CN203912166U - Active band stop filter circuit - Google Patents
Active band stop filter circuit Download PDFInfo
- Publication number
- CN203912166U CN203912166U CN201420288638.5U CN201420288638U CN203912166U CN 203912166 U CN203912166 U CN 203912166U CN 201420288638 U CN201420288638 U CN 201420288638U CN 203912166 U CN203912166 U CN 203912166U
- Authority
- CN
- China
- Prior art keywords
- resistor
- circuit
- capacitor
- band
- filter circuit
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 238000001914 filtration Methods 0.000 claims abstract description 34
- 238000007781 pre-processing Methods 0.000 claims abstract description 27
- 230000005236 sound signal Effects 0.000 claims abstract description 25
- 239000003990 capacitor Substances 0.000 claims description 46
- 238000003379 elimination reaction Methods 0.000 claims description 31
- 230000008030 elimination Effects 0.000 claims description 11
- 230000005669 field effect Effects 0.000 claims description 10
- 102100039435 C-X-C motif chemokine 17 Human genes 0.000 claims description 7
- 101000889048 Homo sapiens C-X-C motif chemokine 17 Proteins 0.000 claims description 7
- 230000009977 dual effect Effects 0.000 claims description 3
- 230000004044 response Effects 0.000 abstract description 3
- 238000010586 diagram Methods 0.000 description 7
- 230000003321 amplification Effects 0.000 description 3
- 238000003199 nucleic acid amplification method Methods 0.000 description 3
- 230000002238 attenuated effect Effects 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 230000000903 blocking effect Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
Landscapes
- Amplifiers (AREA)
- Networks Using Active Elements (AREA)
Abstract
The utility model discloses an active band stop filter circuit which comprises a pre-processing circuit, a band stop filter circuit and an amplifying circuit. The pre-processing circuit is used for pre-processing an input audio signal and inputting the signal to the band stop filter circuit. The band stop filter circuit comprises a low pass filter branch and a high pass filter branch, wherein the low pass filter branch and the high pass filter branch are connected in parallel, and the cut-off frequency of the low pass filter branch is lower than the cut-off frequency of the high pass filter branch. The band stop filter circuit is used for carrying out band stop filtering on the audio signal input by the pre-processing circuit. The amplifying circuit is used for amplifying the audio signal after band stop filtering and outputting the signal. According to the technical scheme of the utility model, by adjusting the center frequency of the band stop filter circuit or the attenuation slope of the high pass filter branch, and by adjusting the gain of the circuit, corresponding noise can be effectively filtered out without influencing a frequency response curve, and a clean audio signal is output.
Description
Technical Field
The utility model relates to an electronic circuit technical field, in particular to active band elimination filter circuit.
Background
Noise occurs during the use of an audio pickup device such as a microphone, and it is necessary to design a filter circuit in order to remove the noise.
SUMMERY OF THE UTILITY MODEL
The utility model provides an active band elimination filter circuit to the noise that the filtering used the audio frequency to pick up the equipment in-process and exists.
The utility model discloses an active band elimination filter circuit, include: the device comprises a preprocessing circuit, a band elimination filter circuit and an amplifying circuit; wherein,
the preprocessing circuit is connected with the band-elimination filter circuit and is used for preprocessing an input audio signal and inputting the preprocessed audio signal to the band-elimination filter circuit;
the band-elimination filter circuit is respectively connected with the preprocessing circuit and the amplifying circuit, and comprises a low-pass filter branch and a high-pass filter branch, wherein the low-pass filter branch is connected with the high-pass filter branch in parallel, the cut-off frequency of the low-pass filter branch is lower than that of the high-pass filter branch, and the band-elimination filter circuit is used for performing band-elimination filtering on the audio signal input by the preprocessing circuit;
the amplifying circuit is connected with the band-elimination filter circuit and used for amplifying and outputting the audio signals subjected to band-elimination filtering.
The utility model has the advantages that: the utility model provides an active band elimination filter circuit, to the audio signal of audio frequency pickup equipment input, at first carry out the preliminary treatment, adopt the low pass filter branch road and the high pass filter branch road that connect in parallel to carry out the band elimination filtering processing; then, amplifying the audio signal subjected to band rejection filtering and outputting the audio signal; the utility model discloses an adjust band elimination filter circuit's central frequency, or adjust the decay slope of high pass filtering branch road to and regulating circuit's gain, thereby can filter corresponding noise effectively and do not influence the frequency response curve, export pure audio signal.
Drawings
Fig. 1 is a block diagram of the active band-stop filter circuit of the present invention;
fig. 2 is a schematic circuit diagram of an active band-stop filter circuit according to the present invention;
fig. 3 is a circuit schematic of another active band reject filter circuit of the present invention;
fig. 4 is a schematic circuit diagram of the low-pass filter branch and the high-pass filter branch in the band-stop filter circuit of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer, embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.
The design idea of the utility model is to provide an active band elimination filter circuit, which first pre-processes the audio signal input by the audio pickup device, then carries out band elimination filtering, and then outputs the audio signal after amplification processing; therefore, the purposes of filtering noise and amplifying audio signals without influencing a frequency response curve can be achieved.
As shown in fig. 1, fig. 1 is a block diagram of an active band-stop filter circuit according to the present invention. The embodiment of the utility model provides a pair of active band elimination filter circuit includes: a preprocessing circuit 100, a band-stop filter circuit 200, and an amplification circuit 300, wherein,
the preprocessing circuit 100 is connected to the band-stop filter circuit 200, and is configured to preprocess an audio signal input by an audio pickup device and input the preprocessed audio signal to the band-stop filter circuit 200;
the band-elimination filter circuit 200 is respectively connected with the preprocessing circuit 100 and the amplifying circuit 300, and performs band-elimination filtering on the audio signal input by the preprocessing circuit;
the amplifying circuit 300 is connected to the band-elimination filter circuit 200, and is configured to amplify and output the band-elimination filtered audio signal.
The band-stop filtering circuit in the circuit shown in fig. 1 includes a low-pass filtering branch 201 and a high-pass filtering branch 202, the low-pass filtering branch 201 is connected in parallel with the high-pass filtering branch 202, a cutoff frequency of the low-pass filtering branch 201 is lower than a cutoff frequency of the high-pass filtering branch 202, and the band-stop filtering circuit is used for realizing band-stop filtering.
Referring to fig. 2, fig. 2 is a schematic circuit diagram of an active band-stop filter circuit according to the present invention, including: preprocessing circuit 100, filter circuit 200, amplifier circuit 300.
The preprocessing circuit 100 comprises a first resistor R1, a first capacitor C1, a positive power supply + VCC1, a field effect transistor Q1 and a parallel plate capacitor C0, wherein a first end of the field effect transistor Q1 is a drain electrode D end, a second end is a grid electrode G end, a third end is a source electrode S end, the D end of the field effect transistor Q1 is connected with the first resistor R1 and the first capacitor C1, the other end of the first resistor R1 is connected with the positive power supply + VCC1, the other end of the first capacitor C1 is connected with the band-stop filter circuit 200, the G end of the field effect transistor Q1 is connected with one end of the parallel plate capacitor C0, and the S end of the field effect transistor Q1 and the other end of the parallel plate capacitor C0 are all grounded.
In practical application, the fet Q1 performs impedance transformation and signal amplification on an audio signal provided by the parallel-plate capacitor C0, where the first resistor R1 is a pull-up resistor and provides a proper static operating point for the fet Q1, the positive power supply + VCC1 provides power for the preprocessing circuit, and the first capacitor C1 has the function of blocking direct current and alternating current.
The band-elimination filter circuit 200 is connected to the preprocessing circuit 100 through a first capacitor C1, and the band-elimination filter circuit 200 includes a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, and a reference voltage VREF 1.
Specifically, in the low-pass filtering branch 201, one end of the second resistor R2 is connected to the first capacitor C1, the other end is connected to the third resistor R3, the other end of the third resistor R3 is connected to the non-inverting input terminal of the operational amplifier U1A, one end of the fourth capacitor C4 is connected between the second resistor R2 and the third resistor R3, and the other end is connected to the output terminal of the operational amplifier U1A.
Specifically, in the high-pass filtering branch 202, one end of a second capacitor C2 is connected to the first capacitor C1, the other end is connected to a third capacitor C3, the other end of the third capacitor C3 is connected to the non-inverting input terminal of the operational amplifier U1A, one end of a fourth resistor R4 is connected between the second capacitor C2 and the third capacitor C3, the other end is connected to a reference voltage VREF1, one end of a fifth resistor R5 is connected to the reference voltage VREF1, and the other end is connected to the third resistor R3 and the third capacitor C3 and connected to the non-inverting input terminal of the operational amplifier U1A.
Here, referring to fig. 4, fig. 4 is a schematic circuit diagram of the low-pass filter branch and the high-pass filter branch in the band-stop filter circuit according to the present invention. The second resistor R2, the third resistor R3 and the fourth capacitor C4 form a low-pass filtering branch 201; the second capacitor C2, the third capacitor C3, the fourth resistor R4 and the fifth resistor R5 form a high-pass filter branch 202. The low-pass filtering branch 201 and the high-pass filtering branch 202 are connected in parallel to form a band-stop filtering circuit, and the cutoff frequency of the low-pass filtering branch 201 is lower than that of the high-pass filtering branch 202.
In practical application, an input signal passes through the filter circuit 200 by a preprocessing circuit, the low-pass filter branch 201 can suppress or attenuate a signal higher than the cutoff frequency thereof, the high-pass filter branch 202 can suppress or attenuate a signal lower than the cutoff frequency thereof, the low-pass filtered signal and the high-pass filtered signal are superposed and output at the parallel output ends of the low-pass filter branch 201 and the high-pass filter branch 202, and the signal suppressed or attenuated in both the filter branches does not obtain an output or only outputs the attenuated signal at the output end, so that band-stop filtering processing is realized.
Wherein, the amplifying circuit 300 comprises an operational amplifier U1A, a sixth resistor R6, a seventh resistor R7, a positive voltage source + VCC2, and a reference voltage source VREF2, the first end of the operational amplifier U1A is an output end, the second end is an inverting input end, the third end is a non-inverting input end, the fourth end is a negative power input end, and the eighth end is a positive power input end, specifically, the inverting input end of the operational amplifier U1A is connected to a sixth resistor R6 and a seventh resistor R7, the other end of the sixth resistor R6 is connected to a reference voltage VREF2, the other end of the seventh resistor R7 is connected to the output end of the operational amplifier U1A, the non-inverting input end of the operational amplifier U1A is connected to the third resistor R3, the third capacitor C3 and the fifth resistor R5, the positive power input end of the operational amplifier U1A is connected to a power supply + VCC2, and the negative power input end of the operational amplifier U1A is connected to a negative power supply-.
It should be noted that the active device of the present invention refers to a device (such as the operational amplifier U1A) powered by a power source in a circuit. The operational amplifier U1A is either single power supply or dual power supply.
As shown in fig. 2, when the operational amplifier supplies power to the single power supply, the positive power supply input terminal of the operational amplifier U1A is connected to the positive power supply + VCC2, and the negative power supply input terminal is grounded. As shown in fig. 3, fig. 3 is a schematic circuit diagram of another active band-stop filter circuit according to the present invention. When the operational amplifier supplies power for the double power supplies, the positive power supply input end of the operational amplifier U1A is connected to the positive power supply + VCC2, and the negative power supply input end is connected to the negative power supply-VCC.
Preferably, the reference voltage VREF1 in the high-pass filtering branch 202 and the reference voltage VREF2 in the amplifying circuit 300 are the same reference voltage, that is, VREF1 is VREF2 is VREF; the positive power supply + VCC1 in the preprocessing circuit 100 is the same positive power supply as the positive power supply + VCC2 in the amplifying circuit 300, i.e., + VCC 1-VCC 2-VCC.
In practical applications, the center frequency of the filter circuit 200 can be adjusted by adjusting the resistance values of the resistors R2, R3 or R4 and adjusting the capacitance values of the capacitors C2, C3 or C4. The attenuation slope of the high-pass filter branch 202 is adjusted by adjusting the resistance of the resistor R5 (it should be noted that both R4 and R5 can change the attenuation slope, and the value of R5 is generally changed because the resistance of R4 is limited). The gain of the circuit is adjusted by adjusting the resistance values of the resistors R6 and R7, wherein the circuit gain refers to the gain of the whole active band-stop filter circuit.
Preferably, the resistances of the resistors R2, R3 and R4 satisfy that R2 ═ R3 ═ 2R4, and the capacitances of the capacitors C2, C3 and C4 satisfy that C2 ═ C3 ═ 1/2C 4;
optionally, when the operational amplifier U1A is powered by a single power supply, the reference voltage VREF satisfies VREF 1/2VCC, and when the operational amplifier U1A is powered by a dual power supply, the reference voltage VREF satisfies VREF 0. Wherein the reference voltage VREF is indispensable when U1A is supplying a single power supply.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention shall fall within the protection scope of the present invention.
Claims (10)
1. An active band-stop filter circuit, comprising: the device comprises a preprocessing circuit, a band elimination filter circuit and an amplifying circuit; wherein,
the preprocessing circuit is connected with the band-elimination filter circuit and is used for preprocessing an input audio signal and inputting the preprocessed audio signal to the band-elimination filter circuit;
the band-elimination filter circuit is respectively connected with the preprocessing circuit and the amplifying circuit, and comprises a low-pass filter branch and a high-pass filter branch, wherein the low-pass filter branch is connected with the high-pass filter branch in parallel, the cut-off frequency of the low-pass filter branch is lower than that of the high-pass filter branch, and the band-elimination filter circuit is used for performing band-elimination filtering on the audio signal input by the preprocessing circuit;
the amplifying circuit is connected with the band-elimination filter circuit and used for amplifying and outputting the audio signals subjected to band-elimination filtering.
2. The active band-stop filter circuit of claim 1, wherein the preprocessing circuit at least comprises a field effect transistor Q1, a first positive power supply + VCC1, a first resistor R1 and a first capacitor C1, wherein the audio signal is input to the gate terminal of the field effect transistor Q1, the first resistor R1 is connected between the first positive power supply + VCC1 and the drain terminal of the field effect transistor Q1, the source terminal of the field effect transistor Q1 is grounded, one end of the first capacitor C1 is connected between the first resistor R1 and the drain terminal of the field effect transistor Q1, and the other end is connected to the band-stop filter circuit.
3. The active band-stop filter circuit of claim 1,
the low-pass filtering branch circuit at least comprises a second resistor R2, a third resistor R3 and a fourth capacitor C4, wherein one end of the second resistor R2 is connected with one end of the third resistor R3, the other end of the second resistor R2 is connected to the preprocessing circuit, the other end of the third resistor R3 is connected to the amplifying circuit, one end of the fourth capacitor C4 is connected between the second resistor R2 and the third resistor R3, and the other end of the fourth capacitor C4 is connected to the output end of the amplifying circuit;
the high-pass filtering branch circuit at least comprises a fourth resistor R4, a fifth resistor R5, a second capacitor C2, a third capacitor C3 and a first reference voltage VREF1, wherein one end of the second capacitor C2 is connected with one end of the third capacitor C3, the other end of the second capacitor C2 is connected to the preprocessing circuit, the other end of the third capacitor C3 is connected to the amplifying circuit, one end of the fourth resistor R4 is connected between the second capacitor C2 and the third capacitor C3, the other end of the fourth resistor R4 is connected to the first reference voltage VREF1, one end of the fifth resistor R5 is connected to the first reference voltage VREF1, and the other end of the fifth resistor R5 is connected to the amplifying circuit.
4. The active band-stop filter circuit of claim 3,
the resistances of the second resistor R2, the third resistor R3 and the fourth resistor R4 satisfy R2-R3-2R 4;
the capacitance values of the second capacitor C2, the third capacitor C3 and the fourth capacitor C4 satisfy C2-C3-1/2-C4.
5. The active band-stop filter circuit according to claim 3 or 4, wherein the center frequency of the filter circuit is adjusted by the resistance value of the second resistor R2, the third resistor R3 or the fourth resistor R4, or the capacitance value of the second capacitor C2, the third capacitor C3 or the fourth capacitor C4.
6. The active band-stop filter circuit of claim 3, wherein the attenuation slope of the high-pass filter branch is adjusted by the resistance of the fifth resistor R5.
7. The active band-stop filter circuit of claim 1, wherein the amplifying circuit comprises at least one operational amplifier U1A, a sixth resistor R6, a seventh resistor R7, a second positive power supply + VCC2, and a second reference voltage VREF2, wherein the sixth resistor R6 is connected between the second reference power supply VREF2 and the inverting input terminal of the operational amplifier U1A, the seventh resistor R7 is connected between the inverting input terminal and the output terminal of the operational amplifier, the positive power supply input terminal of the operational amplifier U1A is connected to the second positive power supply + VCC2, and the negative power supply input terminal of the operational amplifier U1A is connected to a negative power supply-VCC or ground.
8. The active band-stop filter circuit of claim 7, wherein the circuit gain is adjusted by the resistances of the sixth resistor R6 and the seventh resistor R7.
9. The active band-stop filter circuit according to claim 7, wherein when the operational amplifier U1A is powered by dual power sources, the negative power input is connected to a negative power source-VCC, and VREF2 is 0; when the operational amplifier U1A is powered by a single power supply, the negative power supply input is grounded, and VREF2 is 1/2VCC 2.
10. The active band-reject filter circuit of any one of claims 2, 3, 7 or 9, wherein the first positive power supply + VCC1 and the second positive power supply + VCC2 are the same positive power supply, and the first reference voltage VREF1 and the second reference voltage VREF2 are the same reference voltage.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420288638.5U CN203912166U (en) | 2014-05-30 | 2014-05-30 | Active band stop filter circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420288638.5U CN203912166U (en) | 2014-05-30 | 2014-05-30 | Active band stop filter circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN203912166U true CN203912166U (en) | 2014-10-29 |
Family
ID=51786407
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201420288638.5U Expired - Lifetime CN203912166U (en) | 2014-05-30 | 2014-05-30 | Active band stop filter circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN203912166U (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104053094A (en) * | 2014-05-30 | 2014-09-17 | 歌尔声学股份有限公司 | Active band-stop filtering circuit |
| CN106658303A (en) * | 2016-12-01 | 2017-05-10 | 北京卓锐微技术有限公司 | Microphone system and amplifying circuit |
| RU2782958C1 (en) * | 2022-03-03 | 2022-11-07 | федеральное государственное бюджетное образовательное учреждение высшего образования "Донской государственный технический университет" (ДГТУ) | Rejector filter of the sallen-key family based on a multi-differential operational amplifier |
-
2014
- 2014-05-30 CN CN201420288638.5U patent/CN203912166U/en not_active Expired - Lifetime
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104053094A (en) * | 2014-05-30 | 2014-09-17 | 歌尔声学股份有限公司 | Active band-stop filtering circuit |
| CN104053094B (en) * | 2014-05-30 | 2018-02-06 | 歌尔股份有限公司 | A kind of active rejector circuit |
| CN106658303A (en) * | 2016-12-01 | 2017-05-10 | 北京卓锐微技术有限公司 | Microphone system and amplifying circuit |
| RU2782958C1 (en) * | 2022-03-03 | 2022-11-07 | федеральное государственное бюджетное образовательное учреждение высшего образования "Донской государственный технический университет" (ДГТУ) | Rejector filter of the sallen-key family based on a multi-differential operational amplifier |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN211321301U (en) | Analog front-end circuit and signal acquisition device | |
| CN102908137B (en) | Single-channel ECG (Electrocardiogram) collection chip | |
| CN104000584A (en) | Weak signal acquisition circuit with high SNR (Signal to Noise Ratio) | |
| CN105048989A (en) | Low pass filter with common-mode noise reduction | |
| CN104333333B (en) | A kind of single-ended amplifier and its noise cancellation method | |
| CN203912166U (en) | Active band stop filter circuit | |
| CN106535022B (en) | A kind of earphone Dolby circuit with power amplifier function with balanced device | |
| CN109962871B (en) | ASK amplitude modulation signal envelope detection system | |
| CN104053094B (en) | A kind of active rejector circuit | |
| CN203027447U (en) | Microphone audio output circuit and microphone | |
| CN103633956A (en) | Charge amplifier | |
| CN207266266U (en) | Analog differential circuit and audio frequency apparatus | |
| EP3298688A1 (en) | An ultra-low-power and low-noise amplifier | |
| CN103997303B (en) | For the high-gain preamplifier and electret microphone of electret microphone | |
| JP6257262B2 (en) | Condenser microphone | |
| CN205610907U (en) | Audio playback system and broadcasting system | |
| CN104482945A (en) | Overvoltage protection and signal conditioning system for sensor | |
| CN101964936B (en) | Processing chip for digital microphone, input circuit thereof and digital microphone | |
| CN103888092B (en) | A kind of differential pickup signal amplifies modulate circuit | |
| CN104639077B (en) | A kind of passive filtering amplifying circuit | |
| CN106533389A (en) | Multi-order filtering circuit | |
| WO2017193345A1 (en) | Audio signal acquisition circuit | |
| CN101834574A (en) | Amplifier circuit and method of signal amplification | |
| CN203563186U (en) | Noise reduction circuit and voice audio driving circuit provided with same | |
| CN109194304B (en) | Band-pass filter suitable for physiological signal processing |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C56 | Change in the name or address of the patentee | ||
| CP01 | Change in the name or title of a patent holder |
Address after: 261031 Dongfang Road, Weifang high tech Industrial Development Zone, Shandong, China, No. 268 Patentee after: Goertek Inc. Address before: 261031 Dongfang Road, Weifang high tech Industrial Development Zone, Shandong, China, No. 268 Patentee before: Goertek Inc. |
|
| TR01 | Transfer of patent right |
Effective date of registration: 20200612 Address after: 266104 room 103, 396 Songling Road, Laoshan District, Qingdao, Shandong Province Patentee after: Goer Microelectronics Co.,Ltd. Address before: 261031 Dongfang Road, Weifang high tech Industrial Development Zone, Shandong, China, No. 268 Patentee before: GOERTEK Inc. |
|
| TR01 | Transfer of patent right | ||
| CX01 | Expiry of patent term |
Granted publication date: 20141029 |
|
| CX01 | Expiry of patent term |