A kind of ultra-low noise microphone gain preamplifier circuit

Abstract

The application provides a kind of ultra-low noise microphone gain preamplifier circuit, it is related to microphone field, including pickup head, input terminal, JFET buffer module, voltage stabilizing filter module, capacitive coupling module, amplification module and output terminal, the pickup head is connected with the input terminal of input terminal, the output terminal of input terminal is connected with the input terminal of JFET buffer module, the output terminal of JFET buffer module is connected with the input terminal of voltage stabilizing filter module, the input terminal of capacitive coupling module, the output terminal of voltage stabilizing filter module, the output terminal of capacitive coupling module is connected with the input terminal of amplification module respectively, the output terminal of amplification module is connected with the output terminal;The utility model increases amplification module in originally's microphone gain preamplifier circuit, can inhibit power noise intensity by amplification module, improve common-mode rejection ratio, strong anti-interference ability, distortion THD is small, and noise processing effect is good.

Description

Technical Field

[0001] This application relates to the field of microphones, and more specifically, to an ultra-low noise floor microphone gain preamplifier circuit. Background Technology

[0002] The microphone preamplifier (MPA) is one of the most critical and challenging components in an audio system because it needs to handle extremely weak (μV to mV), high-impedance (especially for condenser microphones), and easily interfered-with microphone signals. Its design quality directly determines the noise floor, dynamic range, and sound clarity of the entire audio chain. Current microphone preamplifiers have poor noise handling capabilities, thus requiring improvement. Summary of the Invention

[0003] The purpose of this application is to provide an ultra-low noise microphone gain preamplifier circuit that can solve the above-mentioned technical problems.

[0004] This application provides an ultra-low noise microphone gain preamplifier circuit, including a pickup head, an input terminal, a JFET buffer module, a voltage regulator and filter module, a capacitive coupling module, an amplification module, and an output terminal. The pickup head is connected to the input terminal of the input terminal, the output terminal of the input terminal is connected to the input terminal of the JFET buffer module, the output terminal of the JFET buffer module is connected to the input terminals of the voltage regulator and filter module and the capacitive coupling module, the output terminals of the voltage regulator and filter module and the capacitive coupling module are respectively connected to the input terminal of the amplification module, and the output terminal of the amplification module is connected to the output terminal.

[0005] Preferably, the JFET buffer module includes a field-effect transistor Q3, the gate (G) of the field-effect transistor Q3 is connected to the output terminal of the input terminal, the source (S) of the field-effect transistor Q3 is connected to the voltage regulation and filtering module and the capacitive coupling module, and the drain (D) of the field-effect transistor Q3 is connected to the voltage regulation and filtering module and the capacitive coupling module.

[0006] Preferably, the capacitive coupling module includes capacitor C4, capacitor C5, resistor R5, and resistor R6. One end of capacitor C4 is connected to the source (S) terminal of the field-effect transistor Q3, and the other end of capacitor C4 is connected to one end of resistor R5 and the amplification module. The other end of resistor R5 is connected to one end of resistor R6, and the other end of resistor R6 is connected to one end of capacitor C5 and the amplification module. The other end of capacitor C5 is connected to the drain (D) terminal of the field-effect transistor Q3.

[0007] Preferably, the voltage regulation and filtering module includes resistors R7, R8, R9, and R10, capacitors EC1, EC2, and EC196, and diode ZD1. One end of resistor R10 is connected to the source (S) terminal of the field-effect transistor Q3, and the other end of resistor R10 is connected to one end of capacitor EC2, one end of diode ZD1, one end of capacitor EC1, and one end of capacitor EC196. One end of resistor R9 is connected to the drain (D) terminal of the field-effect transistor Q3, and the other end of resistor R9 is connected to the other end of capacitor EC2 and one end of resistor R8. The other end of resistor R8 is connected to the other end of diode ZD1, the other end of capacitor EC1, and one end of resistor R7. The other end of resistor R7 is connected to the other end of capacitor EC196 and the amplification module.

[0008] Preferably, the amplification module includes transistors Q1 and Q2, resistors R1, R2, R3, and R4, and capacitors C1, C2, C3, and C14. The base (B) of transistor Q1 is connected to one end of resistor R5. The collector (C) of transistor Q1 is connected to one end of resistor R3, one end of resistor R4, the collector (C) of transistor Q2, and one end of resistor R6. The emitter (E) of transistor Q1 is connected to one end of capacitor C2, the other end of resistor R3, and one end of resistor R1. The base (B) of transistor Q2 is connected to one end of capacitor C5. The emitter (E) of transistor Q2 is connected to the other end of resistor R4, one end of capacitor R2, and one end of capacitor C3. The other ends of capacitors C2 and C3 are grounded. One end of capacitor C14 is grounded, and the other end of capacitor C14 is connected to the other end of resistor R1. One end of capacitor C1 is grounded, and the other end of capacitor C1 is connected to the other end of resistor R2. The other ends of resistors R1 and R2 are respectively connected to the output terminal.

[0009] Preferably, the transistor Q1 and the transistor Q2 are both MMBT5087LT1G.

[0010] Preferably, the field-effect transistor Q3 is model J202 SOT-23.

[0011] The beneficial effects of this utility model are:

[0012] This invention provides an ultra-low noise floor microphone gain preamplifier circuit, including a pickup head, an input terminal, a JFET buffer module, a voltage regulator and filter module, a capacitive coupling module, an amplification module, and an output terminal. The pickup head is connected to the input terminal of the input terminal, the output terminal of the input terminal is connected to the input terminal of the JFET buffer module, the output terminal of the JFET buffer module is connected to the input terminals of the voltage regulator and filter module and the capacitive coupling module, the output terminals of the voltage regulator and filter module and the capacitive coupling module are respectively connected to the input terminal of the amplification module, and the output terminal of the amplification module is connected to the output terminal. This invention adds an amplification module to the original microphone gain preamplifier circuit, which can suppress strong power supply noise, improve the common-mode rejection ratio, enhance anti-interference ability, reduce THD, and improve noise processing effect. Attached Figure Description

[0013] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 This is the circuit schematic diagram of this utility model. Detailed Implementation

[0015] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0016] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0017] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0018] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this application is in use. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. In addition, the terms "first," "second," and "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0019] Furthermore, terms such as "horizontal," "vertical," and "sag" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0020] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "set up," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0021] like Figure 1 As shown, an ultra-low noise floor microphone gain preamplifier circuit includes a pickup head, an input terminal, a JFET buffer module, a voltage regulator and filter module, a capacitive coupling module, an amplification module, and an output terminal. The pickup head is connected to the input terminal of the input terminal, the output terminal of the input terminal is connected to the input terminal of the JFET buffer module, the output terminal of the JFET buffer module is connected to the input terminals of the voltage regulator and filter module and the capacitive coupling module, the output terminals of the voltage regulator and filter module and the capacitive coupling module are respectively connected to the input terminal of the amplification module, and the output terminal of the amplification module is connected to the output terminal. This invention adds an amplification module to the original microphone gain preamplifier circuit, which can suppress strong power supply noise, improve the common-mode rejection ratio, enhance anti-interference ability, reduce distortion (THD), and improve noise processing effect.

[0022] In this embodiment, the JFET buffer module includes a field-effect transistor Q3. The gate (G) of the field-effect transistor Q3 is connected to the output terminal of the input terminal. The source (S) of the field-effect transistor Q3 is connected to the voltage regulation and filtering module and the capacitive coupling module, respectively. The drain (D) of the field-effect transistor Q3 is connected to the voltage regulation and filtering module and the capacitive coupling module, respectively. The field-effect transistor Q3 of this invention features high impedance input, low noise conversion, signal isolation, and provides high-quality audio signals.

[0023] In this embodiment, the capacitive coupling module includes capacitor C4, capacitor C5, resistor R5, and resistor R6. One end of capacitor C4 is connected to the source (S) terminal of the field-effect transistor Q3, and the other end of capacitor C4 is connected to one end of resistor R5 and the amplification module. The other end of resistor R5 is connected to one end of resistor R6, and the other end of resistor R6 is connected to one end of capacitor C5 and the amplification module. The other end of capacitor C5 is connected to the drain (D) terminal of the field-effect transistor Q3. The capacitors C4, C5, and CBB coupling capacitor of this invention result in lower signal distortion and lower high-frequency loss, and the CBB polypropylene film also reduces signal distortion.

[0024] In this embodiment, the voltage regulation and filtering module includes resistors R7, R8, R9, and R10, capacitors EC1, EC2, and EC196, and diode ZD1. One end of resistor R10 is connected to the source (S) terminal of the field-effect transistor Q3, and the other end of resistor R10 is connected to one end of capacitor EC2, one end of diode ZD1, one end of capacitor EC1, and one end of capacitor EC196. One end of resistor R9 is connected to the drain (D) terminal of the field-effect transistor Q3, and the other end of resistor R9 is connected to the other end of capacitor EC2 and one end of resistor R8. The other end of resistor R8 is connected to the other end of diode ZD1, the other end of capacitor EC1, and one end of resistor R7. The other end of resistor R7 is connected to the other end of capacitor EC196 and the amplification module. The voltage regulation and filtering module of this invention can filter signals, making the signals clearer.

[0025] In this embodiment, the amplification module includes transistors Q1 and Q2, resistors R1, R2, R3, and R4, and capacitors C1, C2, C3, and C14. The base (B) of transistor Q1 is connected to one end of resistor R5. The collector (C) of transistor Q1 is connected to one end of resistor R3, one end of resistor R4, the collector (C) of transistor Q2, and one end of resistor R6. The emitter (E) of transistor Q1 is connected to one end of capacitor C2, the other end of resistor R3, and one end of resistor R1. The base (B) of transistor Q2 is connected to one end of capacitor C5. The emitter (E) of transistor Q2 is connected to the other end of resistor R4, one end of capacitor R2, and one end of capacitor C3. The other ends of capacitors C2 and C3 are grounded. One end of capacitor C14 is grounded, and the other end of capacitor C14 is connected to the other end of resistor R1. One end of capacitor C1 is grounded, and the other end of capacitor C1 is connected to the other end of resistor R2. The other ends of resistors R1 and R2 are respectively connected to the output terminal.

[0026] In this embodiment, the transistor Q1 and the transistor Q2 are both MMBT5087LT1G.

[0027] In this embodiment, the field-effect transistor Q3 is model J202 SOT-23.

[0028] Performance specifications of this utility model: 1) Polarization voltage 10.0–48.0V, voltage divider of R1 / R2 / R3 / R4 / R7 / R8 / R9 + ZD1 regulation; 2) Frequency response: 20Hz–20kHz (±0.5dB); 3) Equivalent input noise: ≤1.5μVrms, low-noise transistor + differential input; 4) Power supply rejection ratio ≥90dB@100Hz; 5) Total harmonic distortion ≤0.0001%@1kHz.

[0029] The above are merely preferred embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A microphone gain preamplifier circuit with ultra-low noise floor, characterized in that: The device includes a microphone, an input terminal, a JFET buffer module, a voltage regulator and filter module, a capacitive coupling module, an amplifier module, and an output terminal. The microphone is connected to the input terminal of the input terminal, the output terminal of the input terminal is connected to the input terminal of the JFET buffer module, the output terminal of the JFET buffer module is connected to the input terminals of the voltage regulator and filter module and the capacitive coupling module, the output terminals of the voltage regulator and filter module and the capacitive coupling module are respectively connected to the input terminal of the amplifier module, and the output terminal of the amplifier module is connected to the output terminal.

2. The ultra-low noise floor microphone gain preamplifier circuit according to claim 1, characterized in that: The JFET buffer module includes a field-effect transistor Q3. The gate (G) of the field-effect transistor Q3 is connected to the output terminal of the input terminal. The source (S) of the field-effect transistor Q3 is connected to the voltage regulation and filtering module and the capacitive coupling module, respectively. The drain (D) of the field-effect transistor Q3 is connected to the voltage regulation and filtering module and the capacitive coupling module, respectively.

3. The ultra-low noise floor microphone gain preamplifier circuit according to claim 2, characterized in that: The capacitive coupling module includes capacitor C4, capacitor C5, resistor R5, and resistor R6. One end of capacitor C4 is connected to the source (S) terminal of the field-effect transistor Q3. The other end of capacitor C4 is connected to one end of resistor R5 and the amplification module. The other end of resistor R5 is connected to one end of resistor R6. The other end of resistor R6 is connected to one end of capacitor C5 and the amplification module. The other end of capacitor C5 is connected to the drain (D) terminal of the field-effect transistor Q3.

4. The ultra-low noise floor microphone gain preamplifier circuit according to claim 3, characterized in that: The voltage regulation and filtering module includes resistors R7, R8, R9, and R10, capacitors EC1, EC2, and EC196, and diode ZD1. One end of resistor R10 is connected to the source (S) terminal of the field-effect transistor Q3, and the other end of resistor R10 is connected to one end of capacitor EC2, one end of diode ZD1, one end of capacitor EC1, and one end of capacitor EC196. One end of resistor R9 is connected to the drain (D) terminal of the field-effect transistor Q3, and the other end of resistor R9 is connected to the other end of capacitor EC2 and one end of resistor R8. The other end of resistor R8 is connected to the other end of diode ZD1, the other end of capacitor EC1, and one end of resistor R7. The other end of resistor R7 is connected to the other end of capacitor EC196 and the amplification module.

5. The ultra-low noise floor microphone gain preamplifier circuit according to claim 4, characterized in that: The amplification module includes transistors Q1 and Q2, resistors R1, R2, R3, and R4, and capacitors C1, C2, C3, and C14. The base (B) of transistor Q1 is connected to one end of resistor R5. The collector (C) of transistor Q1 is connected to one end of resistor R3, one end of resistor R4, the collector (C) of transistor Q2, and one end of resistor R6. The emitter (E) of transistor Q1 is connected to one end of capacitor C2, the other end of resistor R3, and one end of resistor R1. The base (B) of transistor Q2... The electrode of the transistor Q2 is connected to one end of the capacitor C5. The emitter of the transistor Q2 is connected to the other end of the resistor R4, one end of the resistor R2, and one end of the capacitor C3. The other ends of the capacitors C2 and C3 are grounded. One end of the capacitor C14 is grounded, and the other end of the capacitor C14 is connected to the other end of the resistor R1. One end of the capacitor C1 is grounded, and the other end of the capacitor C1 is connected to the other end of the resistor R2. The other ends of the resistors R1 and R2 are respectively connected to the output terminal.

6. The ultra-low noise floor microphone gain preamplifier circuit according to claim 5, characterized in that: The transistors Q1 and Q2 are both MMBT5087LT1G.

7. The ultra-low noise floor microphone gain preamplifier circuit according to claim 2, characterized in that: The field-effect transistor Q3 is model J202 SOT-23.

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