external audio chip via a second resistor, a first capacitor, and a positive terminal. Simultaneously, an external power supply can power the anti-interference electret microphone operating circuit via the positive terminal. When the anti-interference electret microphone operating circuit is operating, the gate, source, and drain of the field-effect transistor are isolated by resistors, effectively improving the field-effect transistor's ability to resist electrostatic interference signals. Furthermore, the second resistor, second capacitor, and third capacitor form a π-shaped filter that effectively filters out Wi-Fi interference signals.
[0008] In one embodiment, the field effect transistor is a junction field effect transistor.
[0009] In one embodiment, the resistance of the first resistor is 2.2 kΩ.
[0010] In one embodiment, the capacitance of the first capacitor is 1 μF.
[0011] In one embodiment, the resistance values of the second resistor and the third resistor are both 100Ω, and the resistance values of the fourth resistor and the fifth resistor are both 200Ω.
[0012] In one embodiment, the capacitance of the second capacitor is 10 pF, and the capacitance of the third capacitor is 33 pF.
[0013] An electret microphone using the above-mentioned anti-interference electret microphone working circuit, the electret microphone comprising a housing, a PCBA board and the electret capacitor, the PCBA board and the electret capacitor being arranged inside the housing, and the PCBA board being electrically connected to the electret capacitor;
[0014] The positive terminal, the negative terminal, the field effect transistor, the first resistor, the second resistor, the third resistor, the fourth resistor, the fifth resistor, the first capacitor, the second capacitor and the third capacitor are arranged on the PCBA board.
[0015] The above-mentioned electret microphone includes a housing, a PCBA board and an electret capacitor. Since the PCBA board is electrically connected to the electret capacitor, and a positive terminal, a negative terminal, a field-effect transistor, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a first capacitor, a second capacitor and a third capacitor are arranged on the PCBA board, the electret microphone can run the above-mentioned anti-interference electret microphone working circuit, has a strong anti-static signal interference capability, and can effectively filter out WIFI interference signals.
[0016] In one embodiment, the negative terminal and the housing are grounded at the same potential.
[0017] In one embodiment, the PCBA board includes a front layer, a middle layer and a back layer;
[0018] The front layer is used to make the positive electrode terminal and the negative electrode terminal;
[0019] The middle layer is provided between the front layer and the back layer, and the middle layer adopts a paving design;
[0020] The reverse layer is used to manufacture the field effect transistor, the first resistor, the second resistor, the third resistor, the fourth resistor, the fifth resistor, the first capacitor, the second capacitor, and the third capacitor.
[0021] In one embodiment, the front layer, the middle layer and the back layer are all designed with vias. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Figure 1 This is a working principle diagram of the anti-interference electret microphone working circuit of the utility model;
[0023] Figure 2 This is a schematic diagram of the explosion structure in the electret microphone of the present invention;
[0024] Figure 3 This is a schematic diagram of the structure of the PCBA board in the electret microphone of the present invention. DETAILED DESCRIPTION
[0025] To make the above-mentioned objects, features, and advantages of the present invention more clearly understood, the following detailed description of specific embodiments of the present invention is provided in conjunction with the accompanying drawings. The following description sets forth many specific details to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art may make similar modifications without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.
[0026] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be an intermediate element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be an intermediate element at the same time. In contrast, when an element is referred to as being "directly on" another element, there is no intermediate element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only."
[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains. The terms used herein in the specification of this invention are intended only to describe specific embodiments and are not intended to limit this invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.
[0028] The utility model discloses an anti-interference electret microphone working circuit and an electret microphone.
[0029] like Figure 1 As shown, the anti-interference electret microphone working circuit includes a positive terminal, a negative terminal, a field effect transistor Q1, an electret capacitor C0, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a first capacitor C1, a second capacitor C2 and a third capacitor C3.
[0030] The source of the field-effect transistor Q1 is respectively connected to one end of the second resistor R2 and one end of the third capacitor C3, the gate of the field-effect transistor Q1 is connected to one end of the third resistor R3, the drain of the field-effect transistor Q1 is respectively connected to one end of the fourth resistor R4 and one end of the fifth resistor R5, the other end of the third resistor R3 is connected to the positive terminal of the electret capacitor C0, the other end of the second resistor R2 is respectively connected to one end of the first resistor R1, one end of the first capacitor C1 and one end of the second capacitor C2, the other end of the first capacitor C1 and the other end of the first resistor R1 are respectively connected to the positive terminal, the negative terminal of the electret capacitor C0, the other end of the fifth resistor R5, the other end of the fourth resistor R4, the other end of the second capacitor C2 and the other end of the third capacitor C3 are respectively connected to the negative terminal, the positive terminal is used to connect to an external audio chip and an external power supply, and the negative terminal is grounded.
[0031] The first resistor R1 is used for impedance matching and power supply; the π-shaped filter composed of the second resistor R2, the second capacitor C2 and the third capacitor C3 can filter out WiFi interference signals; the third resistor R3 can eliminate the gate oscillation of the field-effect transistor Q1; the fourth resistor R4 and the fifth resistor R5 can balance the operating voltage of the field-effect transistor Q1 to prevent it from being broken down by static electricity; the first capacitor C1 is used to couple the audio signal; the field-effect transistor Q1 is used for signal amplification, and the electret capacitor C0 is used to convert the sound wave signal into an audio signal.
[0032] In the aforementioned anti-interference electret microphone operating circuit, the electret capacitor is composed of two relatively parallel metal plates separated by an insulating medium, one of which is provided with an electret diaphragm. When the electret diaphragm encounters an acoustic signal, it vibrates, causing the distance between the two metal plates to change. This changes the capacitance of the electret capacitor, which then outputs a changed audio signal to the gate of a field-effect transistor via a third resistor. The field-effect transistor amplifies the audio signal and outputs the amplified audio signal through its source. The amplified audio signal is then output to an external audio chip via a second resistor, a first capacitor, and a positive terminal. Simultaneously, an external power supply can power the anti-interference electret microphone operating circuit via the positive terminal. When the anti-interference electret microphone operating circuit is operating, the gate, source, and drain of the field-effect transistor are isolated by resistors, effectively enhancing the field-effect transistor's anti-static interference capability. Furthermore, the second resistor, second capacitor, and third capacitor form a π-shaped filter that effectively filters out Wi-Fi interference signals.
[0033] Among them, the type of field effect transistor Q1 can be selected according to actual needs. Preferably, the field effect transistor Q1 is a junction field effect transistor. Furthermore, the resistance values of the first resistor R1, the second resistor R2, the third resistor R3, the fourth resistor R4, and the fifth resistor R5, as well as the capacitance values of the first capacitor C1, the second capacitor C2, and the third capacitor C3 can be adjusted according to actual needs. Preferably, the resistance value of the first resistor R1 is 2.2kΩ, the capacitance value of the first capacitor C1 is 1μF, the resistance values of the second resistor R2 and the third resistor R3 are both 100Ω, the resistance values of the fourth resistor R4 and the fifth resistor R5 are both 200Ω, the capacitance value of the second capacitor C2 is 10pF, and the capacitance value of the third capacitor C3 is 33pF.
[0034] The utility model also discloses an electret microphone using the anti-interference electret microphone working circuit.
[0035] like Figure 2As shown, the electret microphone includes a housing, a PCBA board and the above-mentioned electret capacitor C0. The PCBA board and the electret capacitor C0 are arranged inside the housing, and the PCBA board is electrically connected to the electret capacitor C0. The electret capacitor C0 includes a diaphragm, a gasket and a back plate; the PCBA board is provided with a positive terminal, a negative terminal, a field effect transistor Q1, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a first capacitor C1, a second capacitor C2 and a third capacitor C3.
[0036] The above-mentioned electret microphone includes a housing, a PCBA board and an electret capacitor. Since the PCBA board is electrically connected to the electret capacitor, and a positive terminal, a negative terminal, a field-effect transistor, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a first capacitor, a second capacitor and a third capacitor are arranged on the PCBA board, the electret microphone can run the above-mentioned anti-interference electret microphone working circuit, has a strong anti-static signal interference capability, and can effectively filter out WIFI interference signals.
[0037] Furthermore, the negative terminal of the anti-interference electret microphone working circuit is grounded to the same potential as the housing. By grounding the negative terminal of the anti-interference electret microphone working circuit to the same potential as the housing, the shielding effect of the anti-interference electret microphone working circuit can be enhanced, reducing power frequency interference and Wi-Fi interference.
[0038] Furthermore, the diaphragm is used to convert acoustic signals into mechanical vibration signals, and the gasket is used to support the diaphragm and the backplate, which is used to convert the mechanical vibration signals into audio signals. Furthermore, the electret microphone also includes a copper ring and a plastic ring. The copper ring transmits weak audio signals to the gate of the field-effect transistor Q1, while the plastic ring secures the copper ring to the electret backplate, isolating the copper ring, the electret backplate, and the housing.
[0039] like Figure 3 As shown, the PCBA board includes a front layer, a middle layer, and a back layer. The front layer is used to form the positive and negative terminals. The middle layer is located between the front and back layers and is designed as a grounding layer. The back layer is used to form the field-effect transistor Q1, the first resistor R1, the second resistor R2, the third resistor R3, the fourth resistor R4, the fifth resistor R5, the first capacitor C1, the second capacitor C2, and the third capacitor C3. By arranging the front, middle, and back layers on the PCBA board and grounding the middle layer, the shielding effect of the anti-interference electret microphone's operating circuit can be enhanced. The middle layer reduces the signal loop area of the front and back layers, improving signal integrity. The distributed capacitance formed effectively suppresses 50Hz interference signals.
[0040] Furthermore, the front, middle, and back layers are all designed with vias. Positive and negative vias can be set on the front, middle, and back layers. The positive vias are connected to the positive terminals, and the negative vias are connected to the negative terminals. The via design effectively improves the signal integrity of the PCBA board.
[0041] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0042] The above-described embodiments merely represent several implementations of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the utility model patent. It should be noted that a person skilled in the art would be able to make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements fall within the scope of protection of the present invention. Therefore, the scope of protection of the present utility model patent shall be determined by the appended claims.
Claims
1. An anti-interference electret microphone working circuit, characterized in that: including a positive terminal, a negative terminal, a field effect transistor, an electret capacitor, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a first capacitor, a second capacitor and a third capacitor; The source of the field effect tube is respectively connected to one end of the second resistor and one end of the third capacitor, the gate of the field effect tube is connected to one end of the third resistor, the drain of the field effect tube is respectively connected to one end of the fourth resistor and one end of the fifth resistor, the other end of the third resistor is connected to the positive terminal of the electret capacitor, the other end of the second resistor is respectively connected to one end of the first resistor, one end of the first capacitor and one end of the second capacitor, the other end of the first capacitor and the other end of the first resistor are respectively connected to the positive terminal, the negative terminal of the electret capacitor, the other end of the fifth resistor, the other end of the fourth resistor, the other end of the second capacitor and the other end of the third capacitor are respectively connected to the negative terminal, the positive terminal is used to connect an external audio chip and an external power supply, and the negative terminal is grounded.
2. The anti-interference electret microphone working circuit according to claim 1, characterized in that: The field effect transistor is a junction field effect transistor.
3. The anti-interference electret microphone working circuit according to claim 1, characterized in that: The resistance of the first resistor is 2.2 kΩ.
4. The anti-interference electret microphone working circuit according to claim 1, characterized in that: The capacitance of the first capacitor is 1 μF.
5. The anti-interference electret microphone working circuit according to claim 1, characterized in that: The resistance values of the second resistor and the third resistor are both 100Ω, and the resistance values of the fourth resistor and the fifth resistor are both 200Ω.
6. The anti-interference electret microphone working circuit according to claim 1, characterized in that: The capacitance of the second capacitor is 10 pF, and the capacitance of the third capacitor is 33 pF.
7. An electret microphone using the anti-interference electret microphone working circuit according to any one of claims 1 to 6, characterized in that: The electret microphone includes a housing, a PCBA board and the electret capacitor, wherein the PCBA board and the electret capacitor are arranged inside the housing, and the PCBA board is electrically connected to the electret capacitor; The positive terminal, the negative terminal, the field effect transistor, the first resistor, the second resistor, the third resistor, the fourth resistor, the fifth resistor, the first capacitor, the second capacitor and the third capacitor are arranged on the PCBA board.
8. The electret microphone according to claim 7, wherein: The negative terminal and the housing are grounded at the same potential.
9. The electret microphone according to claim 8, characterized in that The PCBA board includes a front layer, a middle layer and a back layer; The front layer is used to make the positive electrode terminal and the negative electrode terminal; The middle layer is provided between the front layer and the back layer, and the middle layer adopts a paving design; The reverse layer is used to manufacture the field effect transistor, the first resistor, the second resistor, the third resistor, the fourth resistor, the fifth resistor, the first capacitor, the second capacitor, and the third capacitor.
10. The electret microphone according to claim 9, characterized in that The front layer, the middle layer and the back layer are all designed with vias.