CN204216856U - A kind of automatic gain control circuit being applied to ultrasonic calorimeter - Google Patents
A kind of automatic gain control circuit being applied to ultrasonic calorimeter Download PDFInfo
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- CN204216856U CN204216856U CN201420691024.1U CN201420691024U CN204216856U CN 204216856 U CN204216856 U CN 204216856U CN 201420691024 U CN201420691024 U CN 201420691024U CN 204216856 U CN204216856 U CN 204216856U
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Abstract
The utility model relates to a kind of automatic gain control circuit being applied to ultrasonic calorimeter, comprise control voltage and form circuit, gain controlled amplifying circuit, gain controlled amplifying circuit ultrasonic wave output signal Vo is formed circuit, voltage follow and gain controlled amplifying circuit formed loop by the comparison circuit in control voltage formation circuit, the average detection of area, direct voltage successively, and reference voltage, rectifying and wave-filtering form circuit with comparison circuit and direct voltage respectively and be connected.Beneficial effect is: can control the intensity outputed signal, avoid sampled signal distortion, output signal more accurate.
Description
Technical field
The utility model relates to the automatic gain control circuit of control or instrument and meter automatically, particularly relates to a kind of automatic gain control circuit being applied to ultrasonic calorimeter.
Background technology
The dynamic amplitude scope of ultrasonic echo signal is very wide, and along with the rising of tested flow velocity, the echo signal amplitude received changes from tens mV to hundreds of mV, and its amplitude alters a great deal.Some instrument and meters, in signal processing, do not use gain control circuit, just directly carry out detection and calculating.When echo-signal amplitude is very little, detecting circuit cannot detect, causes single-chip microcomputer finally to can not get Received signal strength, finally causes instrument measurement failure; When echo-signal amplitude is larger, single-chip microcomputer obtains saturated Received signal strength, causes distorted signals, finally causes instrument measurement precision to exceed requirement.Also have some instrument only to use open loop gain circuit, when echo signal intensity is low, detecting circuit perhaps can detect the signal after amplification, and single-chip microcomputer perhaps can normally be measured, but effectively cannot ensure certainty of measurement; When echo signal intensity height, after open loop gain circuit amplifies, cause signal saturated, detecting circuit detects the echo-signal of distortion, finally causes the distorted signals that single-chip microcomputer receives, and greatly reduces the precision of instrument output signal; If echo-signal amplitude is too high, circuit can be made after open-loop gain to produce self-excitation, thus make detecting circuit signal be detected, cause single chip computer measurement failure.The defect more than designed mainly is:
If 1 instrument adopts open loop gain circuit, when echo signal intensity height, after amplifying through open-loop gain, cause echo-signal saturated, detection telecommunications exports distortion; Or make circuit produce self-excitation, cannot echo-signal be detected, greatly reduce the precision of instrument output signal.
If do not use automatic gain control circuit in 2 instrument, single-chip microcomputer can be caused finally to can not get Received signal strength, or obtain saturated Received signal strength, cause and measure unsuccessfully.
Summary of the invention
In view of prior art exist deficiency, the utility model provides a kind of intensity that can improve signal, avoids sampled signal distortion, control after output signal a kind of automatic gain control circuit being applied to ultrasonic calorimeter more accurately.
The utility model to achieve these goals, the technical scheme adopted is: a kind of circuit being applied to the automatic growth control of ultrasonic calorimeter, it is characterized in that: one end of input signal Vi and resistance R1, reverse input end 8 pin of the amplifier U1 with gain connects, the other end of resistance R1, input in the same way 1 pin of the amplifier U1 with gain, 2 pin are connected to ground, gain control end 3 pin of the amplifier U1 with gain is connected to reverse input end 6 pin and output 7 pin of two-way operational amplifier U2B passage two, end in the same way 5 pin of U2B passage two is connected to resistance R2, resistance R3, one end of resistance R4 and electric capacity C2, the other end of resistance R2 connects one end and the negative supply of electric capacity C1, resistance R3, electric capacity C1, the other end ground connection of electric capacity C2, the other end of resistance R4 connects the negative pole of diode D1, output 1 pin of two-way operational amplifier U2A passage one is connected to the positive pole of diode D1 and one end of electric capacity C5, the other end of electric capacity C5 is connected to input in the same way 3 pin of U2A passage one, reverse input end 2 pin of U2A passage one is connected to one end of resistance R6 by resistance R5, the positive pole of diode D2, the minus earth of diode D2, the other end of resistance R6 is connected to positive supply, 6 pin of the amplifier U1 with gain, 8 pin of two-way operational amplifier U2A, one end of electric capacity C3 is connected to positive supply, 7 pin of U1, 4 pin of U2A, one end of electric capacity C4 is connected to negative supply, electric capacity C3, the other end of electric capacity C4 is connected to ground, output 5 pin of the amplifier U1 with gain, the input in the same way 3 pin output signal Vo of two-way operational amplifier U2A passage one.
The beneficial effects of the utility model are: can control the intensity outputed signal, avoid sampled signal distortion, make output signal more accurate.Due to the use of above-mentioned control method, the amplitude and sample signal strength that make the Received signal strength Vo of ultrasonic calorimeter are had nothing to do.When sampled signal is weak, can realizes automatically strengthening signal strength signal intensity by automatic growth control, can not sampled data be lost, ensure that the quantity that instrument is sampled; When sampled signal is strong, automatically can controls to reduce gain factor, avoid distorted signals, ensure that the quality that instrument is sampled.Therefore, follow-up detecting circuit can extract the time of reception accurately easily from Received signal strength, thus ensures the precision that single-chip microcomputer calculates, and improves the measurement accuracy of instrument.
Accompanying drawing explanation
Fig. 1 is that circuit of the present utility model connects block diagram;
Fig. 2 is circuit theory diagrams of the present utility model.
Embodiment
As Fig. 1, shown in Fig. 2, a kind of circuit being applied to the automatic growth control of ultrasonic calorimeter, one end of input signal Vi and resistance R1, reverse input end 8 pin of the amplifier U1 with gain connects, the other end of resistance R1, input in the same way 1 pin of the amplifier U1 with gain, 2 pin are connected to ground, and gain control end 3 pin of the amplifier U1 of band gain is connected to reverse input end 6 pin and output 7 pin of two-way operational amplifier U2B passage two, and end in the same way 5 pin of U2B passage two is connected to resistance R2, resistance R3, one end of resistance R4 and electric capacity C2, the other end of resistance R2 connects one end and the negative supply of electric capacity C1, resistance R3, electric capacity C1, the other end ground connection of electric capacity C2, the other end of resistance R4 connects the negative pole of diode D1, output 1 pin of two-way operational amplifier U2A passage one is connected to the positive pole of diode D1 and one end of electric capacity C5, the other end of electric capacity C5 is connected to input in the same way 3 pin of U2A passage one, and reverse input end 2 pin of U2A passage one is connected to one end of resistance R6 by resistance R5, the positive pole of diode D2, the minus earth of diode D2, the other end of resistance R6 is connected to positive supply, 6 pin of the amplifier U1 of band gain, 8 pin of two-way operational amplifier U2A, one end of electric capacity C3 is connected to positive supply, 7 pin of U1, 4 pin of U2A, one end of electric capacity C4 is connected to negative supply, electric capacity C3, the other end of electric capacity C4 is connected to ground, output 5 pin of the amplifier U1 of band gain, the input in the same way 3 pin output signal Vo of two-way operational amplifier U2A passage one.
Amplifier U1 with gain is VCA810; Two-way operational amplifier U2A, two-way operational amplifier U2B are OP37.
A kind of circuit control method being applied to the automatic growth control of ultrasonic calorimeter: so-called automatic growth control refers to the control method adjusted with signal strength signal intensity of amplifying circuit Gain Automaticly.The circuit realizing this function is called for short agc circuit.Agc circuit is a close loop electronic circuit, is also a degeneration factor, and it can be divided into gain controlled amplifying circuit and control voltage forms circuit two parts.Gain controlled amplifying circuit is positioned at forward and amplifies path, and its gain changes with control voltage.Control voltage forms circuit and belongs to a kind of negative-feedback circuit, and its basic element of character is AGC wave detector and low pass filter.The output signal of amplifying circuit is through detection and after rectifying and wave-filtering, produce the direct voltage in order to ride gain controlled amplifier.When input signal increases, output signal and gain control direct voltage and also increase thereupon.Gain-controlled voltage increases, and the gain of amplifying circuit is declined, and the amplitude finally making it output signal does not change with the change of input signal substantially, reaches the object of automatic growth control.
AGC has two kinds of control modes: a kind of is utilize the mode increasing AGC control voltage to reduce the mode of gain forward AGC, and a kind of is utilize the mode reducing AGC control voltage to reduce the mode of gain reverse AGC.Forward AGC control ability is strong, and required control power is large, and controlled amplifying stage working point mobility scale is large, and amplifier two ends impedance variation is also large; Reverse AGC required control power is little, and control range is also little.This circuit design have selected forward AGC control mode.
Operation principle:
8 pin that echo-signal carries the inverting input of the amplifier U1 of gain enter, and from 5 pin output ultrasonic wave signal Vo, two-way operational amplifier U2A is by Vo and DC reference voltage V
rcompare, be therefore only greater than V at the positive peak of Vo
rtime, two-way operational amplifier U2A just has positive pulse to export, and compares V
rlarger, the width of two-way operational amplifier U2A positive pulse output signal is wider.This positive pulse exports is carried out the detection of area average by diode D1 and electric capacity C2, and the half peak value size causing the direct voltage on electric capacity C2 and Vo is functional relation.In figure, resistance R4 is the positive charge resistance of electric capacity C2, and diode D1 ensures that electric capacity C2 does not discharge to two-way operational amplifier U2A.In addition, resistance R3 is the discharge resistance of electric capacity C2, ensures that electric capacity C2 has suitable pressure decay rate.And resistance R2 and resistance R3 can provide quiescent value for the voltage Vc ' on electric capacity C2, this value is by gain time static for formation VCA810.Two-way operational amplifier U2B is a simple voltage follower, and the voltage Vc ' on electric capacity C2 is delivered to gain control input 3 pin of U1 by it in the ratio of 1:1, become direct-current control voltage Vc.
Larger ultrasonic output signal Vo is detected as a direct voltage Vc ', and Vo is larger, and then Vc ' is larger, and the gain of VCA810 will be less; Otherwise ultrasonic signal Vo is less, the gain of VCA810 will increase automatically.Visible, when the amplitude of echo-signal Vi changes, because above-mentioned forward AGC controls, output signal Vo amplitude can be kept substantially constant.Experiment proves, in effective input range, the changes in amplitude of input signal 100 times, the change of Vo output amplitude is maximum is only 10%.
Claims (1)
1. one kind is applied to the automatic gain control circuit of ultrasonic calorimeter, it is characterized in that: one end of input signal Vi and resistance R1, reverse input end 8 pin of the amplifier U1 with gain connects, the other end of resistance R1, input in the same way 1 pin of the amplifier U1 with gain, 2 pin are connected to ground, gain control end 3 pin of the amplifier U1 with gain is connected to reverse input end 6 pin and output 7 pin of two-way operational amplifier U2B passage two, end in the same way 5 pin of U2B passage two is connected to resistance R2, resistance R3, one end of resistance R4 and electric capacity C2, the other end of resistance R2 connects one end and the negative supply of electric capacity C1, resistance R3, electric capacity C1, the other end ground connection of electric capacity C2, the other end of resistance R4 connects the negative pole of diode D1, output 1 pin of two-way operational amplifier U2A passage one is connected to the positive pole of diode D1 and one end of electric capacity C5, the other end of electric capacity C5 is connected to input in the same way 3 pin of U2A passage one, reverse input end 2 pin of U2A passage one is connected to one end of resistance R6 by resistance R5, the positive pole of diode D2, the minus earth of diode D2, the other end of resistance R6 is connected to positive supply, 6 pin of the amplifier U1 with gain, 8 pin of two-way operational amplifier U2A, one end of electric capacity C3 is connected to positive supply, 7 pin of U1, 4 pin of U2A, one end of electric capacity C4 is connected to negative supply, electric capacity C3, the other end of electric capacity C4 is connected to ground, output 5 pin of the amplifier U1 with gain, the input in the same way 3 pin output signal Vo of two-way operational amplifier U2A passage one.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420691024.1U CN204216856U (en) | 2014-11-18 | 2014-11-18 | A kind of automatic gain control circuit being applied to ultrasonic calorimeter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420691024.1U CN204216856U (en) | 2014-11-18 | 2014-11-18 | A kind of automatic gain control circuit being applied to ultrasonic calorimeter |
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| Publication Number | Publication Date |
|---|---|
| CN204216856U true CN204216856U (en) | 2015-03-18 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201420691024.1U Withdrawn - After Issue CN204216856U (en) | 2014-11-18 | 2014-11-18 | A kind of automatic gain control circuit being applied to ultrasonic calorimeter |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104393851A (en) * | 2014-11-18 | 2015-03-04 | 中环天仪股份有限公司 | Automatic gain control circuit applied to ultrasonic heat meter and control method of automatic gain control circuit |
| CN109962687A (en) * | 2019-05-06 | 2019-07-02 | 成都师范学院 | Amplifying circuit is controlled from dynamic transconductance |
-
2014
- 2014-11-18 CN CN201420691024.1U patent/CN204216856U/en not_active Withdrawn - After Issue
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104393851A (en) * | 2014-11-18 | 2015-03-04 | 中环天仪股份有限公司 | Automatic gain control circuit applied to ultrasonic heat meter and control method of automatic gain control circuit |
| CN104393851B (en) * | 2014-11-18 | 2017-05-17 | 中环天仪股份有限公司 | Automatic gain control circuit applied to ultrasonic heat meter |
| CN109962687A (en) * | 2019-05-06 | 2019-07-02 | 成都师范学院 | Amplifying circuit is controlled from dynamic transconductance |
| CN109962687B (en) * | 2019-05-06 | 2023-11-10 | 成都师范学院 | Automatic transconductance control amplifying circuit |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| AV01 | Patent right actively abandoned | ||
| AV01 | Patent right actively abandoned |
Granted publication date: 20150318 Effective date of abandoning: 20170517 |