CN113470491A - Automatic gain control circuit for experiment teaching - Google Patents
Automatic gain control circuit for experiment teaching Download PDFInfo
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- CN113470491A CN113470491A CN202110823342.3A CN202110823342A CN113470491A CN 113470491 A CN113470491 A CN 113470491A CN 202110823342 A CN202110823342 A CN 202110823342A CN 113470491 A CN113470491 A CN 113470491A
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- 238000002474 experimental method Methods 0.000 title claims description 18
- 238000006243 chemical reaction Methods 0.000 claims abstract description 21
- 238000004458 analytical method Methods 0.000 claims description 43
- 239000003990 capacitor Substances 0.000 claims description 9
- 238000011160 research Methods 0.000 abstract description 4
- 238000004088 simulation Methods 0.000 abstract description 4
- 230000000007 visual effect Effects 0.000 abstract description 2
- 238000000034 method Methods 0.000 description 5
- 230000005669 field effect Effects 0.000 description 4
- 239000008186 active pharmaceutical agent Substances 0.000 description 3
- 230000003321 amplification Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000003199 nucleic acid amplification method Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000003139 buffering effect Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000012549 training Methods 0.000 description 1
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- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09B—EDUCATIONAL OR DEMONSTRATION APPLIANCES; APPLIANCES FOR TEACHING, OR COMMUNICATING WITH, THE BLIND, DEAF OR MUTE; MODELS; PLANETARIA; GLOBES; MAPS; DIAGRAMS
- G09B23/00—Models for scientific, medical, or mathematical purposes, e.g. full-sized devices for demonstration purposes
- G09B23/06—Models for scientific, medical, or mathematical purposes, e.g. full-sized devices for demonstration purposes for physics
- G09B23/18—Models for scientific, medical, or mathematical purposes, e.g. full-sized devices for demonstration purposes for physics for electricity or magnetism
- G09B23/183—Models for scientific, medical, or mathematical purposes, e.g. full-sized devices for demonstration purposes for physics for electricity or magnetism for circuits
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03G—CONTROL OF AMPLIFICATION
- H03G3/00—Gain control in amplifiers or frequency changers
- H03G3/20—Automatic control
- H03G3/30—Automatic control in amplifiers having semiconductor devices
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- Educational Technology (AREA)
- Theoretical Computer Science (AREA)
- Control Of Amplification And Gain Control (AREA)
Abstract
The invention discloses an automatic gain control circuit for experimental teaching, which comprises a first operational amplifier, a resistive device, a signal input end, a signal output end and a conversion control circuit, wherein the resistive device is electrically connected between the other input end of the first operational amplifier and the output end of the conversion control circuit; the resistance of the resistive device can change according to the output voltage of the conversion control circuit, and the conversion control circuit is used for converting the alternating current signal output by the first operational amplifier into a direct current signal and loading the direct current signal on the resistive device; through the automatic gain control circuit, each device needs manual connection of a student (non-simulation device), so that the practical exercise capacity of the student can be effectively exercised, and after the circuit is built, the affected variable of signal output is only related to the input signal, so that the automatic gain control circuit is convenient for the student to analyze and research, and has the advantages of simple and visual parameter adjustment, small output dynamic range and high precision.
Description
Technical Field
The invention relates to the technical field of experimental teaching circuit design, in particular to an automatic gain control circuit for experimental teaching.
Background
At present, simulation electronic technology experiment teaching content is relatively traditional, and in order to be attached to the innovative talent training teaching concept of train promotion, it is especially important to properly introduce some knowledge points of an electronic race into the analog electronic experiment teaching. The automatic gain control is used as a high-frequency examination point of an electronic match, and the introduction of the analog-to-digital experiment teaching is necessary. The automatic gain control circuit can be roughly divided into the following structures: feed-forward, feedback, and hybrid. Wherein the feedforward type circuit is unstable, and the experimental phenomenon is not easy to capture; the hybrid circuit is relatively complex, large in power consumption and relatively difficult to debug, so that the feedback type automatic gain control circuit is adopted, and the hybrid circuit is relatively suitable for routine experiment teaching. The automatic gain control circuit is used for realizing amplification gain control on a detection object with large signal amplitude variation, at present, for some feedback automatic gain experiment projects, the adopted circuit is relatively complex, the wiring real operation is relatively difficult, simulation is generally used for carrying out experiments, the circuit performance is relatively low, the affected variables are more, understanding is difficult for some students, and the measurement parameters are relatively single, so that the practical capability of the students cannot be improved.
Disclosure of Invention
The invention aims to solve the technical problems and provide an automatic gain control circuit for experimental teaching, which can effectively exercise the dynamic performance of students, has simple and visual parameter adjustment and small output dynamic range and is easy to understand.
In order to achieve the above object, the present invention discloses an automatic gain control circuit for experiment teaching, which includes a first operational amplifier, a resistive device, a signal input end, a signal output end and a conversion control circuit, wherein the signal input end is electrically connected to one input end of the first operational amplifier, the signal output end is electrically connected to an output end of the first operational amplifier, the resistive device is electrically connected between the other input end of the first operational amplifier and the output end of the conversion control circuit, and the input end of the conversion control circuit is electrically connected to the output end of the first operational amplifier; the resistance of the resistive device can change according to the output voltage of the conversion control circuit, the conversion control circuit is used for converting the alternating current signal output by the first operational amplifier into a direct current signal to be loaded on the resistive device, the resistive device is a transistor, and the transistor works in a variable resistance area.
Preferably, the transistor comprises a field effect transistor.
Preferably, the signal input terminal is electrically connected to the non-inverting input terminal of the first operational amplifier.
Preferably, the conversion control circuit includes a second operational amplifier electrically connected to the output terminal of the first operational amplifier, the output terminal of the second operational amplifier is electrically connected to a first rectifying diode, and the output terminal of the first operational amplifier is electrically connected to the output terminal of the second operational amplifier through a second rectifying diode.
Preferably, the conversion control circuit further includes a third operational amplifier electrically connected to the output terminal of the second operational amplifier, the output terminal of the third operational amplifier is electrically connected to the resistive device, the output terminal of the first operational amplifier is electrically connected to the inverting input terminal of the second operational amplifier, and the output terminal of the second operational amplifier is electrically connected to the inverting input terminal of the third operational amplifier.
Preferably, the output end of the second operational amplifier and/or the output end of the third operational amplifier is provided with a filter capacitor.
Preferably, further comprising signal analysis acquisition points comprising one or more of a first signal analysis acquisition point, a second signal analysis acquisition point, a third signal analysis acquisition point, a fourth signal analysis acquisition point, a fifth signal analysis acquisition point, and a sixth signal analysis acquisition point;
the first signal analysis acquisition point is arranged at the input end of the first operational amplifier;
the second signal analysis acquisition point is arranged at the output end of the first operational amplifier;
the third signal analysis acquisition point is arranged at the output end of the second operational amplifier;
the fourth signal analysis acquisition point is arranged at the positive end of a filter capacitor between the second operational amplifier and the third operational amplifier;
the fifth signal analysis acquisition point is arranged at the output end of the third operational amplifier;
the sixth signal analysis acquisition point is arranged at the positive end of the filter capacitor between the third operational amplifier and the resistive device.
Compared with the prior art, the automatic gain control circuit for experiment teaching has the beneficial technical effects that:
1. the control circuit for the automatic dispute feedback of the analog signals is formed by the first operational amplifier, the resistive device with the resistance value automatically changing according to the loaded voltage and the conversion control circuit, and in the experimental process, each device needs to be manually connected by students (non-simulation devices), so that the real-time operation capability of the students can be effectively exercised;
2. in the experimental process, after the circuit is built, the affected variable of the signal output is only related to the input signal, so that the analysis and research of students are facilitated, the parameter adjustment is simple and intuitive, the output dynamic range is small, and the precision is high.
Drawings
Fig. 1 is a schematic circuit diagram of an automatic gain control circuit according to an embodiment of the present invention.
Detailed Description
In order to explain technical contents, structural features, and objects and effects of the present invention in detail, the following detailed description is given with reference to the accompanying drawings in conjunction with the embodiments.
Referring to fig. 1, this embodiment discloses an automatic gain control circuit for experiment teaching to train the practical ability and deepen the pair of studentsUnderstanding of automatic gain control circuits. Specifically, the automatic gain control circuit comprises a first operational amplifier A1Resistive device T and signal input end UiAnd a signal output end UoAnd a switching control circuit 100. Signal input terminal UiFor collecting analog signals for experiment, and a first operational amplifier A1One of the input terminals is electrically connected. Signal output terminal UoFor outputting the amplified signal, and a first operational amplifier A1The output ends of the two ends are electrically connected. The resistive device T is electrically connected to the first operational amplifier A1Between the other input terminal of the first operational amplifier a and the output terminal of the switching control circuit 1001Providing a feedback resistor, converting the input terminal of the control circuit 100 and the first operational amplifier A1The output ends of the two ends are electrically connected. The resistance of the resistive device T may vary according to the output voltage of the switching control circuit 100, the switching control circuit 100 being adapted to couple the first operational amplifier a1The output alternating current signal is converted into a direct current signal and loaded on the resistive device T. Preferably, the signal input terminal in the present embodiment is electrically connected to the first operational amplifier a1Serving as a non-inverting amplifier.
The working principle of the automatic gain control circuit in the above embodiment is as follows: the input signal passes through a parallel resistor R1、R2From the first operational amplifier A1Is fed through a first operational amplifier A1After the amplification process, the signal enters the conversion control circuit 100, and the conversion control circuit 100 converts the first operational amplifier A1The output alternating current signal is converted into a direct current signal, and the direct current signal is loaded on the resistive device T, so that the resistance of the resistive device T is correspondingly changed, and the resistive device T is the first operational amplifier A1The feedback resistance is provided so that a change in the resistance of the resistive device T directly affects the first operational amplifier a1So that the first operational amplifier a1The output signal of the output terminal is stably controlled. Therefore, the automatic gain control circuit disclosed by the embodiment is completely built by adopting the entity circuit element, and is used for student experimentsAnd all the components need to be connected by hands in person, so that the practical operation and hand-operating capacity of students can be effectively exercised. In addition, after the circuit is built, the affected variable of the signal output is only related to the input signal, so that the analysis and research of students are facilitated, and when experimental parameters need to be adjusted, the models of the used corresponding components are only needed to be changed.
Further, the resistive device T is a transistor, and the transistor operates in the variable resistance region. Specifically, the transistor in this embodiment is preferably a field effect transistor, and the drain-source resistance R of the field effect transistorDSAnd is a first operational amplifier A1Configured constant-resistance auxiliary feedback resistor R3、R4Together forming a first operational amplifier A1When the first operational amplifier A is used as the feedback network of1When used as a non-inverting amplifier, its voltage gain AuThe following formula is satisfied,
according to the formula, the drain-source resistance R of the field effect transistorDSWhen changed, the first operational amplifier A1Will change in voltage gain and drain-source resistance RDSBy a voltage U applied to the fet gate by the switching control circuit 100GIs determined so that the first operational amplifier A1Is fed back to the input terminal, affecting the first operational amplifier a1Real-time operating conditions.
Further, the conversion control circuit 100 includes a first operational amplifier A1The output end of the first operational amplifier A is electrically connected with the output end of the second operational amplifier A2A second operational amplifier A2The output end of the first rectifier diode D is electrically connected with the output end of the second rectifier diode D1A first operational amplifier A1Is passed through a second rectifying diode D2And a second operational amplifier A2Is transported byThe output end is electrically connected. In this embodiment, a second operational amplifier A is used2Is connected to a first operational amplifier A1The output end of the voltage follower is mainly used as a voltage follower, and plays roles of buffering and isolating so as to improve the safety performance of the circuit. From a first operational amplifier A1The output signals are ac signals (sine waves) which are respectively passed through the first rectifier diodes D1And a second rectifying diode D2In the second operational amplifier A2The output terminal of the first operational amplifier A is obtained1The output full-wave rectified DC signal. In addition, a second operational amplifier A2Is provided with a feedback resistor R5、R6And a ground resistance R7。
Preferably, for convenient wiring, the second operational amplifier A2And the first operational amplifier A1Is electrically connected, so that the first rectifying diode D1And a second rectifying diode D2Are connected in the same direction, a first operational amplifier A1The positive part of the output AC signal passes through a second rectifier diode D2Rectified output, first operational amplifier A1The negative part of the output AC signal passes through a second operational amplifier A2After phase inversion, the signal becomes a positive signal and then passes through a first rectifier diode D1And (6) rectifying the output. In this embodiment, the second operational amplifier A2Has an inverting function, so that the conversion control circuit 100 further includes a second operational amplifier A2The output end of the third operational amplifier A is electrically connected with3A third operational amplifier A3Is connected to the output terminal of the power supply and passes through a series resistor R8、R13A second operational amplifier A electrically connected with the resistive device T2And the output terminal of the third operational amplifier A3The inverting input terminal of the circuit is electrically connected. Through a third operational amplifier A3Is provided with a second operational amplifier A2The inverted signal is inverted again and becomes loaded on the resistive device T in the same direction as the input signal. In this embodiment, a third operational amplifier A is also provided3Is provided with a feedback resistor R10、R11And a ground resistance R12。
In addition, in order to improve the working stability of the circuit and facilitate accurate adjustment of students, a second operational amplifier A2And/or the third operational amplifier A3The output end of the filter is provided with a filter capacitor C1、C2。
Furthermore, in order to facilitate students to know the characteristics of the signals at each stage in the experimental process, the automatic gain control circuit in the embodiment further comprises a signal analysis and acquisition point. The signal analysis acquisition points comprise one or more of a first signal analysis acquisition point A, a second signal analysis acquisition point B, a third signal analysis acquisition point C, a fourth signal analysis acquisition point D, a fifth signal analysis acquisition point E and a sixth signal analysis acquisition point F;
the first signal analysis acquisition point A is arranged on the first operational amplifier A1An input terminal of (1);
the second signal analysis acquisition point B is arranged on the first operational amplifier A1An output terminal of (a);
the third signal analysis acquisition point C is arranged on the second operational amplifier A2An output terminal of (a);
a fourth signal analysis acquisition point D is arranged on the second operational amplifier A2And a third operational amplifier A3Filter capacitor C therebetween2The positive terminal of (1);
a fifth signal analysis acquisition point E is arranged on the third operational amplifier A3An output terminal of (a);
a sixth signal analysis acquisition point F is arranged on the third operational amplifier A3A filter capacitor C between the resistive device T and the filter1The positive terminal of (1).
Through the setting of a plurality of signal analysis collection points, in the experimentation, the student can gather experimental data from each part of circuit according to the demand to there is a clear understanding to the processing procedure of automatic gain control circuit to the signal, and the parameter research is comparatively various, lets the theory of operation that the student can observe the experiment directly perceivedly.
The above disclosure is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the scope of the present invention, therefore, the present invention is not limited by the appended claims.
Claims (8)
1. An automatic gain control circuit for experiment teaching is characterized by comprising a first operational amplifier, a resistive device, a signal input end, a signal output end and a conversion control circuit, wherein the signal input end is electrically connected with one input end of the first operational amplifier, the signal output end is electrically connected with the output end of the first operational amplifier, the resistive device is electrically connected between the other input end of the first operational amplifier and the output end of the conversion control circuit, and the input end of the conversion control circuit is electrically connected with the output end of the first operational amplifier; the resistance of the resistive device can change according to the output voltage of the conversion control circuit, and the conversion control circuit is used for converting the alternating current signal output by the first operational amplifier into a direct current signal and loading the direct current signal on the resistive device.
2. The agc circuit of claim 1, wherein the resistive device is a transistor, the transistor operating in a variable resistance region.
3. The agc circuit of claim 2, wherein the transistor comprises a fet.
4. The agc circuit of claim 1, wherein the signal input is electrically connected to a non-inverting input of the first op amp.
5. The automatic gain control circuit for teaching experiments according to claim 4, wherein said switching control circuit comprises a second operational amplifier electrically connected to the output terminal of said first operational amplifier, the output terminal of said second operational amplifier is electrically connected to a first rectifying diode, and the output terminal of said first operational amplifier is electrically connected to the output terminal of said second operational amplifier through a second rectifying diode.
6. The automatic gain control circuit for teaching experiments according to claim 5, wherein said switching control circuit further comprises a third operational amplifier electrically connected to an output of said second operational amplifier, an output of said third operational amplifier being electrically connected to said resistive device, an output of said first operational amplifier being electrically connected to an inverting input of said second operational amplifier, an output of said second operational amplifier being electrically connected to an inverting input of said third operational amplifier.
7. The automatic gain control circuit for teaching experiments according to claim 6, wherein the output terminal of the second operational amplifier and/or the output terminal of the third operational amplifier is provided with a filter capacitor.
8. The automatic gain control circuitry for teaching experiments according to claim 7 further comprising signal analysis acquisition points including one or more of a first signal analysis acquisition point, a second signal analysis acquisition point, a third signal analysis acquisition point, a fourth signal analysis acquisition point, a fifth signal analysis acquisition point and a sixth signal analysis acquisition point;
the first signal analysis acquisition point is arranged at the input end of the first operational amplifier;
the second signal analysis acquisition point is arranged at the output end of the first operational amplifier;
the third signal analysis acquisition point is arranged at the output end of the second operational amplifier;
the fourth signal analysis acquisition point is arranged at the positive end of a filter capacitor between the second operational amplifier and the third operational amplifier;
the fifth signal analysis acquisition point is arranged at the output end of the third operational amplifier;
the sixth signal analysis acquisition point is arranged at the positive end of the filter capacitor between the third operational amplifier and the resistive device.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202110823342.3A CN113470491A (en) | 2021-07-20 | 2021-07-20 | Automatic gain control circuit for experiment teaching |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202110823342.3A CN113470491A (en) | 2021-07-20 | 2021-07-20 | Automatic gain control circuit for experiment teaching |
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| CN113470491A true CN113470491A (en) | 2021-10-01 |
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Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1987006751A1 (en) * | 1986-04-29 | 1987-11-05 | Amalgamated Wireless (Australasia) Limited | Audio-tactile pedestrian push button signalling system |
| CN87103070A (en) * | 1987-04-29 | 1988-11-09 | 北京工业大学 | The automatic gain control circuit of digital communication machine |
| CN2222390Y (en) * | 1995-04-03 | 1996-03-13 | 纪春乡 | Magnetic tape recorder for learning with sentence pause function |
| CN101557204A (en) * | 2009-05-22 | 2009-10-14 | 天津大学 | Automatic gain control circuit of multistage high dynamic range used in ultrasonic distance measurement |
| CN102201792A (en) * | 2010-03-25 | 2011-09-28 | 上海沙丘微电子有限公司 | Automatic gain control circuit of audio power amplifier |
| CN205847205U (en) * | 2016-07-18 | 2016-12-28 | 华南理工大学 | A kind of automatic gain control circuit based on photoconductive resistance |
| CN106936423A (en) * | 2015-12-29 | 2017-07-07 | 柳州桂通科技股份有限公司 | Operational amplifier, driving interface, measuring and controlling equipment, drive circuit and driver |
| CN212675034U (en) * | 2020-06-23 | 2021-03-09 | 歌尔科技有限公司 | Multichannel resistance measuring device |
-
2021
- 2021-07-20 CN CN202110823342.3A patent/CN113470491A/en active Pending
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1987006751A1 (en) * | 1986-04-29 | 1987-11-05 | Amalgamated Wireless (Australasia) Limited | Audio-tactile pedestrian push button signalling system |
| CN87103070A (en) * | 1987-04-29 | 1988-11-09 | 北京工业大学 | The automatic gain control circuit of digital communication machine |
| CN2222390Y (en) * | 1995-04-03 | 1996-03-13 | 纪春乡 | Magnetic tape recorder for learning with sentence pause function |
| CN101557204A (en) * | 2009-05-22 | 2009-10-14 | 天津大学 | Automatic gain control circuit of multistage high dynamic range used in ultrasonic distance measurement |
| CN102201792A (en) * | 2010-03-25 | 2011-09-28 | 上海沙丘微电子有限公司 | Automatic gain control circuit of audio power amplifier |
| CN106936423A (en) * | 2015-12-29 | 2017-07-07 | 柳州桂通科技股份有限公司 | Operational amplifier, driving interface, measuring and controlling equipment, drive circuit and driver |
| CN205847205U (en) * | 2016-07-18 | 2016-12-28 | 华南理工大学 | A kind of automatic gain control circuit based on photoconductive resistance |
| CN212675034U (en) * | 2020-06-23 | 2021-03-09 | 歌尔科技有限公司 | Multichannel resistance measuring device |
Non-Patent Citations (2)
| Title |
|---|
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