CN219697611U

CN219697611U - Low-noise audio amplifying circuit

Info

Publication number: CN219697611U
Application number: CN202320751596.3U
Authority: CN
Inventors: 邓浩; 祝小雅
Original assignee: Iridium Core Technology Shenzhen Co ltd
Current assignee: Iridium Core Technology Shenzhen Co ltd
Priority date: 2023-04-07
Filing date: 2023-04-07
Publication date: 2023-09-15
Anticipated expiration: 2033-04-07

Abstract

The utility model discloses a low-noise audio amplifying circuit, which comprises an input circuit and an amplifying circuit, wherein the input circuit comprises an audio collector, the positive electrode of the audio collector is electrically connected with a 10u capacitor and then is output to the amplifying circuit, the negative electrode of the audio collector is electrically connected with a 100k resistor and then is output to the amplifying circuit, the amplifying circuit comprises an input end Vin connected with the input circuit, the input end Vin is electrically connected with a triode BC109C, the base electrode of the triode BC109C is electrically connected with the input circuit, and the emitter electrode of the triode BC109C is sequentially electrically connected with a 22k resistor and a 2200u capacitor and then is output. The circuit of the present utility model is DC biased such that BD139 and BD140 are at about half the supply voltage to allow maximum output voltage swing. All four transistors are directly coupled, ensuring good low frequency response, temperature and bias voltage variation stability.

Description

Low-noise audio amplifying circuit

Technical Field

The utility model relates to the field of circuits, in particular to a low-noise audio amplifying circuit.

Background

The existing circuit has large noise in audio amplification and other performances are not good, such as a 100W MOSFET power amplifier circuit in the prior art like the audio amplification circuit in FIG. 1. The input stage of the circuit adopts a JEFT input type operational amplifier TL071, and the input impedance is large and the conversion rate is high. VTl and VT3 are complementary constant current source loads of the op amp TL 071. VT4 and VT5 form typical push stage, output stage VT6 and VT7 adopt MOSFET tube, the amplification factor is about 5, the frequency response is 15 Hz-125 kHz at full power, and output noise is-95 dB.

Disclosure of Invention

In order to achieve the above purpose, the present utility model provides the following technical solutions:

the utility model provides a low noise audio amplifier circuit, includes input circuit and amplifier circuit, input circuit includes the audio collector, output to amplifier circuit after the positive pole electricity of audio collector connects a 10u electric capacity, output to amplifier circuit after the resistance of 100k is connected to the negative pole electricity of audio collector, amplifier circuit includes the input Vin who is connected with input circuit, a triode BC109C is connected to input Vin electricity, triode BC 109C's base is connected with the input circuit electricity, triode BC 109C's projecting pole is the electric resistance of 22k, the output after 2200u electric capacity of connecting gradually.

Further, the input end Vin is further electrically connected with two resistors 27k and one resistor 12k in sequence and then is electrically connected with the collector of the triode BC109C, a branch circuit is arranged between the two resistors 27k and is electrically connected with a capacitor 470u, and the negative electrode of the capacitor 470u is grounded.

Further, the collector of the triode BC109C is electrically connected to the base of a triode 2N3906, the emitter of the triode 2N3906 is electrically connected to one end of a resistor 330k, the other end of the resistor 330k is electrically connected to one of the resistor 27k and the resistor 12k, and the collector of the triode 2N3906 is electrically connected to two diodes, a sliding resistor and a resistor 1.8k in sequence and then grounded.

Further, the collector of the triode 2N3906 is further electrically connected to the base of a triode BD139, the collector of the triode BD139 is coupled to the input end Vin, the emitter of the triode BD139 is electrically connected to the emitter of a triode BD140 after being electrically connected to two resistors of 1k, the collector of the triode BD140 is grounded, and the base of the triode BD140 is electrically connected to the sliding resistor and the resistor of 1.8k respectively.

Further, the output end of the amplifying circuit is also electrically connected with a resistor and then grounded.

Compared with the prior art, the utility model has the following beneficial effects:

the circuit of the present utility model is DC biased such that BD139 and BD140 are at about half the supply voltage to allow maximum output voltage swing. All four transistors are directly coupled, ensuring good low frequency response, temperature and bias variation stability, and low noise, BC109C and 2N3906 operate in a common emitter, which alone would provide very high open loop gain, output BD139/140 pair operating in the emitter follower, meeting the requirements for driving low impact speakers.

Drawings

FIG. 1 is a schematic diagram of a circuit in the background of the utility model;

FIG. 2 is a schematic diagram of a portion of the circuit of the present utility model, specifically, a schematic diagram of the input circuit;

fig. 3 is a schematic circuit diagram of a portion of the present utility model, specifically, an amplifying circuit.

Detailed Description

The following description of the embodiments of the present utility model will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present utility model, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without making any inventive effort, are intended to be within the scope of the utility model.

The utility model provides a low-noise audio amplifying circuit, which is shown in fig. 2-3, and comprises an input circuit and an amplifying circuit, wherein the input circuit comprises an audio collector, the anode of the audio collector is electrically connected with a 10u capacitor and then is output to the amplifying circuit, the cathode of the audio collector is electrically connected with a 100k resistor and then is output to the amplifying circuit, the amplifying circuit comprises an input end Vin connected with the input circuit, the input end Vin is electrically connected with a triode BC109C, the base electrode of the triode BC109C is electrically connected with the input circuit, and the emitter of the triode BC109C is sequentially electrically connected with a 22k resistor and a 2200u capacitor and then is output. The circuit of the present utility model is DC biased such that BD139 and BD140 are at about half the supply voltage to allow maximum output voltage swing. All four transistors are directly coupled, ensuring good low frequency response, temperature and bias variation stability, and low noise, BC109C and 2N3906 operate in a common emitter, which alone would provide very high open loop gain, output BD139/140 pair operating in the emitter follower, meeting the requirements for driving low impact speakers.

In a preferred embodiment, the input terminal Vin is further electrically connected to two resistors 27k, one resistor 12k and then electrically connected to the collector of the triode BC109C, a branch circuit is disposed between the two resistors 27k and electrically connected to a capacitor 470u, and the negative electrode of the capacitor 470u is grounded.

In a preferred embodiment, the collector of the triode BC109C is electrically connected to the base of a triode 2N3906, the emitter of the triode 2N3906 is electrically connected to one end of a resistor 330k, the other end of the resistor 330k is electrically connected to one of the resistor 27k and the resistor 12k, and the collector of the triode 2N3906 is sequentially electrically connected to two diodes, a sliding resistor and a resistor 1.8k and then grounded.

In a preferred embodiment, the collector of the triode 2N3906 is further electrically connected to the base of a triode BD139, the collector of the triode BD139 is coupled to the input terminal Vin, the emitter of the triode BD139 is electrically connected to the emitter of a triode BD140 after being electrically connected to two resistors of 1k, the collector of the triode BD140 is grounded, and the base of the triode BD140 is electrically connected to the sliding resistor and the resistor of 1.8k respectively.

In a preferred embodiment, the output end of the amplifying circuit is further electrically connected to a resistor and then grounded.

In a specific embodiment, the utility model provides a low-noise audio amplifying circuit, as shown in fig. 2-3, comprising an input circuit and an amplifying circuit, wherein the input circuit comprises an audio collector, the positive electrode of the audio collector is electrically connected with a 10u capacitor and then output to the amplifying circuit, the negative electrode of the audio collector is electrically connected with a 100k resistor and then output to the amplifying circuit, the amplifying circuit comprises an input end Vin connected with the input circuit, the input end Vin is electrically connected with a triode BC109C, the base electrode of the triode BC109C is electrically connected with the input circuit, and the emitter electrode of the triode BC109C is sequentially electrically connected with a 22k resistor and a 2200u capacitor and then output. The input end Vin is also electrically connected with two resistors 27k and one resistor 12k in sequence and then is electrically connected with the collector of the triode BC109C, a branch circuit is arranged between the two resistors 27k and is electrically connected with a capacitor 470u, and the negative electrode of the capacitor 470u is grounded. The collector of the triode BC109C is electrically connected with the base of a triode 2N3906, the emitter of the triode 2N3906 is electrically connected with one end of a resistor 330k, the other end of the resistor 330k is respectively electrically connected with one of a resistor 27k and a resistor 12k, and the collector of the triode 2N3906 is sequentially electrically connected with two diodes, a sliding resistor and a resistor 1.8k and then grounded. The collector of the triode 2N3906 is further electrically connected with the base of a triode BD139, the collector of the triode BD139 is coupled with the input end Vin, the emitter of the triode BD139 is electrically connected with the emitter of a triode BD140 after being electrically connected with two resistors of 1k, the collector of the triode BD140 is grounded, and the base of the triode BD140 is electrically connected with the sliding resistor and the resistor of 1.8k respectively. The output end of the amplifying circuit is also electrically connected with a resistor and then grounded.

Although embodiments of the present utility model have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made therein without departing from the principles and spirit of the utility model, the scope of which is defined in the appended claims and their equivalents.

Claims

1. The utility model provides a low noise audio amplifier circuit, its characterized in that includes input circuit and amplifier circuit, input circuit includes the audio collector, output to amplifier circuit after the positive pole electricity of audio collector connects a 10u electric capacity, output to amplifier circuit after the negative pole electricity of audio collector connects a 100k resistance, amplifier circuit includes the input Vin who is connected with input circuit, input Vin electricity is connected a triode BC109C, triode BC 109C's base is connected with input circuit electricity, triode BC 109C's projecting pole is the electric output after 22k resistance, a 220u electric capacity of connecting in proper order.

2. The low noise audio amplifier circuit of claim 1, wherein the input terminal Vin is further electrically connected to two resistors 27k, one resistor 12k is electrically connected to the collector of the triode BC109C, a capacitor 470u is electrically connected between the two resistors 27k, and the negative electrode of the capacitor 470u is grounded.

3. The low noise audio amplifier circuit of claim 2, wherein the collector of the triode BC109C is electrically connected to the base of a triode 2N3906, the emitter of the triode 2N3906 is electrically connected to one end of a 330k resistor, the other end of the 330k resistor is electrically connected to one of the 27k resistor and the 12k resistor, respectively, and the collector of the triode 2N3906 is electrically connected to two diodes, a sliding resistor and a 1.8k resistor in turn and then grounded.

4. A low noise audio amplifier circuit according to claim 3, wherein the collector of the triode 2N3906 is further electrically connected to the base of a triode BD139, the collector of the triode BD139 is coupled to the input Vin, the emitter of the triode BD139 is electrically connected to the two resistors of 1k and then to the emitter of a triode BD140, the collector of the triode BD140 is grounded, and the base of the triode BD140 is electrically connected to the sliding resistor and the resistor of 1.8k, respectively.

5. The low noise audio amplifier circuit of claim 4, wherein the output of the amplifier circuit is further electrically coupled to a resistor and then to ground.