阅读说明：本技术 一种电压电流双反馈放大电路、功率放大器和耳机 (Voltage and current double-feedback amplifying circuit, power amplifier and earphone ) 是由 臧厚宁 于 2020-05-28 设计创作，主要内容包括：本发明涉及一种电压电流双反馈放大电路、功率放大器和耳机,通过采用正周期放大模块、负周期放大模块构成推挽式放大电路,分别对音频信号的正周期信号和负周期信号分别逐级进行的电压、电流和功率的放大使其能够满足信号放大的需求,同时通过反馈模块中的切换开关,对放大电路中电压反馈和电流反馈的形式进行选择,使用户可根据自己的喜好和音频的特征选择,合适的反馈形式对音频信号进行放大,实现了在同一放大电路中的电压电流的双反馈,拓展了放大电路的使用宽度,可使用户获得最佳的使用效果,为用户提供了便利。(The invention relates to a voltage and current double feedback amplifying circuit, a power amplifier and an earphone.A push-pull amplifying circuit is formed by adopting a positive period amplifying module and a negative period amplifying module, the positive period signal and the negative period signal of an audio signal are respectively amplified by voltage, current and power step by step to meet the requirement of signal amplification, and simultaneously, the forms of voltage feedback and current feedback in the amplifying circuit are selected by a change-over switch in the feedback module, so that a user can select according to own favor and the characteristics of audio, and the audio signal is amplified in a proper feedback form.)

1. A voltage-current dual feedback amplifier circuit, comprising: the positive period amplification module, the negative period amplification module and the feedback module;

the positive period amplification module comprises: a first amplifying circuit, a second amplifying circuit, a third amplifying circuit and a fourth amplifying circuit;

the negative period amplification module includes: a fifth amplification circuit, a sixth amplification circuit, a seventh amplification circuit, and an eighth amplification circuit;

the input point of the control end of the first amplifying circuit and the input point of the control end of the fifth amplifying circuit after connection is connected with an audio signal;

the input end of the first amplifying circuit is connected with the positive pole of the power supply, and the output end of the first amplifying circuit is connected with the negative pole of the power supply and is used for carrying out preliminary voltage amplification on the positive periodic signal of the audio signal;

the control end of the second amplifying circuit is connected with the output end of the first amplifying circuit, the input end of the second amplifying circuit is connected with the positive electrode of the power supply, and the output end of the second amplifying circuit is connected with the negative electrode of the power supply and is used for further amplifying the voltage of the positive periodic signal;

the control end of the third amplifying circuit is connected with the output end of the second amplifying circuit, the input end of the third amplifying circuit is grounded through a first grounding resistor, and the output end of the third amplifying circuit is connected with the negative electrode of a power supply and used for carrying out current amplification on the positive periodic signal;

the control end of the fourth amplifying circuit is connected with the input end of the third amplifying circuit, the input end of the fourth amplifying circuit is connected with an output point connected with a load, and the output end of the fourth amplifying circuit is connected with the negative electrode of a power supply and used for amplifying the power of the positive periodic signal and then outputting the amplified positive periodic signal;

the input end of the fifth amplifying circuit is connected with the positive electrode of the power supply, and the output end of the fifth amplifying circuit is connected with the negative electrode of the power supply and is used for carrying out preliminary voltage amplification on the negative periodic signal of the audio signal;

the control end of the sixth amplifying circuit is connected with the input end of the fifth amplifying circuit, the input end of the sixth amplifying circuit is connected with the positive electrode of the power supply, and the output end of the sixth amplifying circuit is connected with the negative electrode of the power supply and is used for further voltage amplification of the negative periodic signal;

the control end of the seventh amplifying circuit is connected with the input end of the sixth amplifying circuit, the output end of the seventh amplifying circuit is grounded through a second grounding resistor, and the input end of the seventh amplifying circuit is connected with the positive electrode of a power supply and used for carrying out current amplification on a negative periodic signal;

the control end of the eighth amplifying circuit is connected with the output end of the seventh amplifying circuit, the output end of the eighth amplifying circuit is connected with an output point connected with a load, and the input end of the eighth amplifying circuit is connected with the positive electrode of a power supply and used for amplifying the power of the positive periodic signal and then outputting the amplified positive periodic signal;

the feedback module includes: the circuit comprises a first voltage feedback circuit, a second voltage feedback circuit, a first current feedback circuit, a second current feedback circuit, a selector switch and a feedback resistance circuit;

a first end of the change-over switch is connected with the output point, a second end of the change-over switch is connected with an input end of the first voltage feedback circuit and an input end of the second voltage feedback circuit, a first output end of the first voltage feedback circuit is connected with an input end of the second amplifying circuit, a second output end of the first voltage feedback circuit is grounded, a first output end of the second voltage feedback circuit is connected with an output end of the sixth amplifying circuit, a second output end of the second voltage feedback circuit is grounded, and voltage feedback is performed after the first end and the second end of the change-over switch are communicated;

the third end of the change-over switch is connected with the midpoint of the feedback resistance circuit, the input end of the feedback resistance circuit is connected with the output point, and the output end of the feedback resistance circuit is grounded; the fourth end of the change-over switch is connected with the input end of the first current feedback circuit and the input end of the second current feedback circuit, and the output end of the first current feedback circuit is connected with the front ends of the two output ends of the first voltage feedback circuit; the output end of the second current feedback circuit is connected with the front ends of the two output ends of the second voltage feedback circuit, and current feedback is carried out after the third end and the fourth end of the change-over switch are communicated.

2. The voltage-current dual feedback amplification circuit of claim 1, further comprising: and the input end of the coupling circuit is connected with the audio signal and used for inputting the audio signal, and the output end of the coupling circuit is connected with the input point and used for inputting the coupled audio signal.

3. The voltage-current dual feedback amplification circuit of claim 1, further comprising: and the two input ends of the zero setting circuit are correspondingly connected with the positive electrode of the power supply and the negative electrode of the power supply, and the adjustable output end of the zero setting circuit is connected with the input point and is used for adjusting the voltage of the output end of the eighth amplifying circuit and the input end of the fourth amplifying circuit to the ground to be 0V.

4. The voltage-current dual feedback amplification circuit of claim 1, further comprising: a voltage regulation circuit, the voltage regulation circuit comprising: the first voltage regulating circuit is arranged between the input end of the first amplifying circuit and the positive electrode of the power supply and is used for reducing voltage; the second voltage regulating circuit is arranged between the output end of the fifth amplifying circuit and the negative electrode of the power supply and used for increasing voltage.

5. The voltage-current double feedback amplification circuit according to claim 1, further comprising a constant current circuit, the constant current circuit comprising: the first constant current circuit is arranged between the output end of the first amplifying circuit and the negative electrode of the power supply and is used for stabilizing and limiting current; the second constant current circuit is arranged between the input end of the fifth amplifying circuit and the positive electrode of the power supply and used for stabilizing current and limiting current.

6. The voltage-current dual feedback amplification circuit of claim 1, further comprising: and the isolation circuit is arranged between the output point and the load and is used for isolating the output direct current signal.

7. The voltage-current dual feedback amplifier circuit according to claim 1, wherein the first voltage feedback circuit and the second voltage feedback circuit are identical in structure and each comprises: the first resistor and the capacitor are connected in parallel and then connected in series with the second resistor, the input end of the parallel circuit is connected with the second end of the change-over switch, the output end of the second resistor and the output end of the parallel circuit are connected and then grounded, and the output end of the parallel circuit is further connected with the input end of the second amplifying circuit or the output end of the sixth amplifying circuit.

8. The voltage-current dual feedback amplifier circuit as claimed in claim 7, wherein the feedback resistor circuit comprises a third resistor and a fourth resistor, the third resistor and the fourth resistor are connected in series, one end of the series circuit is connected to the output point, the other end of the series circuit is connected to ground, and a third end of the switch is connected to a connection point of the third resistor and the fourth resistor; the first current feedback circuit and the second current feedback circuit are of the same structure and comprise fifth resistors, one end of each fifth resistor is connected with the fourth end of the corresponding change-over switch, and the fifth resistors are connected with the output ends of the parallel circuits.

9. A power amplifier comprising the voltage-current dual feedback amplification circuit of any one of claims 1 to 8.

10. An earphone, characterized by comprising a voltage-current dual feedback amplification circuit according to any one of claims 1 to 8.

Technical Field

The invention belongs to the technical field of power amplifier circuits, and particularly relates to a voltage and current double-feedback amplifying circuit, a power amplifier and an earphone.

Background

The negative feedback circuit adopted by the existing audio amplification circuit mainly comprises three types: the first is a voltage negative feedback circuit, the second is a current negative feedback circuit, and the third is a negative feedback circuit without a large loop. The first is most commonly used). The third feedback circuit is not commonly used because the third circuit operation is not very stable in operation. The main application be two kinds of preceding voltage negative feedback and current negative feedback, voltage negative feedback circuit and current negative feedback circuit respectively have its advantage and shortcoming, the feedback circuit that products such as current earphones adopted either be voltage negative feedback circuit, or be current negative feedback circuit, have different tone quality effects, the user can only satisfy through the mode of changing the product for obtaining different experience, not only increase the cost of purchase but also change also very inconvenience.

Disclosure of Invention

In order to solve the problems of single feedback form of the amplifying circuit, inconvenience for replacement and inconvenience for users in the prior art, the invention provides the voltage and current double-feedback amplifying circuit, the power amplifier and the earphone, which have the characteristics of realizing double feedback of voltage and current in the same amplifying circuit, expanding the use width of the amplifying circuit, enabling users to obtain the optimal use effect, providing convenience for users and the like.

The technical scheme adopted by the invention is as follows:

a voltage-current dual feedback amplification circuit, comprising: the positive period amplification module, the negative period amplification module and the feedback module;

the positive period amplification module comprises: a first amplifying circuit, a second amplifying circuit, a third amplifying circuit and a fourth amplifying circuit;

the negative period amplification module includes: a fifth amplification circuit, a sixth amplification circuit, a seventh amplification circuit, and an eighth amplification circuit;

the input point of the control end of the first amplifying circuit and the input point of the control end of the fifth amplifying circuit after connection is connected with an audio signal;

the input end of the first amplifying circuit is connected with the positive pole of the power supply, and the output end of the first amplifying circuit is connected with the negative pole of the power supply and is used for carrying out preliminary voltage amplification on the positive periodic signal of the audio signal;

the control end of the second amplifying circuit is connected with the output end of the first amplifying circuit, the input end of the second amplifying circuit is connected with the positive electrode of the power supply, and the output end of the second amplifying circuit is connected with the negative electrode of the power supply and is used for further amplifying the voltage of the positive periodic signal;

the control end of the third amplifying circuit is connected with the output end of the second amplifying circuit, the input end of the third amplifying circuit is grounded through a first grounding resistor, and the output end of the third amplifying circuit is connected with the negative electrode of a power supply and used for carrying out current amplification on the positive periodic signal;

the control end of the fourth amplifying circuit is connected with the input end of the third amplifying circuit, the input end of the fourth amplifying circuit is connected with an output point connected with a load, and the output end of the fourth amplifying circuit is connected with the negative electrode of a power supply and used for amplifying the power of the positive periodic signal and then outputting the amplified positive periodic signal;

the input end of the fifth amplifying circuit is connected with the positive electrode of the power supply, and the output end of the fifth amplifying circuit is connected with the negative electrode of the power supply and is used for carrying out preliminary voltage amplification on the negative periodic signal of the audio signal;

the control end of the sixth amplifying circuit is connected with the input end of the fifth amplifying circuit, the input end of the sixth amplifying circuit is connected with the positive electrode of the power supply, and the output end of the sixth amplifying circuit is connected with the negative electrode of the power supply and is used for further voltage amplification of the negative periodic signal;

the control end of the seventh amplifying circuit is connected with the input end of the sixth amplifying circuit, the output end of the seventh amplifying circuit is grounded through a second grounding resistor, and the input end of the seventh amplifying circuit is connected with the positive electrode of a power supply and used for carrying out current amplification on a negative periodic signal;

the control end of the eighth amplifying circuit is connected with the output end of the seventh amplifying circuit, the output end of the eighth amplifying circuit is connected with an output point connected with a load, and the input end of the eighth amplifying circuit is connected with the positive electrode of a power supply and used for amplifying the power of the positive periodic signal and then outputting the amplified positive periodic signal;

the feedback module includes: the circuit comprises a first voltage feedback circuit, a second voltage feedback circuit, a first current feedback circuit, a second current feedback circuit, a selector switch and a feedback resistance circuit;

a first end of the change-over switch is connected with the output point, a second end of the change-over switch is connected with an input end of the first voltage feedback circuit and an input end of the second voltage feedback circuit, a first output end of the first voltage feedback circuit is connected with an input end of the second amplifying circuit, a second output end of the first voltage feedback circuit is grounded, a first output end of the second voltage feedback circuit is connected with an output end of the sixth amplifying circuit, a second output end of the second voltage feedback circuit is grounded, and voltage feedback is performed after the first end and the second end of the change-over switch are communicated;

the third end of the change-over switch is connected with the midpoint of the feedback resistance circuit, the input end of the feedback resistance circuit is connected with the output point, and the output end of the feedback resistance circuit is grounded; the fourth end of the change-over switch is connected with the input end of the first current feedback circuit and the input end of the second current feedback circuit, and the output end of the first current feedback circuit is connected with the front ends of the two output ends of the first voltage feedback circuit; the output end of the second current feedback circuit is connected with the front ends of the two output ends of the second voltage feedback circuit, and current feedback is carried out after the third end and the fourth end of the change-over switch are communicated.

Further, the voltage-current dual feedback amplifying circuit further includes: and the input end of the coupling circuit is connected with the audio signal and used for inputting the audio signal, and the output end of the coupling circuit is connected with the input point and used for inputting the coupled audio signal.

Further, the voltage-current dual feedback amplifying circuit further includes: and the two input ends of the zero setting circuit are correspondingly connected with the positive electrode of the power supply and the negative electrode of the power supply, and the adjustable output end of the zero setting circuit is connected with the input point and is used for adjusting the voltage of the output end of the eighth amplifying circuit and the input end of the fourth amplifying circuit to the ground to be 0V.

Further, the voltage-current dual feedback amplifying circuit further includes: a voltage regulation circuit, the voltage regulation circuit comprising: the first voltage regulating circuit is arranged between the input end of the first amplifying circuit and the positive electrode of the power supply and is used for reducing voltage; the second voltage regulating circuit is arranged between the output end of the fifth amplifying circuit and the negative electrode of the power supply and used for increasing voltage.

Further, the voltage and current double-feedback amplifying circuit further comprises a constant current circuit, and the constant current circuit comprises: the first constant current circuit is arranged between the output end of the first amplifying circuit and the negative electrode of the power supply and is used for stabilizing and limiting current; the second constant current circuit is arranged between the input end of the fifth amplifying circuit and the positive electrode of the power supply and used for stabilizing current and limiting current.

Further, the voltage-current dual feedback amplifying circuit further includes: and the isolation circuit is arranged between the output point and the load and is used for isolating the output direct current signal.

Further, the first voltage feedback circuit and the second voltage feedback circuit have the same structure and each include: the first resistor and the capacitor are connected in parallel and then connected in series with the second resistor, the input end of the parallel circuit is connected with the second end of the change-over switch, the output end of the second resistor and the output end of the parallel circuit are connected and then grounded, and the output end of the parallel circuit is further connected with the input end of the second amplifying circuit or the output end of the sixth amplifying circuit.

Furthermore, the feedback resistance circuit comprises a third resistor and a fourth resistor, the third resistor and the fourth resistor are connected in series, one end of the series circuit is connected with the output point, the other end of the series circuit is grounded, and a third end of the change-over switch is connected with a connection point of the third resistor and the fourth resistor; the first current feedback circuit and the second current feedback circuit are of the same structure and comprise fifth resistors, one end of each fifth resistor is connected with the fourth end of the corresponding change-over switch, and the fifth resistors are connected with the output ends of the parallel circuits.

According to the specific embodiment of the invention, the power amplifier comprises the voltage-current dual feedback amplifying circuit.

According to the embodiment of the invention, the earphone comprises the voltage-current dual-feedback amplifying circuit.

The invention has the beneficial effects that: the positive period amplification module and the negative period amplification module form a push-pull type amplification circuit, voltage, current and power amplification is respectively carried out on a positive period signal and a negative period signal of an audio signal step by step, so that the requirements of signal amplification can be met, meanwhile, the forms of voltage feedback and current feedback in the amplification circuit are selected through a change-over switch in the feedback module, a user can select the audio signal according to the preference and the characteristics of audio, the audio signal is amplified in a proper feedback form, double feedback of voltage and current in the same amplification circuit is realized, the use width of the amplification circuit is expanded, the user can obtain the best use effect, and convenience is provided for the user.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a schematic diagram of a voltage-current dual feedback amplification circuit provided in accordance with an exemplary embodiment;

FIG. 2 is another schematic diagram of a voltage-current dual feedback amplification circuit provided in accordance with an exemplary embodiment;

fig. 3 is a circuit diagram of a voltage-current dual feedback amplification circuit provided in accordance with an example embodiment.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be described in detail below. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the examples given herein without any inventive step, are within the scope of the present invention.

Referring to fig. 1, an embodiment of the present invention provides a voltage-current dual feedback amplifier circuit for amplifying an audio signal, including: the positive period amplification module, the negative period amplification module and the feedback module;

the positive period amplification module includes: a first amplifying circuit, a second amplifying circuit, a third amplifying circuit and a fourth amplifying circuit;

the negative period amplification module includes: a fifth amplification circuit, a sixth amplification circuit, a seventh amplification circuit, and an eighth amplification circuit;

the input point of the control end of the first amplifying circuit and the input point of the control end of the fifth amplifying circuit after connection is connected with the audio signal; the first amplifying circuit and the fifth amplifying circuit alternately work in a power amplifier with a push-pull type in which the positive half period and the negative half period of an input audio signal are in a push-pull type.

The input end of the first amplifying circuit is connected with the positive pole of the power supply, and the output end of the first amplifying circuit is connected with the negative pole of the power supply and is used for carrying out preliminary voltage amplification on the positive periodic signal of the audio signal;

the control end of the second amplifying circuit is connected with the output end of the first amplifying circuit, the input end of the second amplifying circuit is connected with the positive electrode of the power supply, and the output end of the second amplifying circuit is connected with the negative electrode of the power supply and is used for further amplifying the voltage of the positive periodic signal;

the control end of the third amplifying circuit is connected with the output end of the second amplifying circuit, the input end of the third amplifying circuit is grounded through a first grounding resistor, and the output end of the third amplifying circuit is connected with the negative electrode of a power supply and used for carrying out current amplification on the positive periodic signal;

the control end of the fourth amplifying circuit is connected with the input end of the third amplifying circuit, the input end of the fourth amplifying circuit is connected with the output point of the load connection, and the output end of the fourth amplifying circuit is connected with the negative electrode of the power supply and used for outputting the positive periodic signal after power amplification;

the input end of the fifth amplifying circuit is connected with the positive electrode of the power supply, and the output end of the fifth amplifying circuit is connected with the negative electrode of the power supply and is used for carrying out preliminary voltage amplification on the negative periodic signal of the audio signal;

the control end of the sixth amplifying circuit is connected with the input end of the fifth amplifying circuit, the input end of the sixth amplifying circuit is connected with the positive electrode of the power supply, and the output end of the sixth amplifying circuit is connected with the negative electrode of the power supply and is used for further amplifying the voltage of the negative periodic signal;

the control end of the seventh amplifying circuit is connected with the input end of the sixth amplifying circuit, the output end of the seventh amplifying circuit is grounded through a second grounding resistor, and the input end of the seventh amplifying circuit is connected with the positive electrode of the power supply and used for carrying out current amplification on the negative periodic signal;

the control end of the eighth amplifying circuit is connected with the output end of the seventh amplifying circuit, the output end of the eighth amplifying circuit is connected with an output point connected with a load, and the input end of the eighth amplifying circuit is connected with the positive electrode of a power supply and used for amplifying the power of the positive periodic signal and then outputting the amplified positive periodic signal;

the feedback module comprises: the circuit comprises a first voltage feedback circuit, a second voltage feedback circuit, a first current feedback circuit, a second current feedback circuit, a selector switch and a feedback resistance circuit;

the first end of the change-over switch is connected with the output point, the second end of the change-over switch is connected with the input end of the first voltage feedback circuit and the input end of the second voltage feedback circuit, the first output end of the first voltage feedback circuit is connected with the input end of the second amplifying circuit, the second output end of the first voltage feedback circuit is grounded, the first output end of the second voltage feedback circuit is connected with the output end of the sixth amplifying circuit, the second output end of the second voltage feedback circuit is grounded, and voltage feedback is carried out after the first end and the second end of the change-over switch are communicated;

the third end of the switch is connected with the midpoint of the feedback resistance circuit, the input end of the feedback resistance circuit is connected with the output point, and the output end of the feedback resistance circuit is grounded; the fourth end of the change-over switch is connected with the input end of the first current feedback circuit and the input end of the second current feedback circuit, and the output end of the first current feedback circuit is connected with the front ends of the two output ends of the first voltage feedback circuit; the output end of the second current feedback circuit is connected with the front ends of the two output ends of the second voltage feedback circuit, and current feedback is carried out after the third end and the fourth end of the change-over switch are communicated.

Specifically, the push-pull amplification circuit is used for alternately amplifying positive and negative periodic signals of an audio signal, so that the symmetrically designed positive periodic amplification module amplifies the positive periodic signal in the audio signal, the negative periodic amplification module is used for amplifying the audio signal in the negative period, the first amplification circuit and the fifth amplification circuit adopt transistors with similar parameters but opposite conduction polarities, for example, the first amplification circuit adopts an NPN type triode, the fifth amplification circuit adopts a PNP type triode, the second amplification circuit corresponding to the push-pull preliminary amplification adopts a PNP type triode, the third amplification circuit adopts a PNP type triode, and the fourth amplification circuit adopts an NPN type triode; the sixth amplifying circuit adopts an NPN type triode, the seventh amplifying circuit adopts an NPN type triode, and the eighth amplifying circuit adopts a PNP type triode; the first amplifying circuit and the fifth amplifying circuit correspondingly form a first-stage amplifying circuit, the second amplifying circuit and the sixth amplifying circuit correspondingly form a second-stage amplifying circuit, the third amplifying circuit and the seventh amplifying circuit correspondingly form a third-stage amplifying circuit, the fourth amplifying circuit and the eighth amplifying circuit correspondingly form a fourth-stage amplifying circuit, the amplification is performed step by step, a feedback module and a change-over switch are added at the tail end, the selection of voltage and current feedback can be performed respectively, the width of audio amplification is expanded, different feedback forms can be selected according to different conditions, convenience is provided for users, and the users can obtain better effects.

The control end, the input end and the output end of the amplifying circuit correspond to three pins of the triode respectively, wherein the control end is a base electrode of the triode, the input end and the output end are relative to the flow direction of current of a collector electrode and an emitter electrode of the triode, the end where the current flows in is the input end, and the end where the current flows out is the output end.

Referring to fig. 2, in some embodiments of the invention, the method further includes: and the input end of the coupling circuit is connected with the audio signal for inputting the audio signal, and the output end and the input point of the coupling circuit are connected with the input of the coupled audio signal.

Further comprising: and two input ends of the zero setting circuit are correspondingly connected with the positive electrode of the power supply and the negative electrode of the power supply, and an adjustable output end of the zero setting circuit is connected with an input point and is used for adjusting the voltage of the output end of the eighth amplifying circuit and the voltage of the input end of the fourth amplifying circuit to be 0V to the ground.

Further comprising: the regulator circuit, the regulator circuit includes: the first voltage regulating circuit is arranged between the input end of the first amplifying circuit and the positive electrode of the power supply and is used for reducing voltage; the second voltage regulating circuit is arranged between the output end of the fifth amplifying circuit and the negative electrode of the power supply and used for boosting voltage.

Still include the constant current circuit, the constant current circuit includes: the first constant current circuit is arranged between the output end of the first amplifying circuit and the negative electrode of the power supply and is used for stabilizing and limiting current; the second constant current circuit is arranged between the input end of the fifth amplifying circuit and the positive electrode of the power supply and used for stabilizing current and limiting current.

Further comprising: and the isolation circuit is arranged between the output point and the load and is used for isolating the output direct current signal.

The first voltage feedback circuit and the second voltage feedback circuit are of the same structure and comprise: the first resistor, the second resistor and the capacitor are connected in parallel and then connected in series with the second resistor, the input end of the parallel circuit is connected with the second end of the change-over switch, the output end of the second resistor and the output end of the parallel circuit are connected and then grounded, and the output end of the parallel circuit is also connected with the input end of the second amplifying circuit or the output end of the sixth amplifying circuit.

The feedback resistance circuit comprises a third resistor and a fourth resistor, the third resistor and the fourth resistor are connected in series, one end of the series circuit is connected with the output point, the other end of the series circuit is grounded, and the third end of the change-over switch is connected with the connection point of the third resistor and the fourth resistor; the first current feedback circuit and the second current feedback circuit are of the same structure and respectively comprise a fifth resistor, one end of the fifth resistor is connected with the fourth end of the change-over switch, and the fifth resistor is connected with the output end of the parallel circuit.

As a specific implementation manner of the above embodiment, refer to a circuit diagram of a voltage-current dual feedback amplification circuit shown in fig. 3:

the positive period amplification module is formed by taking Q2, Q4, Q6 and Q8 as amplifiers, and the negative period amplification module is formed by taking Q1, Q3, Q5 and Q7 as amplifiers; q1 and Q2 form a first-stage amplifying circuit, Q3 and Q4 form a second-stage amplifying circuit relatively, Q5 and Q6 form a third-stage amplifying circuit relatively, and Q7 and Q8 form a fourth-stage amplifying circuit relatively;

after the audio signal is accessed from an interface, the audio signal is firstly coupled to the base electrodes of Q1 and Q2 through a coupling circuit formed by C1, C2 and R1 to be subjected to initial amplification of the signal, two 3.3u nonpolar capacitors of C1 and C2 are selected to be coupled in parallel, and compared with the mode that one 6.6u capacitor is selected and not easily bought in the market, the audio signal is easier to obtain and has higher cost performance;

the zero setting circuit adopts a symmetrical power supply design, a voltage drop is generated on a trimming resistor P1, the voltage of a center tap is changed in a small range by adjusting the position of P1, because the collectors of the amplifiers from Q1 to Q8 are all in direct current coupling, and because the center tap of P1 is connected with bases of Q1 and Q2, the voltage of the collectors of Q7 and Q8 can be changed by changing the center voltage of P1 through one-stage transmission, so that the ground is 0V, which is called as '0 adjustment', and the power amplification is more accurate;

the preliminarily amplified audio signals are output by emitters of Q1 and Q2, transmitted to Q3 and Q4 for further voltage amplification, correspondingly enter bases of Q5 and Q6 through R10 and R11 for current amplification, are output by a transmitter, are amplified in power through R16 and R17, and are output by a collector. Here the first ground resistance is R15 and the second ground resistance is R14.

The output signal is output to the load through a direct current blocking capacitor C8 (an isolation circuit); the other path enters a feedback module, wherein R13, R17 and C7 form a first voltage feedback circuit, R12, R20 and C6 form a second voltage feedback circuit, and K1-1 is used for switching control of a first end and a second end of a change-over switch; r24 and R25 form a feedback resistor circuit, R19 is a first current feedback circuit, R18 is a second current feedback circuit, and K1-2 is used for switching control of a third end and a fourth end of the change-over switch;

when K1-1 is closed and K1-2 is opened, the feedback network of the feedback module consists of a first voltage feedback circuit formed by R13, R17 and C7 and a second voltage feedback circuit formed by R12, R20 and C6. The negative feedback signal is taken from the collectors of Q7 and Q8 and is a voltage signal, so for voltage negative feedback, there are three main roles: 1. the amplification factor (gain) is adjusted. The amplification factor of the positive and negative signals is 1 ten R20/R12-1 ten R21/R13, so that the amplification amount can be changed by changing the values of R20, R12, R21 and R13, and the amplification circuit has proper gain. Because positive and negative periodic signals of the audio signal are respectively amplified, R20 and R21 are required to be the same, R12 and R13 are also required, otherwise, positive and negative half-cycle waveforms of the alternating current signal are asymmetric; 2. widening the frequency band, and reducing distortion, widening the frequency band, stabilizing the amplification amount and the like according to the related theoretical negative feedback of the electronic circuit); 3. distortion is reduced, and circuit performance is improved.

When K1-1 is opened (open circuit state), K1-2 is closed (short circuit state), a feedback signal network is composed of R24, R25, R18, R19 and the like, a feedback signal is taken from the upper end of R25, when signal current flows through R24 and R25, a voltage drop is generated on R25, the voltage drop is fed back to an input end by R18 and R19 to generate negative feedback effect, the feedback signal is generated by the signal current and is called current feedback, the circuit gain is equal to R24/R25, and therefore the amplification factor can be changed by changing the resistance values of R24 and R25.

The voltage and current double feedback is realized through ingenious design. Only one switch is used, the function of voltage and current double feedback is realized, the use width of the audio amplifier is expanded, and a user can select different feedback modes according to the characteristics of the earphone or the listening habits of the user. Thereby obtaining the best effect.

The +/-35V power supply enables two voltage stabilizing poles of D1 and D2 to have a proper working current through the action of current limiting resistors R4 and R5, so that D1 and D2 are prevented from burning out, an amplifier power supply composed of a first stage Q1 and Q2 is reduced to +/-15V for supplying power, and C9C11 and C10C12 are further filtered to reduce noise and improve the signal-to-noise ratio.

The emitters of Q1 and Q2 are respectively provided with a first constant current circuit and a second constant current circuit, CRD1 and CRD2 are constant current diodes, the working currents of Q1 and Q2 are between 1mA and 2mA by selecting different types of constant current diodes, the amplifying circuit selects 1.5mA, the constant current tubes with different constant current currents can change the sound density of the amplifier, so that the tone is finely adjusted, and R2 and R3 are respectively current limiting resistors of CRD1 and CRD2 to protect the two constant current diodes.

R10 and R11 are collector loads of Q3 and Q4 respectively, so that Q3 and Q4 have proper working current and large dynamic range.

Based on the same design idea, the novel other specific embodiments of the present application further provide a power amplifier, which includes the voltage-current dual-feedback amplifying circuit described in the above embodiments, and can be applied to a playing device such as an earphone and a sound box. The specific implementation form of the voltage-current dual feedback amplifier circuit can be seen in the embodiments of the voltage-current dual feedback amplifier circuit, and details are not described herein.

The embodiment of the invention also provides an earphone which comprises the voltage and current double-feedback amplifying circuit. The specific implementation form of the voltage-current dual feedback amplifier circuit can be seen in the embodiments of the voltage-current dual feedback amplifier circuit, and details are not described herein.

The voltage and current dual-feedback amplifying circuit provided by the embodiment of the invention realizes the function of voltage and current dual feedback, expands the use width of the audio amplifier, and can be used for users to select different feedback modes according to the characteristics of earphones or personal listening habits, thereby obtaining the best effect and providing more choices and convenience for the users.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

What has been described above includes examples of one or more embodiments. It is, of course, not possible to describe every conceivable combination of components or methodologies for purposes of describing the aforementioned embodiments, but one of ordinary skill in the art may recognize that many further combinations and permutations of various embodiments are possible. Accordingly, the embodiments described herein are intended to embrace all such alterations, modifications and variations that fall within the scope of the appended claims. Furthermore, to the extent that the term "includes" is used in either the detailed description or the claims, such term is intended to be inclusive in a manner similar to the term "comprising" as "comprising" is interpreted when employed as a transitional word in a claim. Furthermore, any use of the term "or" in the specification of the claims is intended to mean a "non-exclusive or".

The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and all the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.