CN107948866B - Feedback interference low-distortion audio playing system - Google Patents
Feedback interference low-distortion audio playing system Download PDFInfo
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- CN107948866B CN107948866B CN201810007529.4A CN201810007529A CN107948866B CN 107948866 B CN107948866 B CN 107948866B CN 201810007529 A CN201810007529 A CN 201810007529A CN 107948866 B CN107948866 B CN 107948866B
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R3/00—Circuits for transducers, loudspeakers or microphones
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R2430/00—Signal processing covered by H04R, not provided for in its groups
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Abstract
The invention discloses a feedback interference low-distortion audio playing system, which is characterized in that: the circuit comprises an operational amplifier U2, an audio receiving module, a band-pass filter circuit connected with the audio receiving module, a resistor R13 connected between 1 pin and 3 pin of the operational amplifier U2 in series, a polar capacitor C6, a potentiometer R15, a polar capacitor C5 connected with 11 pin of the operational amplifier U2 after the positive electrode is connected with the 1 pin of the operational amplifier U2 and the negative electrode sequentially passes through the polar capacitor R14 and the resistor R15, and the like. The invention can isolate the interference noise outside the set range, effectively remove the interference noise and improve the communication effect. The invention can reduce the distortion degree of the amplified audio signal, thereby improving the communication effect. The invention can isolate the interference signals fed back by the back electrode circuit and the loudspeaker, thereby improving the stability of the audio signal.
Description
Technical Field
The invention relates to an audio system, in particular to a feedback interference low-distortion audio playing system.
Background
With the continuous development of electronic technology, electronic communication devices have been popularized, and great convenience is brought. However, the audio output system used in the existing electronic communication device has the defects that the output sound is more and the conversation is not clear enough, so that the conversation quality is greatly affected.
Disclosure of Invention
The invention aims to overcome the defects of more sound murmurs and unclear conversation output by an audio output system and provides a feedback interference low-distortion audio playing system.
The aim of the invention is achieved by the following technical scheme: the feedback interference low-distortion audio playing system comprises an operational amplifier U2, an audio receiving module, a band-pass filter circuit connected with the audio receiving module, a resistor R13 connected in series between 1 pin and 3 pin of the operational amplifier U2, a polar capacitor C5, a resistor R17, a resistor R11 and a loudspeaker BT, wherein the positive electrode of the polar capacitor C5 is connected with the 1 pin of the operational amplifier U2, the negative electrode of the polar capacitor C5 is connected with the 11 pin of the operational amplifier U2 after passing through a polar capacitor C6, a potentiometer R15 and a resistor R14 in sequence, one end of the polar capacitor C5 is connected with the 1 pin of the operational amplifier U2, the other end of the polar capacitor R17 is connected with the control end of the potentiometer R15 after passing through a resistor R16, one end of the resistor R11 is connected with the 2 pin of the operational amplifier U2, the other end of the resistor R11 is connected with the 2 pin of the operational amplifier U2, and the loudspeaker BT is connected with the low-distortion audio amplifying circuit; and the 2 pin of the operational amplifier U2 is connected with a connection point of the resistor R17 and the resistor R16, and the 3 pin is connected with a band-pass filter circuit.
Further, the low-distortion audio amplifying circuit comprises an amplifying chip U1, a distortion adjusting circuit connected with the amplifying chip U1, a polarity capacitor C7 with the positive electrode connected with the 3 pin of the amplifying chip U1 and the negative electrode grounded, and a resistor R18 with one end connected with the positive electrode of the polarity capacitor C7 and the other end connected with a power supply; the 2 pin of the amplifying chip U1 is connected with the 1 pin of the operational amplifier U2, and the distortion regulating circuit is connected with the loudspeaker BT.
The distortion regulating circuit comprises a triode Q1, a triode Q2, a polar capacitor C9, a polar capacitor C10, a diode D3, a resistor R22, a resistor R19, a capacitor C8, a resistor R21, a polar capacitor C10, and a voltage stabilizing diode D2, wherein the positive electrode of the polar capacitor C9 is connected with the emitter of the triode Q2, the negative electrode of the polar capacitor C9 is connected with the loudspeaker BT, the P electrode of the polar capacitor C9 is connected with the negative electrode of the polar capacitor C9, the N electrode of the diode D3 is connected with the collector of the triode Q2 after passing through the resistor R22, one end of the diode D is connected with the 2 pin of the amplifying chip U1, the other end of the diode D19 is connected with the emitter of the triode Q2 after passing through the potentiometer R20, the capacitor C8 is connected between the base and the emitter of the triode Q1 in series, the resistor R21 is connected between the collector and the emitter of the triode Q1 in series, the positive electrode of the polar capacitor C10 is connected with the collector of the triode Q1, the negative electrode of the polar capacitor is grounded; the collector of the triode Q1 is connected with a power supply, the emitter is connected with the emitter of the triode Q2, and the base is connected with the base of the triode Q2; the 7 pin of the amplifying chip U1 is connected with the collector electrode of the triode Q1, the 6 pin is connected with the base electrode of the triode Q1, and the 4 pin is grounded; the collector of the triode Q2 is grounded, and the emitter of the triode Q is connected with the control end of the potentiometer R20.
The band-pass filter circuit comprises a second-order high-pass filter circuit connected with the audio receiving module, and a second-order low-pass filter circuit connected between the second-order high-pass filter circuit and the 3 pin of the operational amplifier U2 in series.
The second-order high-pass filter circuit comprises an operational amplifier A1, a capacitor C1, a diode D1, a resistor R2, a resistor R4 and a resistor R1, wherein one end of the capacitor C1 is connected with the audio receiving module, the other end of the capacitor C1 is connected with the positive electrode of the operational amplifier A1 after passing through the capacitor C2, the P electrode of the capacitor D1 is grounded after passing through the resistor R3, the N electrode of the diode D1 is connected with a connecting point of the capacitor C1 and the capacitor C2, the resistor R2 is connected between the N electrode of the diode D1 and the output end of the operational amplifier A1 in series, the resistor R4 is connected between the output end of the operational amplifier A1 and the P electrode of the diode D1 in series, and the resistor R1 is connected with the positive electrode of the operational amplifier A1 at one end and the other end of the resistor R1 is grounded; the output end of the operational amplifier A1 is connected with a second-order low-pass filter circuit, and the negative electrode of the operational amplifier A1 is connected with the P electrode of the diode D1.
The second-order low-pass filter circuit comprises an operational amplifier A2, a resistor R5, a capacitor C4, a resistor R8, a capacitor C3, a resistor R6 and a resistor R9, wherein one end of the resistor R5 is connected with the output end of the operational amplifier A1, the other end of the resistor R5 is connected with the positive electrode of the operational amplifier A2 after passing through the resistor R7, one end of the resistor R4 is connected with the connection point of the resistor R5 and the resistor R7, the other end of the resistor R8 is connected with the output end of the operational amplifier A2 in parallel, one end of the resistor R8 is connected with the positive electrode of the operational amplifier A2, the other end of the resistor C3 is grounded, and the other end of the resistor R9 is connected with the output end of the operational amplifier A2 after passing through the resistor R10; the negative electrode of the operational amplifier A2 is connected with a connection point of the resistor R9 and the resistor R10, and the output end of the operational amplifier A2 is connected with the 3 pin of the operational amplifier U2.
The center frequency of the second-order high-pass filter circuit isThe center frequency of the second-order low-pass filter circuit is +.>
Gain A of the second-order high-pass filter circuit F1 Gain A equal to second order low pass filter circuit F2 The method comprises the following steps:gain A of the band-pass filter circuit F ＝A F1 A F2 。
The cut-off frequency of the band-pass filter circuit is 300-3000 Hz.
Compared with the prior art, the invention has the following advantages:
(1) The invention can isolate the interference noise outside the set range, effectively remove the interference noise and improve the communication effect.
(2) The invention can reduce the distortion degree of the amplified audio signal, thereby improving the communication effect.
(3) The invention can isolate the interference signals fed back by the back electrode circuit and the loudspeaker, thereby improving the stability of the audio signal.
Drawings
Fig. 1 is a schematic diagram of the overall structure of the present invention.
Detailed Description
The present invention will be described in further detail with reference to examples, but embodiments of the present invention are not limited thereto.
Examples
As shown in FIG. 1, the feedback interference low-distortion audio playing system comprises an operational amplifier U2, an audio receiving module, a band-pass filter circuit connected with the audio receiving module, a resistor R13 connected in series between 1 pin and 3 pin of the operational amplifier U2, a polar capacitor C5 with the positive pole connected with 11 pin of the operational amplifier U2 after passing through a polar capacitor C6, a potentiometer R15 and a resistor R14 in sequence, a resistor R17 with one end connected with 1 pin of the operational amplifier U2 and the other end connected with the control end of the potentiometer R15 after passing through a resistor R16, a resistor R11 with one end connected with 3 pin of the operational amplifier U2 and the other end connected with 2 pin of the operational amplifier U2 after passing through a resistor R12, a low-distortion audio amplifying circuit connected with 1 pin of the operational amplifier U2, and a loudspeaker BT connected with the low-distortion audio amplifying circuit. And the 2 pin of the operational amplifier U2 is connected with a connection point of the resistor R17 and the resistor R16, and the 3 pin is connected with a band-pass filter circuit.
Specifically, the audio receiving module is configured to receive an audio signal, which may be implemented using an existing antenna. The filtering frequency of the band-pass filter circuit is 300-3000 Hz, and the band-pass filter circuit can effectively filter interference noise and keep a speaking audio signal, so that the sound output by the band-pass filter circuit is clearer.
In order to filter the interference signal, as shown in fig. 1, the band-pass filter circuit includes a second-order high-pass filter circuit connected with the audio receiving module, and a second-order low-pass filter circuit connected in series between the second-order high-pass filter circuit and the 3 pin of the op-amp U2.
Specifically, the second-order high-pass filter circuit includes an operational amplifier A1, a capacitor C2, a resistor R1, a resistor R2, a resistor R3, a resistor R4, and a diode D1.
When in connection, one end of the capacitor C1 is connected with the audio receiving module, and the other end of the capacitor C1 is connected with the positive electrode of the operational amplifier A1 after passing through the capacitor C2. The P pole of the diode D1 is grounded through a resistor R3, and the N pole is connected with a connecting point of the capacitor C1 and the capacitor C2. The resistor R2 is connected in series between the N pole of the diode D1 and the output terminal of the operational amplifier A1. The resistor R4 is connected in series between the output of the operational amplifier A1 and the P pole of the diode D1. One end of the resistor R1 is connected with the positive electrode of the operational amplifier A1, and the other end is grounded. The output end of the operational amplifier A1 is connected with a second-order low-pass filter circuit, and the negative electrode of the operational amplifier A1 is connected with the P electrode of the diode D1.
The audio signal output by the audio receiving module is filtered by a capacitor C1 and a capacitor C2 and then is input to an operational amplifier A1, and the operational amplifier A1, the capacitor C2, a resistor R4 and a resistor R3 jointly form a high-pass filter; the operational amplifier A1 is a negative feedback, which can stabilize the gain of the circuit. The center frequency of the second-order high-pass filter circuit isIn this embodiment, the capacitance values of the capacitor C1 and the capacitor C2 are both 0.068 μf, and the resistance values of the resistor R1 and the resistor R2 are both 8.2kΩ; as can be seen from the above formula, the center frequency f of the second-order high-pass filter circuit in this embodiment 1 =286 Hz. The diode D1 has a model 14001, the resistor R4 has a resistance of 27kΩ, the resistor R3 has a resistance of 47kΩ, and the operational amplifier A1 has a model OP07. The audio signal output from the operational amplifier A1 is input to a second-order low-pass filter circuit.
As shown in fig. 1, the second-order low-pass filter circuit includes an operational amplifier A2, a resistor R5, a resistor R7, a resistor R6, a resistor R8, a resistor R9, a resistor R10, a capacitor C3, and a capacitor C4. In the specific connection, one end of the resistor R5 is connected to the output end of the operational amplifier A1, and the other end is connected to the positive electrode of the operational amplifier A2 via the resistor R7. One end of the capacitor C4 is connected to the connection point of the resistor R5 and the resistor R7, and the other end is connected to the output end of the operational amplifier A2. Resistor R8 is connected in parallel with capacitor C4. One end of the capacitor C3 is connected with the positive electrode of the operational amplifier A2, and the other end is grounded. Resistor R6 is connected in parallel with capacitor C3. One end of the resistor R9 is connected with the output end of the operational amplifier A2, and the other end is grounded after passing through the resistor R10. The negative electrode of the operational amplifier A2 is connected with a connection point of the resistor R9 and the resistor R10, and the output end of the operational amplifier A2 is connected with the 3 pin of the operational amplifier U2.
The audio signal output by the operational amplifier A1 is input to the operational amplifier A2 through the resistor R5 and the resistor R7, and meanwhile, the capacitor C3 and the capacitor C4 can filter the audio signal; the operational amplifier A2, the resistor R5, the resistor R7, the capacitor C3, the resistor R6, the capacitor C4, and the resistor R8 together form a low-pass filter. The operational amplifier A2 is also negative feedback, which can stabilize the gain of the circuit. The center frequency of the second-order low-pass filter circuit isIn this embodiment, the resistance values of the resistor R5 and the resistor R7 are 8.2kΩ, and the capacitance values of the capacitor C3 and the capacitor C4 are 0.0068 μf; as can be seen from the above formula, the center frequency f of the second-order low-pass filter circuit in this embodiment 2 =2856 Hz. The resistance of the resistor R6 is 10kΩ, the resistance of the resistor R8 is 1kΩ, the resistance of the resistor R9 is 27kΩ, the resistance of the resistor R10 is 47kΩ, and the model of the operational amplifier A2 is OP07.
From the above, the cut-off frequency of the band-pass filter circuit of this embodiment is 286Hz to 2856Hz, so that the interference signals except the speaking voice frequency signal are effectively isolated, and the conversation quality is improved.
In addition, the gain A of the second-order high-pass filter circuit F1 Gain A equal to second order low pass filter circuit F2 The method comprises the following steps:gain A of the band-pass filter circuit F ＝A F1 A F2 。
In addition, the operational amplifier U2, the polar capacitor C5, the polar capacitor C6, the resistor R17, the resistor R16, the potentiometer R15 and the resistor R14 together form an isolation buffer; the isolation buffer can isolate feedback interference signals of the rear-stage low-distortion audio amplifying circuit and the loudspeaker BT, so that the stability of the system is improved. In this embodiment, the model number of the operational amplifier U2 is LM324, the capacitance value of the polar capacitor C5 is 1 μf, the capacitance value of the polar capacitor C6 is 4.7 μf, the resistance value of the resistor R17 is 10kΩ, the resistance value of the resistor R16 is 100deg.kΩ, the resistance value of the potentiometer R15 is 10kΩ, the resistance value of the resistor R14 is 4.7kΩ, the resistance value of the resistor R12 is 100deg.kΩ, the resistance value of the resistor R11 is 4.7kΩ, and the resistance value of the resistor R13 is 22kΩ. The audio signal is output from the 1 pin of the operational amplifier U2 to the low distortion audio amplifying circuit.
The low-distortion audio amplifying circuit comprises an amplifying chip U1, a distortion adjusting circuit connected with the amplifying chip U1, a polarity capacitor C7 with the positive electrode connected with the 3 pin of the amplifying chip U1 and the negative electrode grounded, and a resistor R18 with one end connected with the positive electrode of the polarity capacitor C7 and the other end connected with a power supply. The 2 pin of the amplifying chip U1 is connected with the output end of the operational amplifier A2, and the distortion adjusting circuit is connected with the loudspeaker BT.
The polar capacitor C7 can carry out filtering treatment on the input voltage, so that the operation of the amplifying chip U1 is more stable; the resistor R18 has a voltage dividing function, the resistance value of the resistor R18 is 10KΩ, the capacitance value of the polar capacitor C7 is 0.1 μF,
the distortion adjusting circuit includes a transistor Q1, a transistor Q2, a resistor R19, a potentiometer R20, a zener diode D2, a capacitor C8, a resistor R22, a polarity capacitor C9, a polarity capacitor C10, a resistor R21, and a diode D3.
The positive electrode of the polar capacitor C9 is connected to the emitter of the transistor Q2, and the negative electrode is connected to the speaker BT. The P pole of the diode D3 is connected with the negative pole of the polar capacitor C9, and the N pole is connected with the collector of the triode Q2 after passing through the resistor R22. One end of the resistor R19 is connected with the 2 pin of the amplifying chip U1, and the other end of the resistor R is connected with the emitter of the triode Q2 after passing through the potentiometer R20. The capacitor C8 is connected in series between the base and emitter of the transistor Q1. Resistor R21 is connected in series between the collector and emitter of transistor Q1. The positive pole of the polar capacitor C10 is connected with the collector electrode of the triode Q1, and the negative pole is grounded. The N pole of the zener diode D2 is connected with the collector of the triode Q1, and the P pole is grounded.
The collector of the triode Q1 is connected with a power supply, the emitter is connected with the emitter of the triode Q2, and the base is connected with the base of the triode Q2. And the 7 pin of the amplifying chip U1 is connected with the collector electrode of the triode Q1, the 6 pin is connected with the base electrode of the triode Q1, the 4 pin is grounded, and the 2 pin is connected with the 1 pin of the operational amplifier U2. The collector of the triode Q2 is grounded, and the emitter of the triode Q is connected with the control end of the potentiometer R20.
The triode Q1 and the triode Q2 form a complementary structure, and the potentiometer R20 and the resistor R19 are combined to form a feedback loop of the amplifying chip U1, so that the structure can reduce distortion of signals in the transmission process. The capacitor C8 may act as a filter with a capacitance of 0.1 muf. Adjusting potentiometer R20 can adjust the gain range of the distortion adjustment circuit. The polar capacitor C10 can filter the input voltage, and the zener diode D2 can stabilize the voltage, so as to improve the stability of the amplifying chip U1. The resistance of the resistor R19 is 1KΩ, the resistance of the potentiometer R20 is 20KΩ, the resistance of the resistor R22 is 10KΩ, the resistance of the resistor R21 is 100KΩ, the capacitance of the capacitor C8 is 0.1 μF, the capacitance of the polar capacitor C9 is 4.7 μF, the capacitance of the polar capacitor C10 is 470 μF, the model of the diode D3 is 1N4003, the model of the zener diode D2 is 1N4742, and the model of the amplifying chip U1 is LM74.
The audio signal output by the second-order high-pass filter circuit is input into the amplifying chip U1 for amplifying, is output from the 6 pin of the amplifying chip U1, and drives the triode Q1 and the triode Q2 which are complementarily arranged and then drives the loudspeaker BT to sound.
As described above, the present invention can be well implemented.
Claims (9)
1. A feedback interference low distortion audio playback system, characterized by: the low-distortion audio amplifier comprises an operational amplifier U2, an audio receiving module, a band-pass filter circuit connected with the audio receiving module, a resistor R13 connected in series between 1 pin and 3 pin of the operational amplifier U2, a polar capacitor C5, a resistor R17, a resistor R11 and a loudspeaker BT, wherein the positive electrode of the resistor R13 is connected with the 1 pin of the operational amplifier U2, the negative electrode of the polar capacitor C5 is connected with the 11 pin of the operational amplifier U2 after passing through a polar capacitor C6, a potentiometer R15 and a resistor R14 in sequence, one end of the polar capacitor C5 is connected with the 1 pin of the operational amplifier U2, the other end of the resistor R17 is connected with the control end of the potentiometer R15 after passing through the resistor R16, one end of the resistor R11 is connected with the 3 pin of the operational amplifier U2, the other end of the resistor R12 is connected with the 2 pin of the operational amplifier U2, and the loudspeaker BT is connected with the low-distortion audio amplifier circuit; the 2 pin of the operational amplifier U2 is connected with a connection point of the resistor R17 and the resistor R16, the 3 pin of the operational amplifier U2 is connected with a band-pass filter circuit, and the model of the operational amplifier U2 is LM324.
2. The feedback interference low distortion audio playback system of claim 1, wherein: the low-distortion audio amplifying circuit comprises an amplifying chip U1, a distortion regulating circuit connected with the amplifying chip U1, a polarity capacitor C7 with the positive electrode connected with the 3 pin of the amplifying chip U1 and the negative electrode grounded, and a resistor R18 with one end connected with the positive electrode of the polarity capacitor C7 and the other end connected with a power supply; the 2 pin of the amplifying chip U1 is connected with the 1 pin of the operational amplifier U2, and the distortion regulating circuit is connected with the loudspeaker BT.
3. The feedback interference low distortion audio playback system of claim 2, wherein: the distortion regulating circuit comprises a triode Q1, a triode Q2, a polar capacitor C9, a polar capacitor C10, a diode D3, a resistor R22, a resistor R19, a capacitor C8, a resistor R21, a polar capacitor C10, and a voltage stabilizing diode D2, wherein the positive electrode of the polar capacitor C9 is connected with the emitter of the triode Q2, the negative electrode of the polar capacitor C9 is connected with the loudspeaker BT, the P electrode of the polar capacitor C9 is connected with the negative electrode of the polar capacitor C9, the N electrode of the diode D3 is connected with the collector of the triode Q2 after passing through the resistor R22, one end of the diode D is connected with the 2 pin of the amplifying chip U1, the other end of the diode D19 is connected with the emitter of the triode Q2 after passing through the potentiometer R20, the capacitor C8 is connected between the base and the emitter of the triode Q1 in series, the resistor R21 is connected between the collector and the emitter of the triode Q1 in series, the positive electrode of the polar capacitor C10 is connected with the collector of the triode Q1, the negative electrode of the polar capacitor is grounded; the collector of the triode Q1 is connected with a power supply, the emitter is connected with the emitter of the triode Q2, and the base is connected with the base of the triode Q2; the 7 pin of the amplifying chip U1 is connected with the collector electrode of the triode Q1, the 6 pin is connected with the base electrode of the triode Q1, and the 4 pin is grounded; the collector of the triode Q2 is grounded, and the emitter of the triode Q is connected with the control end of the potentiometer R20.
4. A feedback interference low distortion audio playback system as claimed in claim 3, characterized in that: the band-pass filter circuit comprises a second-order high-pass filter circuit connected with the audio receiving module, and a second-order low-pass filter circuit connected between the second-order high-pass filter circuit and the 3 pin of the operational amplifier U2 in series.
5. The feedback interference low distortion audio playback system of claim 4, wherein: the second-order high-pass filter circuit comprises an operational amplifier A1, a capacitor C1, a diode D1, a resistor R2, a resistor R4 and a resistor R1, wherein one end of the capacitor C1 is connected with the audio receiving module, the other end of the capacitor C1 is connected with the positive electrode of the operational amplifier A1 after passing through the capacitor C2, the P electrode of the capacitor D1 is grounded after passing through the resistor R3, the N electrode of the diode D1 is connected with a connecting point of the capacitor C1 and the capacitor C2, the resistor R2 is connected between the N electrode of the diode D1 and the output end of the operational amplifier A1 in series, the resistor R4 is connected between the output end of the operational amplifier A1 and the P electrode of the diode D1 in series, and the resistor R1 is connected with the positive electrode of the operational amplifier A1 at one end and the other end of the resistor R1 is grounded; the output end of the operational amplifier A1 is connected with a second-order low-pass filter circuit, and the negative electrode of the operational amplifier A1 is connected with the P electrode of the diode D1.
6. The feedback interference low distortion audio playback system of claim 5, wherein: the second-order low-pass filter circuit comprises an operational amplifier A2, a resistor R5, a capacitor C4, a resistor R8, a capacitor C3, a resistor R6 and a resistor R9, wherein one end of the resistor R5 is connected with the output end of the operational amplifier A1, the other end of the resistor R5 is connected with the positive electrode of the operational amplifier A2 after passing through the resistor R7, one end of the resistor R4 is connected with the connection point of the resistor R5 and the resistor R7, the other end of the resistor R8 is connected with the output end of the operational amplifier A2 in parallel, one end of the resistor R8 is connected with the positive electrode of the operational amplifier A2, the other end of the resistor C3 is grounded, and the other end of the resistor R9 is connected with the output end of the operational amplifier A2 after passing through the resistor R10; the negative electrode of the operational amplifier A2 is connected with a connection point of the resistor R9 and the resistor R10, and the output end of the operational amplifier A2 is connected with the 3 pin of the operational amplifier U2.
7. The feedback interference low distortion audio playback system of claim 6, wherein: the center frequency of the second-order high-pass filter circuit isThe center frequency of the second-order low-pass filter circuit is
8. The feedback interference low distortion audio playback system of claim 7, wherein: gain A of the second-order high-pass filter circuit F1 Gain A equal to second order low pass filter circuit F2 The method comprises the following steps:gain A of the band-pass filter circuit F ＝A F1 A F2 。
9. The feedback interference low distortion audio playback system of claim 8, wherein: the cut-off frequency of the band-pass filter circuit is 300-3000 Hz.
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| CN201810007529.4A CN107948866B (en) | 2018-01-04 | 2018-01-04 | Feedback interference low-distortion audio playing system |
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| CN204046585U (en) * | 2014-09-05 | 2014-12-24 | 国家电网公司 | A kind of AM receiving circuitry |
| CN105848060A (en) * | 2016-05-28 | 2016-08-10 | 成都聚汇才科技有限公司 | Audio signal processing system based on audio frequency modulation circuit |
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