CN107911097A - A kind of bandpass filter - Google Patents
A kind of bandpass filter Download PDFInfo
- Publication number
- CN107911097A CN107911097A CN201810007530.7A CN201810007530A CN107911097A CN 107911097 A CN107911097 A CN 107911097A CN 201810007530 A CN201810007530 A CN 201810007530A CN 107911097 A CN107911097 A CN 107911097A
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- resistance
- operational amplifier
- capacitance
- bandpass filter
- output terminal
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- 238000001914 filtration Methods 0.000 claims abstract description 22
- 230000002452 interceptive effect Effects 0.000 abstract description 5
- 230000000694 effects Effects 0.000 abstract description 4
- 230000005236 sound signal Effects 0.000 description 4
- 230000005611 electricity Effects 0.000 description 3
- 230000000087 stabilizing effect Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H11/00—Networks using active elements
- H03H11/02—Multiple-port networks
- H03H11/04—Frequency selective two-port networks
- H03H11/12—Frequency selective two-port networks using amplifiers with feedback
- H03H11/1217—Frequency selective two-port networks using amplifiers with feedback using a plurality of operational amplifiers
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- Networks Using Active Elements (AREA)
Abstract
The invention discloses a kind of bandpass filter, it is characterised in that：Including second order high-pass filtering circuit, the second-order low-pass filter circuit being connected with second order high-pass filtering circuit；The second order high-pass filtering circuit includes operational amplifier A 1, one end is grounded as capacitance C1, the P pole that signal input part, the other end are connected after capacitance C2 with the cathode of operational amplifier A 1 after resistance R3, the diode D1 that N poles are connected with the tie point of capacitance C1 and capacitance C2 etc..The present invention can be isolated the interfering noise outside setting range, effectively eliminate interfering noise, improve communication effect.
Description
Technical field
The present invention relates to a kind of wave filter, in particular to a kind of bandpass filter.
Background technology
Wave filter can filter out other frequency signals beyond specific frequency, it is widely used in communication field, to carry
High speech quality.Such as generally use wave filter filters out other interference signals beyond sound of speaking in telephonic communication system,
To improve speech quality.But it is not good enough to interference signal filter effect for wave filter used by existing communication system, leads
Speech quality is caused to be unable to reach demand.
The content of the invention
It is an object of the invention to overcome conventional filter to the imperfect defect of interference signal filter effect, there is provided a kind of
Bandpass filter.
The purpose of the present invention is achieved through the following technical solutions：A kind of bandpass filter, including second order high-pass filtering circuit,
The second-order low-pass filter circuit being connected with second order high-pass filtering circuit；The second order high-pass filtering circuit includes operational amplifier
A1, capacitance C1, the P poles that one end is connected as signal input part, the other end after capacitance C2 with the cathode of operational amplifier A 1
The diode D1 that ground connection, N poles are connected with the tie point of capacitance C1 and capacitance C2 after resistance R3, is serially connected in the N of diode D1
Resistance R2 between the output terminal of pole and operational amplifier A 1, is serially connected in the output terminal of operational amplifier A 1 and the P of diode D1
Resistance R4 between pole, and one end is connected with the cathode of operational amplifier A 1, the resistance R1 of other end ground connection；The computing
The output terminal of amplifier A1 is connected with second-order low-pass filter circuit, its anode is connected with the P poles of diode D1.
Further, the second-order low-pass filter circuit includes operational amplifier A 2, and one end is defeated with operational amplifier A 1
The resistance R5 that outlet is connected, the other end is connected after resistance R7 with the cathode of operational amplifier A 2, one end and resistance R5 and
The capacitance C4 that the tie point of resistance R7 is connected, the other end is connected with the output terminal of operational amplifier A 2, with capacitance C4 phases simultaneously
The resistance R8 of connection, one end is connected with the cathode of operational amplifier A 2, the capacitance C3 of other end ground connection, is in parallel with capacitance C3
Resistance R6, and the resistance R9 that one end is connected with the output terminal of operational amplifier A 2, the other end is grounded after resistance R10；Institute
The anode for stating operational amplifier P2 is connected with the tie point of resistance R9 and resistance R10, its output terminal is as signal output part.
The centre frequency of the second order high-pass filtering circuit isThe second-order low-pass filter
The centre frequency of circuit is
The gain A of the second order high-pass filtering circuitF1Equal to the gain A of second-order low-pass filter circuitF2, i.e.,：The gain A of the bandpass filterF=AF1AF2。
The frequency filtering of the bandpass filter is 300~3000Hz.
The present invention compared with the prior art, has the following advantages and beneficial effect：The present invention can be by outside setting range
Interfering noise is isolated, and effectively eliminates interfering noise, improves communication effect.
Brief description of the drawings
Fig. 1 is the overall structure diagram of the present invention.
Embodiment
The present invention is described in further detail with reference to embodiment, but embodiments of the present invention are not limited to
This.
Embodiment
As shown in Figure 1, the bandpass filter of the present invention, including second order high-pass filtering circuit, with second order high-pass filtering circuit
The second-order low-pass filter circuit being connected.The frequency filtering of the bandpass filter is 300~3000Hz, it can effectively be filtered
Interfering noise and retain the audio signal spoken so that telephonic communication system output sound become apparent from.
Specifically, the second order high-pass filtering circuit includes operational amplifier A 1, capacitance C1, capacitance C2, resistance R1, resistance
R2, resistance R3, resistance R4 and diode D1.
During connection, one end of capacitance C1 with as signal input part, the other end after capacitance C2 with operational amplifier A 1
Cathode be connected.The P poles of diode D1 are grounded after resistance R3, N poles are connected with the tie point of capacitance C1 and capacitance C2.Electricity
Resistance R2 is serially connected between the N poles of diode D1 and the output terminal of operational amplifier A 1.Resistance R4 is serially connected in operational amplifier A 1
Between output terminal and the P poles of diode D1.One end of resistance R1 is connected with the cathode of operational amplifier A 1, other end ground connection.
The output terminal of the operational amplifier A 1 is connected with second-order low-pass filter circuit, its anode is connected with the P poles of diode D1.
Signal input inputs to operational amplifier A 1 after coming in after capacitance C1 and capacitance C2 are filtered, the operation amplifier
Device A1, capacitance C1, capacitance C2, resistance R4 and resistance R3 are collectively forming high-pass filter；The operational amplifier A 1 is negative-feedback,
It can be with the gain of stabilizing circuit.The centre frequency of the second order high-pass filtering circuit isIn this reality
Apply in example, the capacitance of capacitance C1 and capacitance C2 is that the resistance value of 0.068 μ F, resistance R1 and resistance R2 are 8.2K Ω；By upper
Stating formula can draw, the centre frequency f of second order high-pass filtering circuit in the present embodiment1=286Hz.In addition, the type of diode D1
Number be 14001, the resistance value of resistance R4 is 27K Ω, and the resistance value of resistance R3 is 47K Ω, the model OP07 of operational amplifier A 1.Fortune
The audio signal for calculating amplifier A1 outputs is input to second-order low-pass filter circuit.
As shown in Figure 1, the second-order low-pass filter circuit includes operational amplifier A 2, resistance R5, resistance R7, resistance R6, electricity
Hinder R8, resistance R9, resistance R10, capacitance C3 and capacitance C4.During specific connection, one end and the operational amplifier A 1 of resistance R5
Output terminal be connected, cathode of the other end with operational amplifier A 2 after resistance R7 is connected.One end of capacitance C4 and resistance
The tie point of R5 and resistance R7 are connected, the other end is connected with the output terminal of operational amplifier A 2.Resistance R8 and capacitance C4 phases
It is in parallel.One end of capacitance C3 is connected with the cathode of operational amplifier A 2, other end ground connection.Resistance R6 is in parallel with capacitance C3.
One end of resistance R9 is connected with the output terminal of operational amplifier A 2, the other end is grounded after resistance R10.The operational amplifier
The anode of P2 is connected with the tie point of resistance R9 and resistance R10, its output terminal then output terminal as signal.
The audio signal that operational amplifier A 1 exports inputs to operational amplifier A 2, while electricity after resistance R5 and resistance R7
Audio signal can be filtered by holding C3 and capacitance C4；The operational amplifier A 2, resistance R5, resistance R7, capacitance C3, resistance R6,
Capacitance C4 and resistance R8 are collectively forming low-pass filter.Operational amplifier A 2 is also negative-feedback, it can be with the increasing of stabilizing circuit
Benefit.The centre frequency of the second-order low-pass filter circuit isIn the present embodiment, resistance R5 and
The resistance value of resistance R7 is that the capacitance of 8.2K Ω, capacitance C3 and capacitance C4 are 0.0068 μ F；It can be drawn by above-mentioned formula, this reality
Apply the centre frequency f of second-order low-pass filter circuit in example2=2856Hz.In addition, the resistance value of resistance R6 is 10K Ω, resistance R8
Resistance value be 1K Ω, the resistance value of resistance R9 is 27K Ω, and the resistance value of resistance R10 is 47K Ω, the model of operational amplifier A 2
OP07。
Obtained by above-mentioned, the cutoff frequency of the bandwidth-limited circuit of the present embodiment is 286Hz~2856Hz, so that effectively
Interference signal beyond one's voice in speech frequency signal is isolated, improves speech quality.
In addition, the gain A of the second order high-pass filtering circuitF1Equal to the gain A of second-order low-pass filter circuitF2, i.e.,：The gain A of the bandwidth-limited circuitF=AF1AF2。
As described above, the present invention can be realized well.
Claims (5)
- A kind of 1. bandpass filter, it is characterised in that：Including second order high-pass filtering circuit, it is connected with second order high-pass filtering circuit Second-order low-pass filter circuit；The second order high-pass filtering circuit includes operational amplifier A 1, and one end is used as signal input part, another Capacitance C1, the P pole that one end is connected after capacitance C2 with the cathode of operational amplifier A 1 is grounded after resistance R3, N poles and capacitance The diode D1 that C1 is connected with the tie point of capacitance C2, is serially connected in the N poles of diode D1 and the output terminal of operational amplifier A 1 Between resistance R2, the resistance R4 being serially connected between the output terminal of operational amplifier A 1 and the P poles of diode D1, and one end with The cathode of operational amplifier A 1 is connected, the resistance R1 of other end ground connection；The output terminal of the operational amplifier A 1 is low with second order Bandpass filter circuit is connected, its anode is connected with the P poles of diode D1.
- A kind of 2. bandpass filter according to claim 1, it is characterised in that：The second-order low-pass filter circuit includes fortune Calculate amplifier A2, one end is connected with the output terminal of operational amplifier A 1, the other end after resistance R7 with operational amplifier A 2 The resistance R5 that cathode is connected, one end is connected with the tie point of resistance R5 and resistance R7, the other end and operational amplifier A 2 The capacitance C4 that output terminal is connected, the resistance R8 being in parallel with capacitance C4, one end is connected, separately with the cathode of operational amplifier A 2 One end ground connection capacitance C3, the resistance R6 being in parallel with capacitance C3, and one end be connected with the output terminal of operational amplifier A 2, The resistance R9 that the other end is grounded after resistance R10；The anode of the operational amplifier P2 and the tie point of resistance R9 and resistance R10 It is connected, its output terminal is as signal output part.
- A kind of 3. bandpass filter according to claim 2, it is characterised in that：The center of the second order high-pass filtering circuit Frequency isThe centre frequency of the second-order low-pass filter circuit is
- A kind of 4. bandpass filter according to claim 3, it is characterised in that：The gain of the second order high-pass filtering circuit AF1Equal to the gain A of second-order low-pass filter circuitF2, i.e.,：The gain A of the bandpass filterF= AF1AF2。
- A kind of 5. bandpass filter according to claim 4, it is characterised in that：The frequency filtering of the bandpass filter is 300~3000Hz.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810007530.7A CN107911097A (en) | 2018-01-04 | 2018-01-04 | A kind of bandpass filter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810007530.7A CN107911097A (en) | 2018-01-04 | 2018-01-04 | A kind of bandpass filter |
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| Publication Number | Publication Date |
|---|---|
| CN107911097A true CN107911097A (en) | 2018-04-13 |
Family
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201810007530.7A Pending CN107911097A (en) | 2018-01-04 | 2018-01-04 | A kind of bandpass filter |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109178250A (en) * | 2018-08-28 | 2019-01-11 | 上海海事大学 | A kind of Intelligent lifesaving circle with speech recognition |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH02183612A (en) * | 1989-01-09 | 1990-07-18 | Murata Mfg Co Ltd | Active filter circuit |
| CN105232040A (en) * | 2015-09-29 | 2016-01-13 | 武汉工程大学 | Muscle fatigue detection system and method |
| CN106209018A (en) * | 2016-08-01 | 2016-12-07 | 合肥佳瑞林电子技术有限公司 | A kind of high-power band filter of ground radar |
-
2018
- 2018-01-04 CN CN201810007530.7A patent/CN107911097A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH02183612A (en) * | 1989-01-09 | 1990-07-18 | Murata Mfg Co Ltd | Active filter circuit |
| CN105232040A (en) * | 2015-09-29 | 2016-01-13 | 武汉工程大学 | Muscle fatigue detection system and method |
| CN106209018A (en) * | 2016-08-01 | 2016-12-07 | 合肥佳瑞林电子技术有限公司 | A kind of high-power band filter of ground radar |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109178250A (en) * | 2018-08-28 | 2019-01-11 | 上海海事大学 | A kind of Intelligent lifesaving circle with speech recognition |
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Application publication date: 20180413 |