CN203225713U - Tunable-frequency band-pass filter for audio frequency near-field payment - Google Patents
Tunable-frequency band-pass filter for audio frequency near-field payment Download PDFInfo
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- CN203225713U CN203225713U CN 201320176488 CN201320176488U CN203225713U CN 203225713 U CN203225713 U CN 203225713U CN 201320176488 CN201320176488 CN 201320176488 CN 201320176488 U CN201320176488 U CN 201320176488U CN 203225713 U CN203225713 U CN 203225713U
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- pass filter
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Abstract
The utility model discloses a tunable-frequency band-pass filter for audio frequency near-field payment. The tunable-frequency band-pass filter includes a first filter circuit, a second filter circuit and a third filter circuit that are sequentially connected in series. The first filter circuit comprises a first amplifier, a first resistor, a third resistor, a fourth resistor and a first coaxial potentiometer; the second filter circuit includes a second amplifier, a fifth resistor, a sixth resistor, a seventh resistor, a second coaxial potentiometer and a first capacitor; and the third filter circuit comprises a third amplifier, an eighth resistor and a second capacitor. According to the utility model, the two coaxial potentiometers are employed respectively to adjust input voltage of the second filter circuit and input voltage of the third filter circuit so as to adjust center frequency of the band-pass filter. Under the premise that the Q value of the circuit is not affected, the tunable-frequency band-pass filter for audio frequency near-field payment enables narrow bandwidth and adjustable frequency, and exhibits good anti-interference performance.
Description
Technical field
The utility model relates to a kind of band pass filter, relates in particular to a kind of frequency adjustable band pass filter for the payment of audio frequency near field.
Background technology
Audio frequency near field payment technology be the applicant's a kind of utilization of proposing and applying for a patent closely audio frequency transmission information to finish the technology of payment function, its audio frequency R-T unit that utilizes conventional equipment such as mobile phone to carry is realized payment, has the advantage that payment is quick, easily implement, easily popularize.In the payment technology of audio frequency near field, receipts at audio frequency, all need use band pass filter in the process of sending out, though traditional band pass filter has without inductance, volume is little, in light weight, the open-loop voltage gain of integrated transporting discharging and input impedance are all very high, output impedance is low again, also have advantages such as certain voltage amplification and buffering effect after constituting power filter, but because of its Q value (being quality factor) can't do very big, what just cause also that its passband width can't do is very narrow, having caused this filter is not fine to the selectivity of frequency, frequency is difficult to regulate, neither be very strong to the inhibition ability of interference signal.
The utility model content
The purpose of this utility model provides a kind of frequency adjustable band pass filter for the payment of audio frequency near field with regard to being in order to address the above problem.
The utility model is achieved through the following technical solutions above-mentioned purpose:
Frequency adjustable band pass filter for the payment of audio frequency near field described in the utility model, comprise first filter circuit of series connection successively, second filter circuit and the 3rd filter circuit, described first filter circuit comprises first amplifier, first resistance, the 3rd resistance, the 4th resistance and first gang potentiometer, first end of described first resistance is connected with the negative input of described first amplifier and first end of described the 3rd resistance respectively, second end of described the 3rd resistance is connected with the output of described first amplifier and first end of first gang potentiometer respectively, and second end of described first gang potentiometer is connected with first end of described the 4th resistance; Described second filter circuit comprises second amplifier, the 5th resistance, the 6th resistance, the 7th resistance, second gang potentiometer and first electric capacity, first end of described the 5th resistance is connected with the sliding end of described first gang potentiometer, second end of described the 5th resistance respectively with the negative input of described second amplifier, first end of described the 6th resistance is connected with first end of described first electric capacity, second end of described the 6th resistance, second end of described first electric capacity, first end of the output of described second amplifier and described second gang potentiometer interconnects, and second end of described second gang potentiometer is connected with first end of described the 7th resistance; Described the 3rd filter circuit comprises the 3rd amplifier, the 8th resistance and second electric capacity, first end of described the 8th resistance is connected with the sliding end of described second gang potentiometer, second end of described the 8th resistance is connected with the negative input of described the 3rd amplifier and first end of described second electric capacity respectively, second end of described second electric capacity is connected the electrode input end of described first amplifier with the output of described the 3rd amplifier, the electrode input end of described second amplifier, the electrode input end of described the 3rd amplifier, second end of described the 4th resistance and second end of described the 7th resistance interconnect; The output of described the 3rd amplifier is connected with first end of described first resistance with second resistance series connection back; Second end of described first resistance is the electrode input end of described band pass filter, the output of described the 3rd amplifier is the cathode output end of described band pass filter, and the electrode input end of described first amplifier is negative input and the cathode output end of described band pass filter simultaneously.
The beneficial effects of the utility model are:
The utility model is regulated the input voltage of second filter circuit and the 3rd filter circuit respectively by adopting two gang potentiometers, thereby the centre frequency that realizes the entire belt bandpass filter is regulated, under the prerequisite that does not influence circuit Q value, make the narrower and frequency adjustable of its bandwidth, and have better anti-jamming capability.
Description of drawings
Fig. 1 is the circuit diagram of frequency adjustable band pass filter described in the utility model;
Fig. 2 is the system architecture diagram of the utility model sound intermediate frequency near field payment system;
Fig. 3 is the circuit structure block diagram of the voice frequency sender of the utility model sound intermediate frequency near field payment system;
Fig. 4 is the circuit structure block diagram of the audio receiver of the utility model sound intermediate frequency near field payment system.
Embodiment
The utility model is described in further detail below in conjunction with accompanying drawing:
As Fig. 2, Fig. 3 and shown in Figure 4, audio frequency near field payment system in the payment technology of audio frequency near field comprise a plurality of (having illustrated 4 among Fig. 2) can be mutually voice frequency terminal by voice communication, this voice frequency terminal can be portable terminals such as mobile phone, also can be fixed terminals such as payment platform.Each voice frequency terminal comprises voice frequency sender and audio receiver, voice frequency sender comprises encoder for convolution codes, modulator, band pass filter, D/A change-over circuit, amplifirer and the loud speaker of series connection successively, the input input Applied Digital data-signal of encoder for convolution codes, the loud speaker output sound signal is used for the information medium as the near field payment; Audio receiver comprises microphone, A/D change-over circuit, band pass filter, demodulator, low pass filter and the convolutional code decoder device of series connection successively, the voice signal that the input input of microphone is transmitted by loud speaker, the output output Applied Digital data-signal of convolutional code decoder device.
As shown in Figure 1, above-mentioned band pass filter comprises first filter circuit of series connection successively, second filter circuit and the 3rd filter circuit, described first filter circuit comprises the first amplifier A1, first resistance R 1, the 3rd resistance R 3, the 4th resistance R 4 and the first gang potentiometer RP1, first end of first resistance R 1 is connected with the negative input of the first amplifier A1 and first end of the 3rd resistance R 3 respectively, second end of the 3rd resistance R 3 is connected with the output of the first amplifier A1 and first end of the first gang potentiometer RP1 respectively, and second end of the first gang potentiometer RP1 is connected with first end of the 4th resistance R 4; Described second filter circuit comprises the second amplifier A2, the 5th resistance R 5, the 6th resistance R 6, the 7th resistance R 7, the second gang potentiometer RP2 and first capacitor C 1, first end of the 5th resistance R 5 is connected with the sliding end of the first gang potentiometer RP1, second end of the 5th resistance R 5 respectively with the negative input of the second amplifier A2, first end of the 6th resistance R 6 is connected with first end of first capacitor C 1, second end of the 6th resistance R 6, second end of first capacitor C 1, first end of the output of the second amplifier A2 and the second gang potentiometer RP2 interconnects, and second end of the second gang potentiometer RP2 is connected with first end of the 7th resistance R 7; Described the 3rd filter circuit comprises the 3rd amplifier A3, the 8th resistance R 8 and second capacitor C 2, first end of the 8th resistance R 8 is connected with the sliding end of the second gang potentiometer RP2, second end of the 8th resistance R 8 is connected with the negative input of the 3rd amplifier A3 and first end of second capacitor C 2 respectively, second end of second capacitor C 2 is connected the electrode input end of the first amplifier A1 with the output of the 3rd amplifier A3, the electrode input end of the second amplifier A2, the electrode input end of the 3rd amplifier A3, second end of second end of the 4th resistance R 4 and the 7th resistance R 7 interconnects; The output of the 3rd amplifier A3 is connected with first end of first resistance R 1 with second resistance R, 2 series connection backs; Second end of first resistance R 1 is the electrode input end of described band pass filter, the output of the 3rd amplifier A3 is the cathode output end of described band pass filter, and the electrode input end of the first amplifier A1 is negative input and the cathode output end of described band pass filter simultaneously; The electrode input end of second end of first resistance R 1 and the first amplifier A1 is formed the input Uin of described band pass filter among the figure, the electrode input end of the output of the 3rd amplifier A3 and the first amplifier A1 is formed the output Uout of described band pass filter, and input Uin and output Uout among the figure all are labeled in positive pole.The above-mentioned first amplifier A1, the second amplifier A2 and the 3rd amplifier A3 are high input impedance type integrated operational amplifier.
Claims (1)
1. one kind is used for the frequency adjustable band pass filter that pay in the audio frequency near field, it is characterized in that: comprise first filter circuit of series connection successively, second filter circuit and the 3rd filter circuit, described first filter circuit comprises first amplifier, first resistance, the 3rd resistance, the 4th resistance and first gang potentiometer, first end of described first resistance is connected with the negative input of described first amplifier and first end of described the 3rd resistance respectively, second end of described the 3rd resistance is connected with the output of described first amplifier and first end of first gang potentiometer respectively, and second end of described first gang potentiometer is connected with first end of described the 4th resistance; Described second filter circuit comprises second amplifier, the 5th resistance, the 6th resistance, the 7th resistance, second gang potentiometer and first electric capacity, first end of described the 5th resistance is connected with the sliding end of described first gang potentiometer, second end of described the 5th resistance respectively with the negative input of described second amplifier, first end of described the 6th resistance is connected with first end of described first electric capacity, second end of described the 6th resistance, second end of described first electric capacity, first end of the output of described second amplifier and described second gang potentiometer interconnects, and second end of described second gang potentiometer is connected with first end of described the 7th resistance; Described the 3rd filter circuit comprises the 3rd amplifier, the 8th resistance and second electric capacity, first end of described the 8th resistance is connected with the sliding end of described second gang potentiometer, second end of described the 8th resistance is connected with the negative input of described the 3rd amplifier and first end of described second electric capacity respectively, second end of described second electric capacity is connected the electrode input end of described first amplifier with the output of described the 3rd amplifier, the electrode input end of described second amplifier, the electrode input end of described the 3rd amplifier, second end of described the 4th resistance and second end of described the 7th resistance interconnect; The output of described the 3rd amplifier is connected with first end of described first resistance with second resistance series connection back; Second end of described first resistance is the electrode input end of described band pass filter, the output of described the 3rd amplifier is the cathode output end of described band pass filter, and the electrode input end of described first amplifier is negative input and the cathode output end of described band pass filter simultaneously.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201320176488 CN203225713U (en) | 2013-04-10 | 2013-04-10 | Tunable-frequency band-pass filter for audio frequency near-field payment |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201320176488 CN203225713U (en) | 2013-04-10 | 2013-04-10 | Tunable-frequency band-pass filter for audio frequency near-field payment |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN203225713U true CN203225713U (en) | 2013-10-02 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 201320176488 Expired - Fee Related CN203225713U (en) | 2013-04-10 | 2013-04-10 | Tunable-frequency band-pass filter for audio frequency near-field payment |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN203225713U (en) |
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2013
- 2013-04-10 CN CN 201320176488 patent/CN203225713U/en not_active Expired - Fee Related
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C17 | Cessation of patent right | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20131002 Termination date: 20140410 |