CN202634684U - Frequency modulator having noise suppression circuit - Google Patents
Frequency modulator having noise suppression circuit Download PDFInfo
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- CN202634684U CN202634684U CN 201220056945 CN201220056945U CN202634684U CN 202634684 U CN202634684 U CN 202634684U CN 201220056945 CN201220056945 CN 201220056945 CN 201220056945 U CN201220056945 U CN 201220056945U CN 202634684 U CN202634684 U CN 202634684U
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Abstract
The utility model discloses a frequency modulator having a noise suppression circuit. The frequency modulator having the noise suppression circuit includes a tuned circuit, a frequency changer circuit, an intermediate-frequency amplification circuit, a noise suppression circuit, a detection circuit, an audio frequency pre-amplification circuit and an audio frequency amplification circuit. The tuned circuit is used for selecting signals of a certain frequency. The frequency changer circuit is used for mixing frequency of the signals selected by the tuned circuit and a local oscillator, thereby obtaining intermediate-frequency signals. The intermediate-frequency amplification circuit is used for amplifying the intermediate-frequency signals obtained by the frequency changer circuit, thereby meeting requirements of the detection circuit. The noise suppression circuit is used for suppressing noises before receiving frequency modulated signals are not received. The detection circuit is used for demodulating audio signals from an audio frequency package and filtering high-frequency signals. The audio frequency pre-amplification circuit is used for performing open-loop pre-amplification of the audio signals output by the detection circuit. The audio frequency amplification circuit is used for performing closed-loop amplification of the audio signals, thereby realizing an aim of driving a loudspeaker. By using the frequency modulator having the noise suppression circuit provided by the utility model, the noises before receiving frequency modulated signals can be suppressed effectively.
Description
Technical field
The utility model relates to noise reduction techniques, relates in particular to the noise suppression circuit that is used for frequency modulation machine.
Background technology
Fig. 1 comprises tuning circuit 101, frequency changer circuit 102, IF amplifier circuit 103, detecting circuit 104, the preparatory amplifying circuit 105 of audio frequency and audio power amplifying circuit 106 for the structure chart of existing frequency modulation machine.Said tuning circuit 101 is in order to choose the signal of some frequencies; Said frequency changer circuit 102 is that tuning signal of selecting and local oscillator are carried out mixing, therefrom obtains intermediate-freuqncy signal; Said IF amplifier circuit 103 is that the intermediate-freuqncy signal that said frequency changer circuit 102 obtains is amplified, to such an extent as to reach the requirement of detecting circuit; Said detecting circuit 104 is to come out the filtering high-frequency signal to audio signal demodulation in the audio pack; The preparatory amplifying circuit 105 of said audio frequency is the audio signal of detection output to be carried out open loop amplify in advance; Said audio power amplifying circuit 106 is audio signal to be carried out closed loop amplify, in the hope of reaching the promotion loud speaker.
The operation principle of existing frequency modulation machine is: the high-frequency signal that antenna receives is chosen through tuning circuit; Then send in the frequency changer circuit with wireless local oscillation frequency and mix through input circuit; Frequency-selecting produces intermediate frequency, and intermediate frequency has only changed the frequency of carrier wave, and audio pack winding thread does not originally change; Intermediate-freuqncy signal can obtain amplifying through IF amplifier circuit better; Amplified IF signal demodulates audio signal and filtering high-frequency signal through detection, after preparatory amplification of audio frequency and power amplification, promotes loud speaker and sounds again.
Existing frequency modulation machine is not when IF amplifier circuit reaches the detecting circuit requirement; When just not receiving FM signal; Have high-frequency signal through said IF amplifier circuit 103 and said detecting circuit 104; Then be input to the preparatory amplifying circuit 105 of said audio frequency and carry out power amplification, make noise let the people be difficult to stand with said audio power amplifying circuit 106.In order to suppress this noise, just noise suppression circuit need be set.
The utility model content
The utility model is intended to solve the deficiency of prior art, and a kind of noise suppression circuit that can suppress noise effectively is provided.
Frequency modulation machine with noise suppression circuit comprises tuning circuit, frequency changer circuit, IF amplifier circuit, noise suppression circuit, detecting circuit, the preparatory amplifying circuit of audio frequency and audio power amplifying circuit:
Said tuning circuit is in order to choose the signal of some frequencies;
Said frequency changer circuit is that tuning signal of choosing and local oscillator are carried out mixing, therefrom obtains intermediate-freuqncy signal;
Said IF amplifier circuit is that the intermediate-freuqncy signal that said frequency changer circuit obtains is amplified, to such an extent as to reach the requirement of detecting circuit;
Said noise suppression circuit is that the noise when not receiving FM signal is suppressed;
Said detecting circuit is to come out the filtering high-frequency signal to audio signal demodulation in the audio pack;
The preparatory amplifying circuit of said audio frequency is the audio signal of detection output to be carried out open loop amplify in advance;
Said audio power amplifying circuit is audio signal to be carried out closed loop amplify, in the hope of reaching the promotion loud speaker.
Said IF amplifier circuit comprises first amplifier, second amplifier, the 3rd amplifier, the 4th amplifier, the 5th amplifier, first electric capacity, second electric capacity, the 3rd electric capacity, the 4th electric capacity, the 5th electric capacity, the 6th electric capacity, the 7th electric capacity, the 8th electric capacity, first resistance, second resistance and the 3rd resistance:
The signal of the said frequency changer circuit output of the positive termination of said first amplifier, negative terminal connects first resistance to anode, and output plus terminal connects second electric capacity, one end, and the output negative terminal connects first electric capacity, one end;
One end of positive termination second electric capacity of said second amplifier, negative terminal connects an end of first electric capacity, and output plus terminal connects the 4th electric capacity one end, and the output negative terminal connects the 3rd electric capacity one end;
One end of positive termination the 4th electric capacity of said the 3rd amplifier, negative terminal connects an end of the 3rd electric capacity, and output plus terminal connects the 6th electric capacity one end and the 3rd resistance one end, and the output negative terminal connects an end of the 5th electric capacity one end and second resistance;
One end of positive termination the 6th electric capacity of said the 4th amplifier, negative terminal connects an end of the 5th electric capacity, and output plus terminal connects the 8th electric capacity one end, and the output negative terminal connects the 7th electric capacity one end;
One end of positive termination the 8th electric capacity of said the 5th amplifier, negative terminal connects an end of the 7th electric capacity, the said detecting circuit of output termination.
The output negative terminal of said first amplifier of one termination of said first electric capacity, the negative terminal of said second amplifier of another termination;
The output plus terminal of said first amplifier of one termination of said second electric capacity, the anode of said second amplifier of another termination;
The output negative terminal of said second amplifier of one termination of said the 3rd electric capacity, the negative terminal of said the 3rd amplifier of another termination;
The output plus terminal of said second amplifier of one termination of said the 4th electric capacity, the anode of said the 3rd amplifier of another termination;
The output negative terminal of said the 3rd amplifier of one termination of said the 5th electric capacity, the negative terminal of said the 4th amplifier of another termination;
The output plus terminal of said the 3rd amplifier of one termination of said the 6th electric capacity, the anode of said the 4th amplifier of another termination;
The output negative terminal of said the 4th amplifier of one termination of said the 7th electric capacity, the negative terminal of said the 5th amplifier of another termination;
The output plus terminal of said the 4th amplifier of one termination of said the 8th electric capacity, the anode of said the 5th amplifier of another termination;
The output of the said frequency changer circuit of said first resistance, one termination and the anode of said first amplifier, the negative terminal of said first amplifier of another termination;
The output negative terminal of said the 3rd amplifier of one termination of said second resistance, said noise suppression circuit of another termination and said the 3rd resistance;
The output plus terminal of said the 3rd amplifier of one termination of said the 3rd resistance, the said noise suppression circuit of another termination and said second resistance.
The internal structure of said first amplifier, second amplifier, the 3rd amplifier, the 4th amplifier and the 5th amplifier all is the same, specifically comprises the 4th resistance, the 5th resistance, the 6th resistance, the 7th resistance, the 8th resistance, the 9th resistance, the tenth resistance, NPN pipe, the 2nd NPN pipe:
One termination reference voltage of said the 4th resistance, an end of said the 5th resistance of another termination and an end of said the 6th resistance;
One end of said the 4th resistance of one termination of said the 5th resistance and an end of said the 6th resistance, the negative terminal input of another termination amplifier and the base stage of said the 2nd NPN pipe;
One end of said the 4th resistance of one termination of said the 6th resistance and an end of said the 5th resistance, the anode input of another termination amplifier and the base stage of said NPN pipe;
One termination power of said the 7th resistance, an end of said the 8th resistance of another termination and an end of said the 9th resistance;
One end of said the 7th resistance of one termination of said the 8th resistance and an end of said the 9th resistance, the collector electrode of the said NPN pipe of another termination and the output of amplifier anode;
One end of said the 7th resistance of one termination of said the 9th resistance and an end of said the 8th resistance, the collector electrode of said the 2nd NPN pipe of another termination and the output of amplifier negative terminal;
The emitter of said NPN pipe of one termination of said the tenth resistance and said the 2nd NPN pipe, other end ground connection; [0039] base stage of said NPN pipe connects the anode input of amplifier and an end of said the 6th resistance; Collector electrode connects the anode output of an end and the amplifier of said the 8th resistance, and emitter connects the emitter of said the 2nd NPN pipe and an end of said the tenth resistance;
The base stage of said the 2nd NPN pipe connects the negative terminal input of amplifier and an end of said the 5th resistance, and collector electrode connects the negative terminal output of an end and the amplifier of said the 9th resistance, and emitter connects the emitter of said NPN pipe and an end of said the tenth resistance.
Said noise suppression circuit comprises the 11 resistance, the 12 resistance, the 13 resistance, the 14 resistance, the 15 resistance, the 16 resistance, the 17 resistance, the 18 resistance, PNP pipe, the 2nd PNP pipe, the 3rd NPN pipe, the 4th NPN pipe, the 5th NPN pipe and the 6th NPN pipe:
One termination power of said the 11 resistance, the collector electrode of the said PNP pipe of another termination;
The emitter of said the 3rd NPN pipe of one termination of said the 12 resistance, other end ground connection;
One termination power of said the 13 resistance, the collector electrode of said the 4th NPN pipe of another termination and the base stage of said the 5th NPN pipe;
The emitter of said the 4th NPN pipe of one termination of said the 14 resistance, other end ground connection;
One termination power of said the 15 resistance, the base stage of an end of said the 17 resistance of another termination and said the 2nd PNP pipe;
One termination power of said the 16 resistance, the emitter of said the 2nd PNP pipe of another termination;
The base stage of one end of said the 15 resistance of one termination of said the 17 resistance and said the 2nd PNP pipe, the collector electrode of said the 5th NPN pipe of another termination;
The collector electrode of said the 2nd PNP pipe of one termination of said the 18 resistance and the base stage of said the 6th NPN pipe;
The base stage of said PNP pipe connects the other end output of IF amplifier circuit, and collector electrode connects the collector electrode and the base stage of said the 3rd NPN pipe, and emitter connects an end of said the 11 resistance;
The base stage of said the 2nd PNP pipe connects an end of said the 15 resistance and an end of said the 17 resistance, and collector electrode connects the base stage of an end and said the 6th NPN pipe of said the 18 resistance, and emitter connects an end of said the 16 resistance;
The base stage of said the 3rd NPN pipe connects the collector electrode of collector electrode and said PNP pipe, and emitter connects an end of said the 12 resistance;
The base stage of said the 4th NPN pipe connects the base stage of said the 3rd NPN pipe, and collector electrode connects the base stage of an end and said the 5th NPN pipe of said the 13 resistance, and emitter connects an end of said the 14 resistance;
The base stage of said the 5th NPN pipe connects an end of said the 13 resistance and the collector electrode of said the 4th NPN pipe, and collector electrode connects an end of said the 17 resistance, grounded emitter;
The collector electrode of said the 2nd PNP pipe of the base stage of said the 6th NPN pipe and an end of said the 18 resistance, collector electrode connects the input of the preparatory amplifying circuit of said audio frequency, grounded emitter.
When the base voltage of said PNP pipe reaches when a PNP plumber is done; Said the 3rd NPN pipe has electric current to pass through, and is mirrored to said the 4th NPN pipe, drags down the base voltage of said the 5th NPN pipe; When low when the 5th NPN plumber is done; The also not conducting of said the 2nd PNP pipe, to such an extent as to said the 6th NPN pipe is not worked, the collector electrode of the 6th NPN pipe is unsettled; When the base voltage of said PNP pipe high when a PNP being managed do not work; Said the 3rd NPN pipe and said the 4th NPN pipe all do not have electric current to pass through; This moment, the base voltage of said the 5th NPN pipe was drawn high, and made the conducting of the 5th NPN pipe degree of depth, and it is very low that the base voltage of managing said the 2nd PNP draws; The base voltage of said the 6th NPN pipe is raise, the collector electrode of the 6th NPN pipe is dragged down.
The preparatory amplifying circuit of said audio frequency is made up of an open loop amplifier; The output of the said detecting circuit of positive termination of open loop amplifier and the output of said noise suppression circuit; The negativing ending grounding of open loop amplifier, the output of open loop amplifier connect the anode input of said audio power amplifying circuit.
Said audio power amplifying circuit comprises closed loop amplifier, the 19 resistance, the 20 resistance, the 21 resistance, the 9th electric capacity and the tenth electric capacity:
The output of the preparatory amplifying circuit of the said audio frequency of positive termination of said power amplifier, negative terminal connects an end of said the 19 resistance and an end of said the 20 resistance, an end of said the 19 resistance of output termination and an end of said the tenth electric capacity;
One termination closed loop amplifier negative terminal of said the 19 resistance, another termination amplifier output;
One termination closed loop amplifier negative terminal of said the 20 resistance, an end of said the tenth electric capacity of another termination;
The negative terminal of the said closed loop amplifier of one termination of said the 21 resistance, an end of another termination the 9th electric capacity;
One end of said the 21 resistance of one termination of said the 9th electric capacity, other end ground connection;
One end of said the 20 resistance of one termination of said the tenth electric capacity, the output of another termination closed loop amplifier.
Utilize the utility model effectively the noise when not receiving FM signal suppress.
Description of drawings
Fig. 1 is the structure chart of existing frequency modulation machine.
Fig. 2 is the structure chart of the frequency modulation machine with noise suppression circuit of the utility model.
Fig. 3 is the circuit diagram of IF amplifier circuit of the frequency modulation machine of the utility model.
Fig. 4 is the circuit diagram of the amplifier of Fig. 3.
Fig. 5 is the circuit diagram of the noise suppression circuit of the utility model.
Fig. 6 is the circuit diagram of preparatory amplifying circuit of the audio frequency of the utility model and audio power amplifying circuit.
Embodiment
Below in conjunction with accompanying drawing the utility model content is further specified.
As shown in Figure 2; For having the frequency modulation machine structure chart of noise suppression circuit, comprise tuning circuit 101, frequency changer circuit 102, IF amplifier circuit 103, noise suppression circuit 107, detecting circuit 104, the preparatory amplifying circuit 105 of audio frequency and audio power amplifying circuit 106:
Said tuning circuit 101 is in order to choose the signal of some frequencies;
Said frequency changer circuit 102 is that the tuning signal of choosing 111 is carried out mixing with local oscillator, therefrom obtains intermediate-freuqncy signal 112;
Said IF amplifier circuit 103 is that the intermediate-freuqncy signal 112 that said frequency changer circuit 102 obtains is amplified, to such an extent as to reach the requirement of detecting circuit 104;
Said noise suppression circuit 107 is that the noise when not receiving FM signal is suppressed;
Said detecting circuit 104 is to come out the filtering high-frequency signal to audio signal demodulation in the audio pack;
The preparatory amplifying circuit 105 of said audio frequency is the audio signal 114 of detection output to be carried out open loop amplify in advance;
Said audio power amplifying circuit 106 is audio signal to be carried out closed loop amplify, in the hope of reaching the promotion loud speaker.
As shown in Figure 3, be the circuit diagram of IF amplifier circuit 103.
IF amplifier circuit 103 comprises first amplifier 301, second amplifier 302, the 3rd amplifier 303, the 4th amplifier 304, the 5th amplifier 305, first electric capacity 309, second electric capacity 312, the 3rd electric capacity 315, the 4th electric capacity 318, the 5th electric capacity 321, the 6th electric capacity 324, the 7th electric capacity 327, the 8th electric capacity 330, first resistance 306, second resistance 332 and the 3rd resistance 333:
The signal 112 of said frequency changer circuit 102 outputs of the positive termination of said first amplifier 301, negative terminal connect first resistance 306 to anode, and output plus terminal 311 connects second electric capacity, 312 1 ends, and output negative terminal 308 connects first electric capacity, 309 1 ends;
One end of positive termination second electric capacity 312 of said second amplifier 302, negative terminal connects an end of first electric capacity 309, and output plus terminal 317 connects the 4th electric capacity 318 1 ends, and output negative terminal 314 connects the 3rd electric capacity 315 1 ends;
One end of positive termination the 4th electric capacity 318 of said the 3rd amplifier 303; Negative terminal connects an end of the 3rd electric capacity 315; Output plus terminal 323 connects the 6th electric capacity 324 1 ends and the 3rd resistance 333 1 ends, and output negative terminal 320 connects an end of the 5th electric capacity 321 1 ends and second resistance 332;
One end of positive termination the 6th electric capacity 324 of said the 4th amplifier 304, negative terminal connects an end of the 5th electric capacity 321, and output plus terminal 329 connects the 8th electric capacity 330 1 ends, and output negative terminal 326 connects the 7th electric capacity 327 1 ends;
One end of positive termination the 8th electric capacity 330 of said the 5th amplifier 305, negative terminal connects an end of the 7th electric capacity 327, and output 113 connects said detecting circuit 104.
The output negative terminal 308 of said first amplifier 301 of one termination of said first electric capacity 309, the negative terminal 310 of said second amplifier 302 of another termination;
The output plus terminal 311 of said first amplifier 301 of one termination of said second electric capacity 312, the anode 313 of said second amplifier 302 of another termination;
The output negative terminal 314 of said second amplifier 302 of one termination of said the 3rd electric capacity 315, the negative terminal 316 of said the 3rd amplifier 303 of another termination;
The output plus terminal 317 of said second amplifier 302 of one termination of said the 4th electric capacity 318, the anode 319 of said the 3rd amplifier 303 of another termination;
The output negative terminal 320 of said the 3rd amplifier 303 of one termination of said the 5th electric capacity 321, the negative terminal 322 of said the 4th amplifier 304 of another termination;
The output plus terminal 323 of said the 3rd amplifier 303 of one termination of said the 6th electric capacity 324, the anode 325 of said the 4th amplifier 304 of another termination;
The output negative terminal 326 of said the 4th amplifier 304 of one termination of said the 7th electric capacity 327, the negative terminal 328 of said the 5th amplifier 305 of another termination;
The output plus terminal 329 of said the 4th amplifier 304 of one termination of said the 8th electric capacity 330, the anode 331 of said the 5th amplifier 305 of another termination;
The output 112 of the said frequency changer circuit 102 of said first resistance, 306 1 terminations and the anode of said first amplifier 301, the negative terminal 307 of said first amplifier 301 of another termination;
The output negative terminal 320 of said the 3rd amplifier 303 of one termination of said second resistance 332, said noise suppression circuit 107 of another termination and said the 3rd resistance 333;
The output plus terminal 323 of said the 3rd amplifier 303 of one termination of said the 3rd resistance 333, said noise suppression circuit 107 of another termination and said second resistance 332.
The internal structure of said first amplifier 301, second amplifier 302, the 3rd amplifier 303, the 4th amplifier 304 and the 5th amplifier 305 all is the same; Internal circuit is as shown in Figure 4, specifically comprises the 4th resistance 404, the 5th resistance 406, the 6th resistance 407, the 7th resistance 408, the 8th resistance 410, the 9th resistance 411, the tenth resistance 415, NPN pipe the 412, the 2nd NPN pipe 413:
One termination reference voltage 403 of said the 4th resistance 404, an end of said the 5th resistance 406 of another termination and an end of said the 6th resistance 407;
One end of said the 4th resistance 404 of one termination of said the 5th resistance 406 and an end of said the 6th resistance 407, the negative terminal input 402 of another termination amplifier and the base stage of said the 2nd NPN pipe 413;
One end of said the 4th resistance 404 of one termination of said the 6th resistance 407 and an end of said the 5th resistance 406, the anode input 401 of another termination amplifier and the base stage of said NPN pipe 412;
One termination power VCC of said the 7th resistance 408, an end of said the 8th resistance 410 of another termination and an end of said the 9th resistance 411;
One end of said the 7th resistance 408 of one termination of said the 8th resistance 410 and an end of said the 9th resistance 411, the collector electrode of the said NPN pipe 412 of another termination and amplifier anode output 416;
One end of said the 7th resistance 408 of one termination of said the 9th resistance 411 and an end of said the 8th resistance 410, the collector electrode of said the 2nd NPN pipe 413 of another termination and amplifier negative terminal output 417;
The emitter of said NPN pipe 412 of one termination of said the tenth resistance 415 and said the 2nd NPN pipe 413, other end ground connection;
The base stage of said NPN pipe 412 connects the anode input 401 of amplifier and an end of said the 6th resistance 407; Collector electrode connects the anode output 416 of an end and the amplifier of said the 8th resistance 410, and emitter connects the emitter of said the 2nd NPN pipe 413 and an end of said the tenth resistance 415;
The base stage of said the 2nd NPN pipe 413 connects the negative terminal input 402 of amplifier and an end of said the 5th resistance 406; Collector electrode connects the negative terminal output 417 of an end and the amplifier of said the 9th resistance 411, and emitter connects the emitter of said NPN pipe 412 and an end of said the tenth resistance 415.
As shown in Figure 5, be the circuit diagram of said noise suppression circuit 107.
Said noise suppression circuit 107 comprises the 11 resistance the 502, the 12 resistance the 505, the 13 resistance the 508, the 14 resistance the 506, the 15 resistance the 512, the 16 resistance the 513, the 17 resistance the 511, the 18 resistance 515, PNP pipe the 501, the 2nd PNP pipe the 514, the 3rd NPN pipe the 504, the 4th NPN pipe the 507, the 5th NPN pipe the 510 and the 6th NPN pipe 516:
One termination power VCC of said the 11 resistance 502, the collector electrode of the said PNP pipe 501 of another termination;
The emitter of said the 3rd NPN pipe 504 of one termination of said the 12 resistance 505, other end ground connection;
One termination power VCC of said the 13 resistance 508, the collector electrode of said the 4th NPN pipe 507 of another termination and the base stage of said the 5th NPN pipe 510;
The emitter of said the 4th NPN pipe 507 of one termination of said the 14 resistance 506, other end ground connection;
One termination power VCC of said the 15 resistance 512, the base stage of an end of said the 17 resistance 511 of another termination and said the 2nd PNP pipe 514;
One termination power VCC of said the 16 resistance 513, the emitter of said the 2nd PNP pipe 514 of another termination;
The base stage of one end of said the 15 resistance 512 of one termination of said the 17 resistance 511 and said the 2nd PNP pipe 514, the collector electrode of said the 5th NPN pipe 510 of another termination;
The collector electrode of said the 2nd PNP pipe 514 of one termination of said the 18 resistance 515 and the base stage of said the 6th NPN pipe 516;
The base stage of said PNP pipe 501 connects the other end output of IF amplifier circuit 103, and collector electrode connects the collector electrode and the base stage of said the 3rd NPN pipe 504, and emitter connects an end of said the 11 resistance 502;
The base stage of said the 2nd PNP pipe 514 connects an end of said the 15 resistance 512 and an end of said the 17 resistance 511; Collector electrode connects the base stage of an end and said the 6th NPN pipe 516 of said the 18 resistance 515, and emitter connects an end of said the 16 resistance 513;
The base stage of said the 3rd NPN pipe 504 connects the collector electrode of collector electrode and said PNP pipe 501, and emitter connects an end of said the 12 resistance 505;
The base stage of said the 4th NPN pipe 507 connects the base stage of said the 3rd NPN pipe 504, and collector electrode connects the base stage of an end and said the 5th NPN pipe 510 of said the 13 resistance 508, and emitter connects an end of said the 14 resistance 506;
The base stage of said the 5th NPN pipe 510 connects an end of said the 13 resistance 508 and the collector electrode of said the 4th NPN pipe 507, and collector electrode connects an end of said the 17 resistance 511, grounded emitter;
The collector electrode of said the 2nd PNP pipe 514 of the base stage of said the 6th NPN pipe 516 and an end of said the 18 resistance 515, collector electrode connects the input of the preparatory amplifying circuit 105 of said audio frequency, grounded emitter.
When the base voltage of said PNP pipe 501 reaches can make 501 work of a PNP pipe time; Said the 3rd NPN pipe 504 has electric current to pass through, and is mirrored to said the 4th NPN pipe 507, drags down the base voltage of said the 5th NPN pipe 510; When low when the 5th NPN pipe 510 is worked; The also not conducting of said the 2nd PNP pipe, to such an extent as to said the 6th NPN pipe 516 is not worked, the collector electrode of the 6th NPN pipe 516 is unsettled; When the base voltage of said PNP pipe 501 high to making a PNP manage 501 when not working; Said the 3rd NPN pipe 504 does not all have electric current to pass through with said the 4th NPN pipe 507; This moment, said the 5th NPN pipe 510 base voltage was drawn high, and made the 5th NPN manage 510 degree of depth conductings, managed very low that 514 base voltage draws to said the 2nd PNP; The base voltage of said the 6th NPN pipe 516 is raise, the collector electrode of the 6th NPN pipe 516 is dragged down.
As shown in Figure 6, be the circuit diagram of preparatory amplifying circuit of audio frequency and audio power amplifying circuit.
The preparatory amplifying circuit 105 of said audio frequency is made up of an open loop amplifier 601; The output of the said detecting circuit 104 of positive termination of open loop amplifier 601 and the output of said noise suppression circuit 107; The negativing ending grounding of open loop amplifier 601, the output of open loop amplifier 601 connect the anode input of said audio power amplifying circuit 106.
Said audio power amplifying circuit 106 comprises closed loop amplifier the 602, the 19 resistance the 603, the 20 resistance the 604, the 21 resistance 606, the 9th electric capacity 607 and the tenth electric capacity 605:
The output 115 of the preparatory amplifying circuit 105 of the said audio frequency of positive termination of said power amplifier 602; Negative terminal connects an end of said the 19 resistance 603 and an end of said the 20 resistance 604, and output 116 connects an end of said the 19 resistance 603 and an end of said the tenth electric capacity 605;
One termination closed loop amplifier, 602 negative terminals of said the 19 resistance 603, another termination amplifier 602 outputs;
One termination closed loop amplifier, 602 negative terminals of said the 20 resistance 604, an end of said the tenth electric capacity 605 of another termination;
The negative terminal of the said closed loop amplifier 602 of one termination of said the 21 resistance 606, an end of another termination the 9th electric capacity 607;
One end of said the 21 resistance 606 of one termination of said the 9th electric capacity 607, other end ground connection;
One end of said the 20 resistance 604 of one termination of said the tenth electric capacity 605, the output of another termination closed loop amplifier 602.
The utility model discloses provides a kind of noise suppression circuit and method thereof that is used for frequency modulation machine, and illustrates and describes the embodiment and the effect of the utility model.What should be understood that is: the foregoing description is just to the explanation of the utility model, rather than to the restriction of the utility model, any innovation and creation that do not exceed in the utility model connotation scope all fall within the utility model protection range.
Claims (6)
1. the frequency modulation machine that has noise suppression circuit is characterized in that comprising tuning circuit, frequency changer circuit, IF amplifier circuit, noise suppression circuit, detecting circuit, the preparatory amplifying circuit of audio frequency and audio power amplifying circuit:
Said tuning circuit is in order to choose the signal of some frequencies;
Said frequency changer circuit is that tuning signal of choosing and local oscillator are carried out mixing, therefrom obtains intermediate-freuqncy signal;
Said IF amplifier circuit is that the intermediate-freuqncy signal that said frequency changer circuit obtains is amplified, to such an extent as to reach the requirement of detecting circuit;
Said noise suppression circuit is that the noise when not receiving FM signal is suppressed;
Said detecting circuit is to come out the filtering high-frequency signal to audio signal demodulation in the audio pack;
The preparatory amplifying circuit of said audio frequency is the audio signal of detection output to be carried out open loop amplify in advance;
Said audio power amplifying circuit is audio signal to be carried out closed loop amplify, in the hope of reaching the promotion loud speaker.
2. the frequency modulation machine with noise suppression circuit as claimed in claim 1 is characterized in that IF amplifier circuit comprises first amplifier, second amplifier, the 3rd amplifier, the 4th amplifier, the 5th amplifier, first electric capacity, second electric capacity, the 3rd electric capacity, the 4th electric capacity, the 5th electric capacity, the 6th electric capacity, the 7th electric capacity, the 8th electric capacity, first resistance, second resistance and the 3rd resistance:
The signal of the said frequency changer circuit output of the positive termination of said first amplifier, negative terminal connects first resistance to anode, and output plus terminal connects second electric capacity, one end, and the output negative terminal connects first electric capacity, one end;
One end of positive termination second electric capacity of said second amplifier, negative terminal connects an end of first electric capacity, and output plus terminal connects the 4th electric capacity one end, and the output negative terminal connects the 3rd electric capacity one end;
One end of positive termination the 4th electric capacity of said the 3rd amplifier, negative terminal connects an end of the 3rd electric capacity, and output plus terminal connects the 6th electric capacity one end and the 3rd resistance one end, and the output negative terminal connects an end of the 5th electric capacity one end and second resistance;
One end of positive termination the 6th electric capacity of said the 4th amplifier, negative terminal connects an end of the 5th electric capacity, and output plus terminal connects the 8th electric capacity one end, and the output negative terminal connects the 7th electric capacity one end;
One end of positive termination the 8th electric capacity of said the 5th amplifier, negative terminal connects an end of the 7th electric capacity, the said detecting circuit of output termination;
The output negative terminal of said first amplifier of one termination of said first electric capacity, the negative terminal of said second amplifier of another termination;
The output plus terminal of said first amplifier of one termination of said second electric capacity, the anode of said second amplifier of another termination;
The output negative terminal of said second amplifier of one termination of said the 3rd electric capacity, the negative terminal of said the 3rd amplifier of another termination;
The output plus terminal of said second amplifier of one termination of said the 4th electric capacity, the anode of said the 3rd amplifier of another termination;
The output negative terminal of said the 3rd amplifier of one termination of said the 5th electric capacity, the negative terminal of said the 4th amplifier of another termination;
The output plus terminal of said the 3rd amplifier of one termination of said the 6th electric capacity, the anode of said the 4th amplifier of another termination;
The output negative terminal of said the 4th amplifier of one termination of said the 7th electric capacity, the negative terminal of said the 5th amplifier of another termination;
The output plus terminal of said the 4th amplifier of one termination of said the 8th electric capacity, the anode of said the 5th amplifier of another termination;
The output of the said frequency changer circuit of said first resistance, one termination and the anode of said first amplifier, the negative terminal of said first amplifier of another termination;
The output negative terminal of said the 3rd amplifier of one termination of said second resistance, said noise suppression circuit of another termination and said the 3rd resistance;
The output plus terminal of said the 3rd amplifier of one termination of said the 3rd resistance, the said noise suppression circuit of another termination and said second resistance.
3. the frequency modulation machine with noise suppression circuit as claimed in claim 2 is characterized in that first amplifier, second amplifier, the 3rd amplifier, the 4th amplifier and the 5th amplifier comprise the 4th resistance, the 5th resistance, the 6th resistance, the 7th resistance, the 8th resistance, the 9th resistance, the tenth resistance, NPN pipe, the 2nd NPN pipe:
One termination reference voltage of said the 4th resistance, an end of said the 5th resistance of another termination and an end of said the 6th resistance;
One end of said the 4th resistance of one termination of said the 5th resistance and an end of said the 6th resistance, the negative terminal input of another termination amplifier and the base stage of said the 2nd NPN pipe;
One end of said the 4th resistance of one termination of said the 6th resistance and an end of said the 5th resistance, the anode input of another termination amplifier and the base stage of said NPN pipe;
One termination power of said the 7th resistance, an end of said the 8th resistance of another termination and an end of said the 9th resistance;
One end of said the 7th resistance of one termination of said the 8th resistance and an end of said the 9th resistance, the collector electrode of the said NPN pipe of another termination and the output of amplifier anode;
One end of said the 7th resistance of one termination of said the 9th resistance and an end of said the 8th resistance, the collector electrode of said the 2nd NPN pipe of another termination and the output of amplifier negative terminal;
The emitter of said NPN pipe of one termination of said the tenth resistance and said the 2nd NPN pipe, other end ground connection;
The base stage of said NPN pipe connects the anode input of amplifier and an end of said the 6th resistance, and collector electrode connects the anode output of an end and the amplifier of said the 8th resistance, and emitter connects the emitter of said the 2nd NPN pipe and an end of said the tenth resistance;
The base stage of said the 2nd NPN pipe connects the negative terminal input of amplifier and an end of said the 5th resistance, and collector electrode connects the negative terminal output of an end and the amplifier of said the 9th resistance, and emitter connects the emitter of said NPN pipe and an end of said the tenth resistance.
4. the frequency modulation machine with noise suppression circuit as claimed in claim 1 is characterized in that noise suppression circuit comprises the 11 resistance, the 12 resistance, the 13 resistance, the 14 resistance, the 15 resistance, the 16 resistance, the 17 resistance, the 18 resistance, PNP pipe, the 2nd PNP pipe, the 3rd NPN pipe, the 4th NPN pipe, the 5th NPN pipe and the 6th NPN pipe:
One termination power of said the 11 resistance, the collector electrode of the said PNP pipe of another termination;
The emitter of said the 3rd NPN pipe of one termination of said the 12 resistance, other end ground connection;
One termination power of said the 13 resistance, the collector electrode of said the 4th NPN pipe of another termination and the base stage of said the 5th NPN pipe;
The emitter of said the 4th NPN pipe of one termination of said the 14 resistance, other end ground connection;
One termination power of said the 15 resistance, the base stage of an end of said the 17 resistance of another termination and said the 2nd PNP pipe;
One termination power of said the 16 resistance, the emitter of said the 2nd PNP pipe of another termination;
The base stage of one end of said the 15 resistance of one termination of said the 17 resistance and said the 2nd PNP pipe, the collector electrode of said the 5th NPN pipe of another termination;
The collector electrode of said the 2nd PNP pipe of one termination of said the 18 resistance and the base stage of said the 6th NPN pipe;
The base stage of said PNP pipe connects the other end output of IF amplifier circuit, and collector electrode connects the collector electrode and the base stage of said the 3rd NPN pipe, and emitter connects an end of said the 11 resistance;
The base stage of said the 2nd PNP pipe connects an end of said the 15 resistance and an end of said the 17 resistance, and collector electrode connects the base stage of an end and said the 6th NPN pipe of said the 18 resistance, and emitter connects an end of said the 16 resistance;
The base stage of said the 3rd NPN pipe connects the collector electrode of collector electrode and said PNP pipe, and emitter connects an end of said the 12 resistance;
The base stage of said the 4th NPN pipe connects the base stage of said the 3rd NPN pipe, and collector electrode connects the base stage of an end and said the 5th NPN pipe of said the 13 resistance, and emitter connects an end of said the 14 resistance;
The base stage of said the 5th NPN pipe connects an end of said the 13 resistance and the collector electrode of said the 4th NPN pipe, and collector electrode connects an end of said the 17 resistance, grounded emitter;
The collector electrode of said the 2nd PNP pipe of the base stage of said the 6th NPN pipe and an end of said the 18 resistance, collector electrode connects the input of the preparatory amplifying circuit of said audio frequency, grounded emitter.
5. the frequency modulation machine with noise suppression circuit as claimed in claim 1; It is characterized in that the preparatory amplifying circuit of audio frequency comprises the open loop amplifier; The output of the said detecting circuit of positive termination of open loop amplifier and the output of said noise suppression circuit; The negativing ending grounding of open loop amplifier, the output of open loop amplifier connect the anode input of said audio power amplifying circuit.
6. the frequency modulation machine with noise suppression circuit as claimed in claim 1 is characterized in that audio power amplifying circuit comprises closed loop amplifier, the 19 resistance, the 20 resistance, the 21 resistance, the 9th electric capacity and the tenth electric capacity:
The output of the preparatory amplifying circuit of the said audio frequency of positive termination of said power amplifier, negative terminal connects an end of said the 19 resistance and an end of said the 20 resistance, an end of said the 19 resistance of output termination and an end of said the tenth electric capacity;
One termination closed loop amplifier negative terminal of said the 19 resistance, another termination amplifier output;
One termination closed loop amplifier negative terminal of said the 20 resistance, an end of said the tenth electric capacity of another termination;
The negative terminal of the said closed loop amplifier of one termination of said the 21 resistance, an end of another termination the 9th electric capacity;
One end of said the 21 resistance of one termination of said the 9th electric capacity, other end ground connection;
One end of said the 20 resistance of one termination of said the tenth electric capacity, the output of another termination closed loop amplifier.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201220056945 CN202634684U (en) | 2012-02-20 | 2012-02-20 | Frequency modulator having noise suppression circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201220056945 CN202634684U (en) | 2012-02-20 | 2012-02-20 | Frequency modulator having noise suppression circuit |
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| Publication Number | Publication Date |
|---|---|
| CN202634684U true CN202634684U (en) | 2012-12-26 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 201220056945 Expired - Fee Related CN202634684U (en) | 2012-02-20 | 2012-02-20 | Frequency modulator having noise suppression circuit |
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| CN (1) | CN202634684U (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106331257A (en) * | 2016-08-19 | 2017-01-11 | 青岛海信移动通信技术股份有限公司 | Noise elimination method and apparatus, and communication device |
-
2012
- 2012-02-20 CN CN 201220056945 patent/CN202634684U/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106331257A (en) * | 2016-08-19 | 2017-01-11 | 青岛海信移动通信技术股份有限公司 | Noise elimination method and apparatus, and communication device |
| CN106331257B (en) * | 2016-08-19 | 2019-07-02 | 青岛海信移动通信技术股份有限公司 | A kind of method of canceling noise, device and communication equipment |
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