CN204090126U - Audio frequency PWM circuit and stereo set - Google Patents
Audio frequency PWM circuit and stereo set Download PDFInfo
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- CN204090126U CN204090126U CN201420467089.8U CN201420467089U CN204090126U CN 204090126 U CN204090126 U CN 204090126U CN 201420467089 U CN201420467089 U CN 201420467089U CN 204090126 U CN204090126 U CN 204090126U
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Abstract
The utility model discloses a kind of audio frequency PWM circuit, this circuit comprises operating voltage input, audio signal input end, audio frequency PWM modulation signal output, the first reference voltage generating circuit, triangular signal circuit for generating and PWM circuit; The power input of the first reference voltage generating circuit, triangular signal circuit for generating and PWM circuit is all connected with operating voltage input; The output of the first reference voltage generating circuit and audio signal input end are all connected with the first input end of PWM circuit; The output of triangular signal circuit for generating is connected with the second input of PWM circuit; The output of PWM circuit is connected with audio frequency PWM modulation signal output.The utility model also provides a kind of stereo set.The operating frequency of the utility model audio frequency PWM circuit is adjustable, and the utility model also has the advantage that cost is low and EMC design difficulty is low.
Description
Technical field
The utility model relates to electronic technology field, particularly a kind of audio frequency PWM circuit and stereo set.
Background technology
At present, in order to the tonequality meeting stereo set full acoustic frequency scope ensures (20HZ-20KHZ, the audiorange that people's ear can be heard), the modulation base wave frequency of existing stereo set sound intermediate frequency PWM circuit is all at more than 300KHZ.Because higher operating frequency represents more sampled data, better to the reduction degree of audio signal, therefore, multichannel, high operate frequency are the developing direction of the voice modulation scheme of current stereo set.
But, in some specific use occasions, the audio frequency as active woofer (woofer, woofer) is 60HZ, it does not need too high operating frequency, and only needs process single-channel data (multichannel can cause the waste on cost); And for example some wireless non-isolated woofer, it also only needs a lower operating frequency (40KHZ-100KHZ), and higher operating frequency can make the very large (EMC of EMC intractability, Electro Magnetic Compatibility, Electro Magnetic Compatibility refers to that equipment or system meet the requirements in its electromagnetic environment and runs the ability of intolerable electromagnetic interference of not producing any equipment in its environment).
Utility model content
Main purpose of the present utility model is to provide a kind of low cost, EMC design difficulty is low and the audio frequency PWM circuit that operating frequency is adjustable.
For achieving the above object, the utility model provides a kind of audio frequency PWM circuit, described audio frequency PWM circuit comprises operating voltage input, audio signal input end, audio frequency PWM modulation signal output, for generation of the first reference voltage generating circuit of a reference voltage signal, for generation of the triangular signal circuit for generating of a triangular signal, and for described triangular signal and described reference voltage signal being carried out contrast to produce a PWM fundamental signal and the PWM circuit audio signal that described audio signal input end inputs being carried out to PWM, wherein,
The power input of described first reference voltage generating circuit, triangular signal circuit for generating and PWM circuit is all connected with described operating voltage input; The output of described first reference voltage generating circuit and described audio signal input end are all connected with the first input end of described PWM circuit; The output of described triangular signal circuit for generating is connected with the second input of described PWM circuit; The output of described PWM circuit is connected with described audio frequency PWM modulation signal output.
Preferably, described triangular signal circuit for generating comprises constant-current source circuit, charging capacitor, NMOS tube, the second reference voltage generating circuit, the first voltage comparator and the first resistance; Wherein,
The input of described constant-current source circuit is connected with described operating voltage input, and the output of described constant-current source circuit is connected with the first end of described charging capacitor; Second end ground connection of described charging capacitor; The drain electrode of described NMOS tube is connected with the first end of described charging capacitor, the source ground of described NMOS tube, and the grid of described NMOS tube is connected with the output of described first voltage comparator; The positive input terminal of described first voltage comparator is connected with the drain electrode of described NMOS tube, the negative input end of described first voltage comparator is connected with the output of described second reference voltage generating circuit, the power end of described first voltage comparator is connected with described operating voltage input, the ground end ground connection of described first voltage comparator; The input of described second reference voltage generating circuit is connected with described operating voltage input.
Preferably, described constant-current source circuit comprises the second resistance, the 3rd resistance, the 4th resistance and PNP triode; Wherein,
The first end of described second resistance is connected with described operating voltage input, and the second end of described second resistance is connected with the base stage of described PNP triode and the first end of described 3rd resistance respectively; Second end ground connection of described 3rd resistance; The emitter of described PNP triode is connected with described operating voltage input through described 4th resistance, and the collector electrode of described PNP triode is connected with the first end of described charging capacitor.
Preferably, described second reference voltage generating circuit comprises the 5th resistance and the 6th resistance; Wherein,
The first end of described 5th resistance is connected with described operating voltage input, and the second end of described 5th resistance is connected with the negative input end of described first voltage comparator and the first end of described 6th resistance respectively; Second end ground connection of described 6th resistance.
Preferably, described PWM circuit comprises the second voltage comparator, the 7th resistance, the 8th resistance and capacitance; Wherein,
The first end of described capacitance is connected with the positive input terminal of described second voltage comparator, and the second end of described capacitance is connected with described audio signal input end, the positive input terminal of described second voltage comparator is also connected with the output of described first reference voltage generating circuit, the negative input end of described second voltage comparator is connected with the drain electrode of described NMOS tube, the output of described second voltage comparator is connected with described audio frequency PWM modulation signal output, the output of described second voltage comparator is also connected with described operating voltage input through described 7th resistance, the power end of described second voltage comparator is connected with described operating voltage input, the ground end ground connection of described second voltage comparator, the ground end of described second voltage comparator is also connected with described audio signal input end through described 8th resistance.
Preferably, described first reference voltage generating circuit comprises the 9th resistance and the tenth resistance; Wherein,
The first end of described 9th resistance is connected with described operating voltage input, and the second end of described 9th resistance is connected with the positive input terminal of described second voltage comparator and the first end of described tenth resistance respectively; Second end ground connection of described tenth resistance.
Preferably, the resistance of described 5th resistance equals the resistance of described 6th resistance.
Preferably, the resistance value ratio of described 9th resistance and described tenth resistance is 3:1.
Preferably, described first voltage comparator and described second voltage comparator are two voltage comparators in the integrated IC of twin voltage comparator.
In addition, for achieving the above object, the utility model also provides a kind of stereo set, described stereo set comprises audio frequency PWM circuit, described audio frequency PWM circuit comprises operating voltage input, audio signal input end, audio frequency PWM modulation signal output, for generation of the first reference voltage generating circuit of a reference voltage signal, for generation of the triangular signal circuit for generating of a triangular signal, and for described triangular signal and described reference voltage signal being carried out contrast to produce a PWM fundamental signal and the PWM circuit audio signal that described audio signal input end inputs being carried out to PWM, wherein,
The power input of described first reference voltage generating circuit, triangular signal circuit for generating and PWM circuit is all connected with described operating voltage input; The output of described first reference voltage generating circuit and described audio signal input end are all connected with the first input end of described PWM circuit; The output of described triangular signal circuit for generating is connected with the second input of described PWM circuit; The output of described PWM circuit is connected with described audio frequency PWM modulation signal output.
The audio frequency PWM circuit that the utility model provides, comprises operating voltage input, audio signal input end, audio frequency PWM modulation signal output, the first reference voltage generating circuit for generation of a reference voltage signal, the triangular signal circuit for generating for generation of a triangular signal and for triangular signal and reference voltage signal being carried out contrasting to produce a PWM fundamental signal and the PWM circuit audio signal that audio signal input end inputs being carried out to PWM; Wherein, the power input of the first reference voltage generating circuit, triangular signal circuit for generating and PWM circuit is all connected with operating voltage input; The output of the first reference voltage generating circuit and audio signal input end are all connected with the first input end of PWM circuit; The output of triangular signal circuit for generating is connected with the second input of PWM circuit; The output of PWM circuit is connected with audio frequency PWM modulation signal output.The operating frequency of the utility model audio frequency PWM circuit is adjustable, and the utility model also has the advantage that cost is low and EMC design difficulty is low.Meanwhile, the utility model audio frequency PWM circuit also has structure advantage that is simple and that easily realize.
Accompanying drawing explanation
Fig. 1 is the electrical block diagram of the utility model audio frequency PWM circuit preferred embodiment;
Fig. 2 is the oscillogram of the PWM fundamental signal that the triangular signal that produces of the utility model audio frequency PWM circuit preferred embodiment intermediate cam ripple signal generating circuit and PWM circuit produce when audio signal input end no audio signal inputs.
The realization of the utility model object, functional characteristics and advantage will in conjunction with the embodiments, are described further with reference to accompanying drawing.
Embodiment
Should be appreciated that specific embodiment described herein only in order to explain the utility model, and be not used in restriction the utility model.
The utility model provides a kind of audio frequency PWM circuit.
With reference to the electrical block diagram that Fig. 1, Fig. 1 are the preferred embodiments of the utility model audio frequency PWM circuit.
This audio frequency PWM circuit comprises operating voltage input 101, audio signal input end 102, audio frequency PWM modulation signal output 103, first reference voltage generating circuit 104, triangular signal circuit for generating 105 and PWM circuit 106.
Wherein, the power input of described first reference voltage generating circuit 104, triangular signal circuit for generating 105 and PWM circuit 106 is all connected with described operating voltage input 101; Output and the described audio signal input end 102 of described first reference voltage generating circuit 104 are all connected with the first input end of described PWM circuit 106; The output of described triangular signal circuit for generating 105 is connected with the second input of described PWM circuit 106; The output of described PWM circuit 106 is connected with described audio frequency PWM modulation signal output 103.
Above-mentioned first reference voltage generating circuit 104, for generation of a reference voltage signal to the first input end of PWM circuit 106; Above-mentioned triangular signal circuit for generating 105, for generation of a triangular signal to the second input of PWM circuit 106; Said PWM modulation circuit 106, the reference voltage signal produced for the triangular signal that produced by triangular signal circuit for generating 105 and described first reference voltage generating circuit 104 carries out contrasting to produce a PWM fundamental signal and carrying out PWM to the audio signal that described audio input end 102 inputs.
Particularly, above-mentioned triangular signal circuit for generating 105 comprises constant-current source circuit 1051, charging capacitor C1, NMOS tube Q2, the second reference voltage generating circuit 1052, first voltage comparator U1A and the first resistance R1;
Wherein, the input of described constant-current source circuit 1051 is the power input of triangular signal circuit for generating 105, is connected with described operating voltage input 101, and the output of described constant-current source circuit 1051 is connected with the first end of described charging capacitor C1; The second end ground connection of described charging capacitor C1; The drain electrode of described NMOS tube Q2 is connected with the first end of described charging capacitor C1, the source ground of described NMOS tube Q2, and the grid of described NMOS tube Q2 is connected with the output of described first voltage comparator U1A; The positive input terminal of described first voltage comparator U1A is connected with the drain electrode of described NMOS tube Q2, the negative input end of described first voltage comparator U1A is connected with the output of described second reference voltage generating circuit 1052, the power end of described first voltage comparator U1A is connected with described operating voltage input 101, the ground end ground connection of described first voltage comparator U1A; The input of described second reference voltage generating circuit 1052 is connected with described operating voltage input 101;
Above-mentioned constant-current source circuit 1051 comprises the second resistance R2, the 3rd resistance R3, the 4th resistance R4 and PNP triode Q1.Wherein, the first end of described second resistance R2 is connected with described operating voltage input 101, and second end of described second resistance R2 is connected with the base stage of described PNP triode Q1 and the first end of described 3rd resistance R3 respectively; The second end ground connection of described 3rd resistance R3; The emitter of described PNP triode Q1 is connected with described operating voltage input 101 through described 4th resistance R4, and the collector electrode of described PNP triode Q1 is connected with the first end of described charging capacitor C1;
Above-mentioned second reference voltage generating circuit 1052 comprises the 5th resistance R5 and the 6th resistance R6.Wherein, the first end of described 5th resistance R5 is connected with described operating voltage input 101, and second end of described 5th resistance R5 is connected with the negative input end of described first voltage comparator U1A and the first end of described 6th resistance R6 respectively; The second end ground connection of described 6th resistance R6.
Said PWM modulation circuit 106 comprises the second voltage comparator U1B, the 7th resistance R7, the 8th resistance R8 and capacitance C2.Wherein, the first end of described capacitance C2 is connected with the positive input terminal (i.e. the first input end of said PWM modulation circuit 106) of described second voltage comparator U1B, and second end of described capacitance C2 is connected with described audio signal input end 102, the positive input terminal of described second voltage comparator U1B is also connected with the output of above-mentioned first reference voltage generating circuit 104, the negative input end (i.e. the second input of said PWM modulation circuit 106) of described second voltage comparator U1B is connected with the drain electrode (i.e. the output of triangular signal circuit for generating 105) of described NMOS tube, the output of described second voltage comparator U1B is connected with described audio frequency PWM modulation signal output 103, the output of described second voltage comparator U1B is also connected with described operating voltage input 101 through described 7th resistance R7, the power end (i.e. the power input of PWM circuit 106) of described second voltage comparator U1B is connected with described operating voltage input 101, the ground end ground connection of described second voltage comparator U1B, the ground end of described second voltage comparator U1B is also connected with described audio signal input end 102 through described 8th resistance R8.
Above-mentioned first reference voltage generating circuit 104 comprises the 9th resistance R9 and the tenth resistance R10.Wherein, the first end (i.e. the power input of the first reference voltage generating circuit 104) of described 9th resistance R9 is connected with described operating voltage input 101, and second end of described 9th resistance R9 is connected with the positive input terminal of described second voltage comparator U1B and the first end of described tenth resistance R10 respectively; The second end ground connection of described tenth resistance R10.
In the present embodiment, above-mentioned first voltage comparator U1A and described second voltage comparator U1B is two voltage comparators in the integrated IC of twin voltage comparator, and in the present embodiment, the model of the integrated IC of this twin voltage comparator is LM393.Particularly, 3rd pin of the integrated IC LM393 of the corresponding twin voltage comparator of positive input terminal of above-mentioned first voltage comparator U1A, 2nd pin of the integrated IC LM393 of the corresponding twin voltage comparator of negative input end of above-mentioned first voltage comparator U1A, the 1st pin of the integrated IC LM393 of the corresponding twin voltage comparator of output of above-mentioned first voltage comparator U1A; 5th pin of the integrated IC LM393 of the corresponding twin voltage comparator of positive input terminal of above-mentioned second voltage comparator U1B, 6th pin of the integrated IC LM393 of the corresponding twin voltage comparator of negative input end of above-mentioned second voltage comparator U1B, the 7th pin of the integrated IC LM393 of the corresponding twin voltage comparator of output of above-mentioned second voltage comparator U1B; 8th pin of the integrated IC LM393 of the corresponding twin voltage comparator of above-mentioned first voltage comparator U1A's and above-mentioned second voltage comparator U1B's power end, the 4th pin of the integrated IC LM393 of corresponding twin voltage comparator is held on above-mentioned first voltage comparator U1A's and above-mentioned second voltage comparator U1B's ground.
In the present embodiment, the voltage of operating voltage input 101 is 12V; The resistance of the 5th resistance R5 equals the resistance of described 6th resistance R6; The resistance value ratio of described 9th resistance R9 and described tenth resistance R10 is 3:1.
The operation principle of the present embodiment audio frequency PWM circuit specifically describes as follows: after operating voltage input 101 powers on, constant-current source circuit 1051 couples of charging capacitor C1 charge, by the second reference voltage generating circuit 1052 that the 5th resistance R5 and the 6th resistance R6 forms, produce the negative input end of reference voltage to a first voltage comparator U1A, the positive input terminal of the first voltage comparator U1A is connected with charging capacitor C1, after the voltage charging of charging capacitor C1 reaches the reference voltage that the second reference voltage generating circuit 1052 produces, the output of the first voltage comparator U1A exports high level, make NMOS tube Q2 conducting, make the voltage of charging capacitor C1 by zero setting again, and then repeat above-mentioned charging process and voltage zeroing process again, thus in positive input terminal (the i.e. drain electrode of NMOS tube Q2 of the first voltage comparator U1A, 3rd pin of corresponding twin voltage comparator integrated IC LM393) produce a series of triangular signal, this triangular signal that the positive input terminal of the first voltage comparator U1A produces is directly inputted into the negative input end (the 6th pin of the integrated IC LM393 of corresponding twin voltage comparator) of the second voltage comparator U1B.The present embodiment audio frequency PWM circuit according to the different demands to operating frequency, by the capacitance of change charging capacitor C1 or the resistance of the 4th resistance R4, just can reach the operating frequency that design is wanted.The present embodiment designs a central point voltage (i.e. the positive input terminal of the second voltage comparator U1B will input reference voltage) by the first reference voltage generating circuit 104, when audio signal input end 102 does not have input audio signal, the central point voltage (reference voltage) that the triangular signal of the negative input end (the 6th pin of the integrated IC LM393 of corresponding twin voltage comparator) of the second voltage comparator U1B and the first reference voltage generating circuit 104 produce compares, the PWM fundamental signal (i.e. square-wave signal) that a duty ratio is 50% is exported at the output (the 7th pin of the integrated IC LM393 of corresponding twin voltage comparator) of the second voltage comparator U1B, this duty ratio is the fundamental frequency operating frequency that the operating frequency of the PWM fundamental signal of 50% is the modulation of the present embodiment audio frequency PWM circuit, capacitance C2 in the present embodiment is the capacitance of audio signal, the audio signal that audio signal input end 102 inputs affects at the positive input terminal of the second voltage comparator U1B the reference voltage that the first reference voltage generating circuit 104 produces, thus change the duty ratio of the PWM waveform of the output of the second voltage comparator U1B, thus the PWM modulation signal obtaining corresponding audio signal exports from audio frequency PWM modulation signal output 103.
In addition, it should be noted that, the present embodiment audio frequency PWM circuit is in order to ensure the static noiselessness effect (can export the PWM fundamental signal that a duty ratio is 50% at the output of the second voltage comparator U1B) when audio signal input end 102 no audio signal inputs, and the resistance of the 5th resistance R5 must equal the resistance of described 6th resistance R6; The resistance value ratio of described 9th resistance R9 and described tenth resistance R10 is necessary for 3:1.In other embodiments, the resistance value ratio of the 5th resistance R5 and the 6th resistance R6 and the 9th resistance R9 and the tenth resistance R10 changed along with the duty ratio of PWM fundamental signal.
With reference to the oscillogram that Fig. 2, Fig. 2 are the PWM fundamental signals that the triangular signal that produces of the utility model audio frequency PWM circuit preferred embodiment intermediate cam ripple signal generating circuit and PWM circuit produce when audio signal input end no audio signal inputs.
In the present embodiment, when the resistance of the 5th resistance R5 equals the resistance of described 6th resistance R6, and the resistance value ratio of described 9th resistance R9 and described tenth resistance R10 is when being 3:1, the triangular signal that above-mentioned triangular signal circuit for generating 105 produces and the duty ratio that PWM circuit 106 exports when audio signal input end 102 no audio signal inputs be the oscillogram of the PWM fundamental signal of 50% as shown in Figure 2.In figure, VCC represents the voltage of operating voltage input 101, and Vout represents said PWM modulation fundamental signal.
The audio frequency PWM circuit that the present embodiment provides, comprises operating voltage input, audio signal input end, audio frequency PWM modulation signal output, the first reference voltage generating circuit for generation of a reference voltage signal, the triangular signal circuit for generating for generation of a triangular signal and for triangular signal and reference voltage signal being carried out contrasting to produce a PWM fundamental signal and the PWM circuit audio signal that audio signal input end inputs being carried out to PWM; Wherein, the power input of the first reference voltage generating circuit, triangular signal circuit for generating and PWM circuit is all connected with operating voltage input; The output of the first reference voltage generating circuit and audio signal input end are all connected with the first input end of PWM circuit; The output of triangular signal circuit for generating is connected with the second input of PWM circuit; The output of PWM circuit is connected with audio frequency PWM modulation signal output.The operating frequency of the present embodiment audio frequency PWM circuit is adjustable thus reduction EMC design difficulty; Meanwhile, the present embodiment audio frequency PWM circuit also has structure advantage that is simple and that easily realize.
The utility model also provides a kind of stereo set, and this stereo set comprises audio frequency PWM circuit, and modular structure and the circuit structure of this audio frequency PWM circuit can refer to above-described embodiment, do not repeat them here.Naturally, the stereo set due to the present embodiment have employed the technical scheme of above-mentioned audio frequency PWM circuit, and therefore this stereo set has all beneficial effects of above-mentioned audio frequency PWM circuit.
These are only preferred embodiment of the present utility model; not thereby the scope of the claims of the present utility model is limited; every utilize the utility model specification and accompanying drawing content to do equivalent structure or equivalent flow process conversion; or be directly or indirectly used in other relevant technical fields, be all in like manner included in scope of patent protection of the present utility model.
Claims (10)
1. an audio frequency PWM circuit, it is characterized in that, comprising operating voltage input, audio signal input end, audio frequency PWM modulation signal output, the first reference voltage generating circuit for generation of a reference voltage signal, the triangular signal circuit for generating for generation of a triangular signal and for described triangular signal and described reference voltage signal being carried out contrasting to produce a PWM fundamental signal and the PWM circuit audio signal that described audio signal input end inputs being carried out to PWM; Wherein,
The power input of described first reference voltage generating circuit, triangular signal circuit for generating and PWM circuit is all connected with described operating voltage input; The output of described first reference voltage generating circuit and described audio signal input end are all connected with the first input end of described PWM circuit; The output of described triangular signal circuit for generating is connected with the second input of described PWM circuit; The output of described PWM circuit is connected with described audio frequency PWM modulation signal output.
2. audio frequency PWM circuit as claimed in claim 1, it is characterized in that, described triangular signal circuit for generating comprises constant-current source circuit, charging capacitor, NMOS tube, the second reference voltage generating circuit, the first voltage comparator and the first resistance; Wherein,
The input of described constant-current source circuit is connected with described operating voltage input, and the output of described constant-current source circuit is connected with the first end of described charging capacitor; Second end ground connection of described charging capacitor; The drain electrode of described NMOS tube is connected with the first end of described charging capacitor, the source ground of described NMOS tube, and the grid of described NMOS tube is connected with the output of described first voltage comparator; The positive input terminal of described first voltage comparator is connected with the drain electrode of described NMOS tube, the negative input end of described first voltage comparator is connected with the output of described second reference voltage generating circuit, the power end of described first voltage comparator is connected with described operating voltage input, the ground end ground connection of described first voltage comparator; The input of described second reference voltage generating circuit is connected with described operating voltage input.
3. audio frequency PWM circuit as claimed in claim 2, it is characterized in that, described constant-current source circuit comprises the second resistance, the 3rd resistance, the 4th resistance and PNP triode; Wherein,
The first end of described second resistance is connected with described operating voltage input, and the second end of described second resistance is connected with the base stage of described PNP triode and the first end of described 3rd resistance respectively; Second end ground connection of described 3rd resistance; The emitter of described PNP triode is connected with described operating voltage input through described 4th resistance, and the collector electrode of described PNP triode is connected with the first end of described charging capacitor.
4. audio frequency PWM circuit as claimed in claim 2 or claim 3, it is characterized in that, described second reference voltage generating circuit comprises the 5th resistance and the 6th resistance; Wherein,
The first end of described 5th resistance is connected with described operating voltage input, and the second end of described 5th resistance is connected with the negative input end of described first voltage comparator and the first end of described 6th resistance respectively; Second end ground connection of described 6th resistance.
5. audio frequency PWM circuit as claimed in claim 4, it is characterized in that, described PWM circuit comprises the second voltage comparator, the 7th resistance, the 8th resistance and capacitance; Wherein,
The first end of described capacitance is connected with the positive input terminal of described second voltage comparator, and the second end of described capacitance is connected with described audio signal input end, the positive input terminal of described second voltage comparator is also connected with the output of described first reference voltage generating circuit, the negative input end of described second voltage comparator is connected with the drain electrode of described NMOS tube, the output of described second voltage comparator is connected with described audio frequency PWM modulation signal output, the output of described second voltage comparator is also connected with described operating voltage input through described 7th resistance, the power end of described second voltage comparator is connected with described operating voltage input, the ground end ground connection of described second voltage comparator, the ground end of described second voltage comparator is also connected with described audio signal input end through described 8th resistance.
6. audio frequency PWM circuit as claimed in claim 5, it is characterized in that, described first reference voltage generating circuit comprises the 9th resistance and the tenth resistance; Wherein,
The first end of described 9th resistance is connected with described operating voltage input, and the second end of described 9th resistance is connected with the positive input terminal of described second voltage comparator and the first end of described tenth resistance respectively; Second end ground connection of described tenth resistance.
7. audio frequency PWM circuit as claimed in claim 4, it is characterized in that, the resistance of described 5th resistance equals the resistance of described 6th resistance.
8. audio frequency PWM circuit as claimed in claim 6, it is characterized in that, the resistance value ratio of described 9th resistance and described tenth resistance is 3:1.
9. audio frequency PWM circuit as claimed in claim 5, it is characterized in that, described first voltage comparator and described second voltage comparator are two voltage comparators in the integrated IC of twin voltage comparator.
10. a stereo set, is characterized in that, comprises the audio frequency PWM circuit according to any one of claim 1 to 9.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106374835A (en) * | 2016-10-14 | 2017-02-01 | 北京无线电计量测试研究所 | Constant-current ionization excitation circuit and control method |
| CN107306126A (en) * | 2016-04-25 | 2017-10-31 | 中兴通讯股份有限公司 | PWM generation circuit |
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2014
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107306126A (en) * | 2016-04-25 | 2017-10-31 | 中兴通讯股份有限公司 | PWM generation circuit |
| CN106374835A (en) * | 2016-10-14 | 2017-02-01 | 北京无线电计量测试研究所 | Constant-current ionization excitation circuit and control method |
| CN106374835B (en) * | 2016-10-14 | 2019-02-15 | 北京无线电计量测试研究所 | A kind of constant current ionization energizing circuit and control method |
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