A MOS switching audio amplifier circuit

Abstract

The present application belongs to the field of audio amplification, and is a MOS switching audio amplifier circuit, comprising a switching level conversion circuit, a switching amplifier circuit and a headphone output circuit; the output end of the switching level conversion circuit is connected to the switching amplifier circuit, the output end of the switching amplifier circuit is connected to the headphone output circuit, the input end of the switching level conversion circuit is connected to an MCU, the switching amplifier circuit can generate different amplifiers to the headphone output circuit according to different high and low levels connected, and the headphone output circuit generates different audio according to different amplifiers; the switching level conversion circuit comprises an input conversion circuit, a control circuit and an output conversion circuit; the output end of the input conversion circuit is connected to the control circuit, and the output end of the control circuit is connected to the output conversion circuit; it has the advantages of small size, high space utilization, high cost efficiency, convenient operation and high signal quality.

Description

Technical Field

[0001] The present application belongs to the field of audio amplification, and in particular to a MOS switching audio amplification circuit. Background Art

[0002] There are various headphones on the market. Some headphones have low impedance and high sensitivity and do not require strong driving capabilities. High-sensitivity headphones are prone to hearing noise. When the amplification factor of the driving device is large, it is also easy to amplify the noise and hear it. Therefore, at this time, the device driving the headphones needs to switch to a smaller amplification factor.

[0003] Some headphones have high impedance and low sensitivity, which requires the driving device to have a greater driving capacity. When the amplification factor of the driving device is small, it cannot fully drive the headphones to produce high-quality sound. Headphones with low sensitivity are not easy to hear noise, so the amplification factor of the driving device can be increased. Therefore, the device driving the headphones needs to switch to a larger amplification factor.

[0004] In audio amplifier circuit design, gain control is often achieved by changing the feedback resistor. This control method can affect the frequency response, gain stability, and noise performance of the audio amplifier, and is an important consideration in designing high-quality audio amplifier circuits. The traditional feedback resistor switching method has some limitations, as follows:

[0005] 1. Relay switching scheme: Use relays to switch different feedback resistors to achieve gain adjustment. The advantage of this method is that it can provide good electrical isolation and avoid interference between circuits. However, the disadvantages include large size, high cost, limited service life, and possible noise during switching.

[0006] 2. Manual toggle switch: Open a hole in the housing and use a toggle switch to manually switch the feedback resistor. Although this method is simple, it requires the user to perform physical operations, cannot achieve remote or automatic control, and has a certain impact on the product appearance and sealing.

[0007] 3. Analog switch: Use analog switches (such as CMOS switches) to electronically switch the feedback resistor. Although smaller than relays, signal integrity and switch linearity must still be considered, which may affect the quality of the audio signal.

[0008] In summary, although there are several technologies that can realize the switching of feedback resistors, each of them is difficult to balance the simplicity of structure and flexibility. Therefore, this application aims to provide a more efficient, flexible and cost-effective switching mechanism by using MOS tubes combined with MCU's GPIO control. Summary of the invention

[0009] The purpose of the present application is to provide a MOS switching audio amplifier circuit to solve the problem that the existing feedback resistor switching method is difficult to achieve both structural simplicity and flexibility.

[0010] The technical solution of the present application is: a MOS switching audio amplification circuit, comprising a switching level conversion circuit, a switching amplification circuit and a headphone output circuit;

[0011] The output end of the switching level conversion circuit is connected to the switching amplification circuit, the output end of the switching amplification circuit is connected to the headphone output circuit, the input end of the switching level conversion circuit is connected to the MCU, and can generate different high and low levels to the switching amplification circuit according to different voltages output by the MCU, the switching amplification circuit can generate different amplification factors to the headphone output circuit according to different high and low levels connected, and the headphone output circuit generates different audio according to different amplification factors;

[0012] The switching level conversion circuit includes an input conversion circuit, a control circuit and an output conversion circuit; the output end of the input conversion circuit is connected to the control circuit, and the output end of the control circuit is connected to the output conversion circuit;

[0013] The switching amplification factor circuit includes an audio amplifier circuit, a first N-type MOS tube switching circuit, a first P-type MOS tube switching circuit, a second N-type MOS tube switching circuit and a second P-type MOS tube switching circuit; the audio amplifier circuit includes an audio amplifier chip, an L sound channel amplifier circuit and an R sound channel amplifier circuit connected to the audio amplifier chip, the L sound channel amplifier circuit is connected to the first N-type MOS tube switching circuit and the first P-type MOS tube switching circuit, and the R sound channel amplifier circuit is connected to the second N-type MOS tube switching circuit and the second P-type MOS tube switching circuit.

[0014] Preferably, the input conversion circuit includes a first resistor, a second resistor, a first MOS tube and a third resistor; one end of the first resistor is connected to the general input and output interface GAIN_RE of the MCU, and the other end is connected to the gate of the first MOS tube, one end of the second resistor is grounded, and the other end is connected to the gate of the first MOS tube; the source of the first MOS tube is grounded, and the drain is connected to one end of the third resistor, and the other end of the third resistor is connected to the control circuit; a third interface GAIN_POSITIVE for accessing the MCU power supply is provided between the first resistor and the gate of the first MOS tube.

[0015] Preferably, the control circuit includes a fourth resistor, a second MOS tube and a fifth resistor; the fourth resistor is connected to the input conversion circuit, and one end of the fourth resistor and the source of the second MOS tube are both connected to a positive voltage; the other end of the fourth resistor is connected to the gate of the second MOS tube, the drain of the second MOS tube is connected to one end of the fifth resistor, and the other end of the fifth resistor is connected to the output conversion circuit.

[0016] Preferably, the output conversion circuit includes a sixth resistor, a third MOS tube, a seventh resistor, an eighth resistor, a ninth resistor and a tenth resistor; the sixth resistor is connected to the control circuit, and one end of the sixth resistor is connected to the gate of the third MOS tube, and the other end is connected to a negative voltage, and the negative voltage is -14V; the drain of the third MOS tube is connected to a negative voltage, and the source is connected to the seventh resistor and the ninth resistor; the seventh resistor and the ninth resistor are connected in parallel with each other, and the seventh resistor is connected in series with the eighth resistor, and the ninth resistor is connected in series with the tenth resistor, and the other ends of the eighth resistor and the tenth resistor are both grounded, and a first interface GATE_NEGATIVE_L connected to the switching amplification circuit is formed between the seventh resistor and the eighth resistor; a second interface GATE_NEGATIVE_R connected to the switching amplification circuit is formed between the ninth resistor and the tenth resistor.

[0017] Preferably, the L sound channel amplifying circuit comprises an eleventh resistor, a twelfth resistor and a thirteenth resistor connected in series; one end of the eleventh resistor is grounded, and the other end is connected to pin 5 of the audio amplifier chip; one end of the twelfth resistor is connected to pin 5 of the audio amplifier chip, and the other end is connected to pin 2 of the audio amplifier chip; one end of the thirteenth resistor is connected to pin 2 of the audio amplifier chip, and the other end is the L sound channel output port AUDIO_L_OUT;

[0018] The R sound channel amplifying circuit comprises a fourteenth resistor, a fifteenth resistor and a sixteenth resistor connected in series; one end of the fourteenth resistor is grounded, and the other end is connected to the 16th pin of the audio amplifier chip; one end of the fifteenth resistor is connected to the 16th pin of the audio amplifier chip, and the other end is connected to the 19th pin of the audio amplifier chip; one end of the sixteenth resistor is connected to the 19th pin of the audio amplifier chip, and the other end is the R sound channel output port AUDIO_R_OUT;

[0019] The L sound channel output port AUDIO_L_OUT and the R sound channel output port AUDIO_R_OUT are connected to the headphone output circuit.

[0020] Preferably, the switching level conversion circuit outputs a first interface GATE_NEGATIVE_L, a second interface GATE_NEGATIVE_R and a third interface GAIN_POSITIVE;

[0021] The first N-type MOS transistor switching circuit includes a seventeenth resistor, a fourth MOS transistor and an eighteenth resistor; one end of the seventeenth resistor is connected to the third interface GAIN_POSITIVE, and the other end is connected to the gate of the fourth MOS transistor; the source of the fourth MOS transistor is grounded, and the drain is connected to the eighteenth resistor;

[0022] The first P-type MOS transistor switching circuit includes a nineteenth resistor and a fifth MOS transistor, one end of the nineteenth resistor is connected to the first interface GATE_NEGATIVE_L, and the other end is connected to the gate of the fourth MOS transistor; the drain of the fifth MOS transistor is connected to the eighteenth resistor, and the source is connected between the eleventh resistor and the twelfth resistor; the fourth MOS transistor is an N-type MOS transistor, and the fifth MOS transistor is a P-type MOS transistor;

[0023] The second N-type MOS transistor switching circuit is connected to the second interface GATE_NEGATIVE_R, and the circuit structures of the first N-type MOS transistor switching circuit and the second N-type MOS transistor switching circuit, and the first P-type MOS transistor switching circuit and the second P-type MOS transistor switching circuit are correspondingly the same.

[0024] The MOS switching audio amplifier circuit of the present application has the following advantages:

[0025] 1. Volume and space utilization: MOS tubes are used as switching elements to replace traditional relays or manual toggle switches to achieve electronic switching of feedback resistors in audio amplifier circuits, which significantly reduces the space requirements of the switching mechanism and makes the circuit design more compact, especially suitable for portable devices.

[0026] 2. Cost-effectiveness: The MOS tube is controlled through the universal input and output interface of the MCU to achieve fast and precise switching of the feedback resistance value. This is a key technical means to achieve gain adjustment. The cost of the MOS tube and related drive circuit is lower than that of traditional relays and wave switches. At the same time, it improves the reliability and durability of the overall circuit and reduces long-term maintenance costs.

[0027] 3. Operational convenience: Design a driving circuit suitable for the MOS tube to ensure that the output of the MCU can effectively drive the MOS tube, while ensuring the accuracy and stability of the switching action, improving the user experience and avoiding the impact on the product appearance.

[0028] 4. Signal quality: MOS tubes can achieve fast switching with extremely low distortion, ensuring high-quality transmission of audio signals. The performance and reliability of the entire system are guaranteed through the rational layout and matching design of the audio amplifier circuit, MOS tube and its drive circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solution provided by the present application, the following is a brief introduction to the accompanying drawings. Obviously, the accompanying drawings described below are only some embodiments of the present application.

[0030] Figure 1 This is a schematic diagram of the overall structure of this application;

[0031] Figure 2 A schematic diagram of a level conversion circuit for switching this application;

[0032] Figure 3 This is a schematic diagram of the audio amplifier circuit of this application;

[0033] Figure 4 This is a schematic diagram of a first N-type MOS transistor switching circuit and a first P-type MOS transistor switching circuit of the present application;

[0034] Figure 5 This is a schematic diagram of a second N-type MOS transistor switching circuit and a second P-type MOS transistor switching circuit of the present application;

[0035] Figure 6 This is a schematic diagram of the headphone output circuit for this application.

[0036] 1. Switching level conversion circuit; 2. Headphone output circuit; 3. Audio amplifier circuit; 4. First N-type MOS tube switching circuit; 5. First P-type MOS tube switching circuit; 6. Second N-type MOS tube switching circuit; 7. Second P-type MOS tube switching circuit; 8. First resistor; 9. Second resistor; 10. First MOS tube; 11. Third resistor; 12. Fourth resistor; 13. Second MOS tube; 14. Fifth resistor; 15. Sixth resistor; 16. Third MOS tube; 17. Seventh resistor; 18. Eighth resistor; 19. Ninth resistor; 20. Tenth resistor; 21. Audio amplifier chip; 22. Eleventh resistor; 23. Twelfth resistor; 24. Thirteenth resistor; 25. Fourteenth resistor; 26. Fifteenth resistor; 27. Sixteenth resistor; 28. Seventeenth resistor; 29. ​​Fourth MOS tube; 30. Eighteenth resistor; 31. Nineteenth resistor; 32. Fifth MOS tube. DETAILED DESCRIPTION

[0037] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] A MOS switching audio amplifier circuit, such as Figure 1, including a switching level conversion circuit 1, a switching amplification circuit and an earphone output circuit 2. The output end of the switching level conversion circuit 1 is connected to the switching amplification circuit, and the output end of the switching amplification circuit is connected to the earphone output circuit 2.

[0039] The input end of the switching level conversion circuit 1 is connected to the MCU, and can generate different high and low levels to the switching amplification circuit according to the different voltages output by the MCU. The switching amplification circuit can generate different amplification factors to the headphone output circuit 2 according to the different high and low levels connected. The headphone output circuit 2 generates different audio according to different amplification factors.

[0040] like Figure 2 The switching level conversion circuit 1 includes an input conversion circuit, a control circuit and an output conversion circuit. The output end of the input conversion circuit is connected to the control circuit, and the output end of the control circuit is connected to the output conversion circuit.

[0041] The input conversion circuit includes a first resistor 8, a second resistor 9, a first MOS transistor 10 and a third resistor 11. One end of the first resistor 8 is connected to the universal input and output interface GAIN_RE of the MCU, and the other end is connected to the gate of the first MOS transistor 10. One end of the second resistor 9 is grounded, and the other end is connected to the gate of the first MOS transistor 10. The source of the first MOS transistor 10 is grounded, and the drain is connected to one end of the third resistor 11, and the other end of the third resistor 11 is connected to the control circuit. A third interface GAIN_POSITIVE for accessing the MCU power supply is provided between the first resistor 8 and the gate of the first MOS transistor 10.

[0042] The control circuit includes a fourth resistor 12, a second MOS transistor 13 and a fifth resistor 14. The fourth resistor 12 is connected to the third resistor 11, and one end of the fourth resistor 12 and the source of the second MOS transistor 13 are both connected to a positive voltage, which is +14V; the other end of the fourth resistor 12 is connected to the gate of the second MOS transistor 13, the drain of the second MOS transistor 13 is connected to one end of the fifth resistor 14, and the other end of the fifth resistor 14 is connected to the output conversion circuit.

[0043] The output conversion circuit includes a sixth resistor 15, a third MOS tube 16, a seventh resistor 17, an eighth resistor 18, a ninth resistor 19 and a tenth resistor 20. The sixth resistor 15 is connected to the fifth resistor 14, and one end of the sixth resistor 15 is connected to the gate of the third MOS tube 16, and the other end is connected to a negative voltage, and the negative voltage is -14V. The drain of the third MOS tube 16 is connected to a negative voltage, and the source is connected to the seventh resistor 17 and the ninth resistor 19. The seventh resistor 17 and the ninth resistor 19 are connected in parallel with each other, and the seventh resistor 17 is connected in series with the eighth resistor 18, and the ninth resistor 19 is connected in series with the tenth resistor 20. The other ends of the eighth resistor 18 and the tenth resistor 20 are both grounded, and a first interface GATE_NEGATIVE_L connected to the switching amplification circuit is formed between the seventh resistor 17 and the eighth resistor 18; a second interface GATE_NEGATIVE_R connected to the switching amplification circuit is formed between the ninth resistor 19 and the tenth resistor 20. Furthermore, the first MOS transistor 10 and the third MOS transistor 16 are N-type MOS transistors, and the second MOS transistor 13 is a P-type MOS transistor.

[0044] When the MCU outputs 3.3V through the general input and output interface GAIN_RE, a high level is output to the gate of the first MOS tube 10 through the first resistor 8. At this time, the voltage of the gate of the first MOS tube 10 is greater than the voltage of the source of the first MOS tube 10, and the first MOS tube 10 is turned on; after the first MOS tube 10 is turned on, one end of the second resistor 9 is grounded and pulls down the voltage of the gate of the second MOS tube 13, so that the gate voltage of the second MOS tube 13 is less than the source voltage of the second MOS tube 13, and the second MOS tube 13 is turned on. After the second MOS tube 13 is turned on, the positive voltage +14V passes through the second MOS tube 13 to the fifth resistor 14 and the sixth resistor 15, and the sixth resistor 15 outputs a high level to the gate of the third MOS tube 16, and the gate voltage of the third MOS tube 16 is greater than the source voltage of the third MOS tube 16, and the third MOS tube 16 is turned on. The negative voltage -14V passes through the third MOS tube 16 to the seventh resistor 17 and the eighth resistor 18, and a voltage of -5.4V is generated between the seventh resistor 17 and the eighth resistor 18, so the first interface GATE_NEGATIVE_L=-5.4V; at the same time, the negative voltage -14V passes through the third MOS tube 16 to the ninth resistor 19 and the tenth resistor 20, and a voltage of -5.4V is generated between the ninth resistor 19 and the tenth resistor 20, so the second interface GATE_NEGATIVE_R=-5.4V.

[0045] When the MCU outputs 0V through the general input and output interface GAIN_RE, a low level is output to the gate of the first MOS tube 10 through the first resistor 8. At this time, the voltage of the gate of the first MOS tube 10 is less than the voltage of the source of the first MOS tube 10, and the first MOS tube 10 is not turned on; the positive voltage +14V cannot pass through the second MOS tube 13 to the fifth resistor 14 and the sixth resistor 15, and the sixth resistor 15 gives a low level to the gate of the third MOS tube 16. The gate voltage of the third MOS tube 16 is equal to the source voltage of the third MOS tube 16, and the third MOS tube 16 is not turned on. The negative voltage -14V cannot pass through the third MOS tube 16 to the seventh resistor 17 and the eighth resistor 18, and the seventh resistor 17 and the eighth resistor 18 cannot generate a voltage divider, so the first interface GATE_NEGATIVE_L=0V; at the same time, the negative voltage -14V cannot pass through the third MOS tube 16 to the ninth resistor 19 and the tenth resistor 20, and the ninth resistor 19 and the tenth resistor 20 cannot generate a voltage divider, so the second interface GATE_NEGATIVE_R=0V.

[0046] Combination Figure 3 The switching amplification circuit includes an audio amplification circuit 3, a first N-type MOS tube switching circuit 4, a first P-type MOS tube switching circuit 5, a second N-type MOS tube switching circuit 6 and a second P-type MOS tube switching circuit 7.

[0047] The audio amplifier circuit 3 includes an audio amplifier chip 21, an L sound channel amplifier circuit and an R sound channel amplifier circuit connected to the audio amplifier chip 21, the L sound channel amplifier circuit is connected to the first N-type MOS tube switching circuit 4 and the first P-type MOS tube switching circuit 5, and the R sound channel amplifier circuit is connected to the second N-type MOS tube switching circuit 6 and the second P-type MOS tube switching circuit 7. An audio input circuit is also connected to the audio amplifier chip 21, corresponding to the input interfaces AUDIO_IN_L and AUDIO_IN_R. The audio input circuit is an existing circuit and will not be described in detail.

[0048] The L sound channel amplification circuit includes an eleventh resistor 22, a twelfth resistor 23 and a thirteenth resistor 24 connected in series. One end of the eleventh resistor 22 is grounded, and the other end is connected to the 5th pin of the audio amplifier chip 21; one end of the twelfth resistor 23 is connected to the 5th pin of the audio amplifier chip 21, and the other end is connected to the 2nd pin of the audio amplifier chip 21; one end of the thirteenth resistor 24 is connected to the 2nd pin of the audio amplifier chip 21, and the other end is the L sound channel output port AUDIO_L_OUT.

[0049] The R sound channel amplification circuit includes a fourteenth resistor 25, a fifteenth resistor 26, and a sixteenth resistor 27 connected in series. One end of the fourteenth resistor 25 is grounded, and the other end is connected to the 16th pin of the audio amplifier chip 21; one end of the fifteenth resistor 26 is connected to the 16th pin of the audio amplifier chip 21, and the other end is connected to the 19th pin of the audio amplifier chip 21; one end of the sixteenth resistor 27 is connected to the 19th pin of the audio amplifier chip 21, and the other end is the R sound channel output port AUDIO_R_OUT.

[0050] The L sound channel output port AUDIO_L_OUT and the R sound channel output port AUDIO_R_OUT are connected to the headphone output circuit 2 for realizing audio output. Figure 6 .

[0051] Combination Figure 4 The first N-type MOS transistor switching circuit 4 includes a seventeenth resistor 28, a fourth MOS transistor 29 and an eighteenth resistor 30. One end of the seventeenth resistor 28 is connected to the third interface GAIN_POSITIVE, and the other end is connected to the gate of the fourth MOS transistor 29. The source of the fourth MOS transistor 29 is grounded, and the drain is connected to the eighteenth resistor 30.

[0052] The first P-type MOS transistor switching circuit 5 includes a nineteenth resistor 31 and a fifth MOS transistor 32. One end of the nineteenth resistor 31 is connected to the first interface GATE_NEGATIVE_L, and the other end is connected to the gate of the fourth MOS transistor 29. The drain of the fifth MOS transistor 32 is connected to the eighteenth resistor 30, and the source is connected between the eleventh resistor 22 and the twelfth resistor 23. The fourth MOS transistor 29 is an N-type MOS transistor, and the fifth MOS transistor 32 is a P-type MOS transistor.

[0053] Combination Figure 5 , the second N-type MOS transistor switching circuit 6 is connected to the second interface GATE_NEGATIVE_R, the first N-type MOS transistor switching circuit 4 and the second N-type MOS transistor switching circuit 6, the first P-type MOS transistor switching circuit 5 and the second P-type MOS transistor switching circuit 7 have the same circuit structure and the same working principle, and the first N-type MOS transistor switching circuit 4 and the first P-type MOS transistor switching circuit 5 are used as examples for description below:

[0054] When the magnification is not required, the MCU outputs 0V.

[0055] The third interface GAIN_POSITIVE=0V;

[0056] First interface GATE_NEGATIVE_L=0;

[0057] The second interface GATE_NEGATIVE_R=0V;

[0058] The gate of the fourth MOS transistor 29 is at a low level, and its gate voltage is less than the source voltage, so the fourth MOS transistor 29 is not conducting; the source of the fifth MOS transistor 32 is 0V, which is the same as the voltage of its gate, and both are 0V, so the fifth MOS transistor 32 is not conducting, and at this time, the amplification factor of the L channel is the ratio of the twelfth resistor 23 to the eleventh resistor 22. The same is true for the R channel, and its amplification factor is the ratio of the fifteenth resistor 26 to the fourteenth resistor 25.

[0059] When the magnification is required, the MCU outputs 3.3V. At this time:

[0060] The third interface GAIN_POSITIVE=3.3V;

[0061] First interface GATE_NEGATIVE_L=-5.4V;

[0062] The second interface GATE_NEGATIVE_R=-5.4V;

[0063] The gate of the fourth MOS transistor 29 is at a high level, and its gate voltage is greater than the source voltage, so the fourth MOS transistor 29 is turned on; the source of the fifth MOS transistor 32 is 0V, the gate is -5.4V, and the gate voltage is less than the source voltage, so the fifth MOS transistor 32 is turned on. At this time, the amplification factor of the L channel is determined by the ratio of the twelfth resistor 23 and the ratio resistor eleventh resistor 22 and eighteenth resistor 30. The same is true for the R channel, and no further details are given.

[0064] In summary, this application has the following advantages:

[0065] 1. Volume and space utilization: MOS tubes are used as switching elements to replace traditional relays or manual toggle switches to achieve electronic switching of feedback resistors in audio amplifier circuits, which significantly reduces the space requirements of the switching mechanism and makes the circuit design more compact, especially suitable for portable devices.

[0066] 2. Cost-effectiveness: The MOS tube is controlled through the universal input and output interface of the MCU to achieve fast and precise switching of the feedback resistance value. This is a key technical means to achieve gain adjustment. The cost of the MOS tube and related drive circuit is lower than that of traditional relays and wave switches. At the same time, it improves the reliability and durability of the overall circuit and reduces long-term maintenance costs.

[0067] 3. Operational convenience: Design a driving circuit suitable for the MOS tube to ensure that the output of the MCU can effectively drive the MOS tube, while ensuring the accuracy and stability of the switching action, improving the user experience and avoiding the impact on the product appearance.

[0068] 4. Signal quality: MOS tubes can achieve fast switching with extremely low distortion, ensuring high-quality transmission of audio signals. The performance and reliability of the entire system are guaranteed through the rational layout and matching design of the audio amplifier circuit, MOS tube and its drive circuit.

[0069] Finally, it should be noted that: the drawings of the embodiments disclosed in the present invention only involve structures related to the embodiments disclosed in the present invention, and other structures can refer to the general design. In the absence of conflict, the same embodiment and different embodiments of the present invention can be combined with each other;

[0070] Finally: The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A MOS switching audio amplifier circuit, characterized in that: It includes a switching level conversion circuit (1), a switching amplification circuit and a headphone output circuit (2); The output end of the switching level conversion circuit (1) is connected to the switching amplification circuit, the output end of the switching amplification circuit is connected to the headphone output circuit (2), the input end of the switching level conversion circuit (1) is connected to the MCU, and can generate different high and low levels to the switching amplification circuit according to different voltages output by the MCU, the switching amplification circuit can generate different amplification factors to the headphone output circuit (2) according to different high and low levels connected, and the headphone output circuit (2) generates different audio according to different amplification factors; The switching level conversion circuit (1) comprises an input conversion circuit, a control circuit and an output conversion circuit; the output end of the input conversion circuit is connected to the control circuit, and the output end of the control circuit is connected to the output conversion circuit; The switching amplification factor circuit comprises an audio amplifier circuit (3), a first N-type MOS tube switching circuit (4), a first P-type MOS tube switching circuit (5), a second N-type MOS tube switching circuit (6) and a second P-type MOS tube switching circuit (7); the audio amplifier circuit (3) comprises an audio amplifier chip (21), an L sound channel amplifier circuit and an R sound channel amplifier circuit connected to the audio amplifier chip (21); the L sound channel amplifier circuit is connected to the first N-type MOS tube switching circuit (4) and the first P-type MOS tube switching circuit (5); the R sound channel amplifier circuit is connected to the second N-type MOS tube switching circuit (6) and the second P-type MOS tube switching circuit (7); The L sound channel amplification circuit comprises an eleventh resistor (22), a twelfth resistor (23) and a thirteenth resistor (24) which are connected in series; one end of the eleventh resistor (22) is grounded, and the other end is connected to pin 5 of the audio amplifier chip (21); one end of the twelfth resistor (23) is connected to pin 5 of the audio amplifier chip (21), and the other end is connected to pin 2 of the audio amplifier chip (21); one end of the thirteenth resistor (24) is connected to pin 2 of the audio amplifier chip (21), and the other end is the L sound channel output port AUDIO_L_OUT; The R sound channel amplification circuit comprises a fourteenth resistor (25), a fifteenth resistor (26) and a sixteenth resistor (27) which are connected in series; one end of the fourteenth resistor (25) is grounded, and the other end is connected to the 16th pin of the audio amplifier chip (21); one end of the fifteenth resistor (26) is connected to the 16th pin of the audio amplifier chip (21), and the other end is connected to the 19th pin of the audio amplifier chip (21); one end of the sixteenth resistor (27) is connected to the 19th pin of the audio amplifier chip (21), and the other end is the R sound channel output port AUDIO_R_OUT; The L sound channel output port AUDIO_L_OUT and the R sound channel output port AUDIO_R_OUT are connected to the headphone output circuit (2); The switching level conversion circuit (1) outputs a first interface GATE_NEGATIVE_L, a second interface GATE_NEGATIVE_R and a third interface GAIN_POSITIVE; The first N-type MOS transistor switching circuit (4) comprises a seventeenth resistor (28), a fourth MOS transistor (29) and an eighteenth resistor (30); one end of the seventeenth resistor (28) is connected to the third interface GAIN_POSITIVE, and the other end is connected to the gate of the fourth MOS transistor (29); the source of the fourth MOS transistor (29) is grounded, and the drain is connected to the eighteenth resistor (30); The first P-type MOS transistor switching circuit (5) comprises a nineteenth resistor (31) and a fifth MOS transistor (32); one end of the nineteenth resistor (31) is connected to the first interface GATE_NEGATIVE_L, and the other end is connected to the gate of the fourth MOS transistor (29); the source of the fifth MOS transistor (32) is connected to the eighteenth resistor (30), and the drain is connected between the fourteenth resistor (25) and the fifteenth resistor (26); the fourth MOS transistor (29) is an N-type MOS transistor, and the fifth MOS transistor (32) is a P-type MOS transistor; The second N-type MOS transistor switching circuit (6) is connected to the second interface GATE_NEGATIVE_R, and the circuit structures of the first N-type MOS transistor switching circuit (4) and the second N-type MOS transistor switching circuit (6), and the first P-type MOS transistor switching circuit (5) and the second P-type MOS transistor switching circuit (7) are correspondingly the same.

2. The MOS switching audio amplifier circuit according to claim 1, characterized in that: The input conversion circuit comprises a first resistor (8), a second resistor (9), a first MOS transistor (10) and a third resistor (11); one end of the first resistor (8) is connected to the universal input / output interface GAIN_RE of the MCU, and the other end is connected to the gate of the first MOS transistor (10); one end of the second resistor (9) is grounded, and the other end is connected to the gate of the first MOS transistor (10); the source of the first MOS transistor (10) is grounded, and the drain is connected to one end of the third resistor (11), and the other end of the third resistor (11) is connected to the control circuit; a third interface GAIN_POSITIVE for connecting to the MCU power supply is provided between the first resistor (8) and the gate of the first MOS transistor (10).

3. The MOS switching audio amplifier circuit according to claim 1, characterized in that: The control circuit comprises a fourth resistor (12), a second MOS transistor (13) and a fifth resistor (14); the fourth resistor (12) is connected to the input conversion circuit, and one end of the fourth resistor (12) and the source of the second MOS transistor (13) are both connected to a positive voltage; the other end of the fourth resistor (12) is connected to the gate of the second MOS transistor (13), the drain of the second MOS transistor (13) is connected to one end of the fifth resistor (14), and the other end of the fifth resistor (14) is connected to the output conversion circuit.

4. The MOS switching audio amplifier circuit according to claim 1, characterized in that: The output conversion circuit comprises a sixth resistor (15), a third MOS tube (16), a seventh resistor (17), an eighth resistor (18), a ninth resistor (19) and a tenth resistor (20); the sixth resistor (15) is connected to the control circuit, and one end of the sixth resistor (15) is connected to the gate of the third MOS tube (16), and the other end is connected to a negative voltage, the negative voltage is -14V; the source of the third MOS tube (16) is connected to the negative voltage, and the drain is connected to the seventh resistor (17) and the ninth resistor (19); the seventh resistor (17) and the eighth resistor (18) are ... The nine resistors (19) are connected in parallel with each other, and the seventh resistor (17) is connected in series with the eighth resistor (18), and the ninth resistor (19) is connected in series with the tenth resistor (20). The other ends of the eighth resistor (18) and the tenth resistor (20) are both grounded. A first interface GATE_NEGATIVE_L connected to the switching amplification circuit is formed between the seventh resistor (17) and the eighth resistor (18); and a second interface GATE_NEGATIVE_R connected to the switching amplification circuit is formed between the ninth resistor (19) and the tenth resistor (20).

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