CN103905007A - Current input type pre-amplifier - Google Patents
Current input type pre-amplifier Download PDFInfo
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- CN103905007A CN103905007A CN201410153577.6A CN201410153577A CN103905007A CN 103905007 A CN103905007 A CN 103905007A CN 201410153577 A CN201410153577 A CN 201410153577A CN 103905007 A CN103905007 A CN 103905007A
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- operational amplifier
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Abstract
The invention discloses a current input type pre-amplifier. The pre-amplifier comprises an operational amplifier, a feedback resistor RF, an adjustable resistor RP, a diode D1, a diode D2 and a feedback capacitor CF. The inverted input end of the operational amplifier is connected with the positive electrode of the diode D1, the negative electrode of the diode D2, one end of the feedback capacitor CF, one end of the feedback resistor RF and a positive signal source, the negative electrode of the diode D1 and the positive electrode of the diode D2 are grounded, the other end of the feedback resistor RF is connected with the other end of the feedback capacitor CF and the output end of the operational amplifier, the positive phase input end of the operational amplifier is grounded, the adjustable resistor RP is connected between two zero setting ends of the operational amplifier, and a movable contact spring of the adjustable resistor RP is connected with the positive power source end of the operational amplifier. By using the characteristics that the operational amplifier is very large in input impedance, very small in output impedance and extremely large in open loop amplification factor, stable voltage signals can be provided for a post-amplifier without occurrence of errors, and the signals processed by the amplifier are stable and reliable.
Description
Technical field
The present invention relates to a kind of preamplifier, specifically, relate to the imported preamplifier of a kind of electric current, belong to electronic technology field.
Background technology
Measure and control the variation that conventionally needs transducer to carry out some physical quantitys of perception, some transducer transfers current signal output to this variation.And processing of circuit voltage signal is more convenient and reliable, carry out again subsequent treatment so first this current signal is transferred to voltage signal with regard to needs.
General simple conversion is while utilizing current flowing resistance, obtains voltage signal, then process through amplifier at the two ends of resistance.Because the existence of resistance, this resistance can be regarded the internal resistance of signal source as, in the time that rear class amplifying circuit is processed this voltage signal, will produce error, so be difficult to obtain reliable and stable signal.
Summary of the invention
The problem to be solved in the present invention is for above deficiency, and a kind of imported preamplifier of electric current of stable output signal is provided.
For overcoming the above problems, the technical solution adopted in the present invention is: the imported preamplifier of a kind of electric current, is characterized in that: the imported preamplifier of described electric current comprises operational amplifier, feedback resistance RF, adjustable resistance RP, diode D1, diode D2 and feedback capacity CF;
The positive pole of the anti-phase input termination diode D1 of operational amplifier, the negative pole of diode D2, one end and the positive signal source of feedback capacity CF, feedback resistance RF, the negative pole of diode D1, the plus earth of diode D2, the other end of another termination feedback capacity CF of feedback resistance RF and the output of operational amplifier, the positive input end grounding of operational amplifier, between two zeroing ends of operational amplifier, connect adjustable resistance RP
The movable contact spring of adjustable resistance RP connects the positive power source terminal of operational amplifier.
A kind of prioritization scheme, the imported preamplifier of described electric current also comprises resistance R 1, the inverting input of a termination operational amplifier of resistance R 1, one end and the positive signal source of another termination feedback capacity CF of resistance R 1.
Further, the imported preamplifier of described electric current also comprises resistance R 2, resistance R 3, voltage stabilizing two utmost points
Pipe ZD1 and voltage stabilizing didoe ZD2;
The negative pole of voltage stabilizing didoe ZD1, the positive pole of voltage stabilizing didoe ZD2 connect negative signal source ground connection, and the positive pole of voltage stabilizing didoe ZD1 connects negative supply and through connect-15V of resistance R 2, and the negative pole of voltage stabilizing didoe ZD2 connects positive supply and through connect+15V of resistance R 3.
The present invention takes above technical scheme, compared with prior art, has the following advantages: the characteristic of utilizing operational amplifier: input impedance is very large, and output impedance is very little, and open loop multiplication factor is very big.Input impedance is large, can be similar to the signal code of thinking regardless of flow sensor output, and make this signal code all flow through feedback resistance RF, obtains the output voltage signal of conversion at the output of amplifier.And the internal resistance of this voltage signal is exactly the output impedance of operational amplifier, because the output impedance of amplifier is very little, so load capacity is extremely strong, utilize again the amplification characteristic of amplifier to form a stable closed-loop system in conjunction with feedback resistance, the voltage signal of the conversion output making is not subject to the impact of post processing electric circuit, therefore can provide stable voltage signal for post-amplifier, and there will not be error; Reliable and stable through amplifier signal after treatment.
Below in conjunction with accompanying drawing, the invention will be further described with enforcement.
Brief description of the drawings
Accompanying drawing 1 is the circuit theory diagrams of preamplifier in the embodiment of the present invention.
Embodiment
Embodiment, as shown in Figure 1, the imported preamplifier of a kind of electric current, comprises operational amplifier, resistance R 1, resistance R 2, resistance R 3, feedback resistance RF, adjustable resistance RP, voltage stabilizing didoe ZD1, voltage stabilizing
Diode ZD2, diode D1, diode D2 and feedback capacity CF; The model of operational amplifier is OP-07,
The model of voltage stabilizing didoe ZD1, voltage stabilizing didoe ZD2 is RD5.1E.
One end of the positive pole of the anti-phase input termination diode D1 of operational amplifier, the negative pole of diode D2 and feedback capacity CF, resistance R 1, the negative pole of diode D1, the plus earth of diode D2, one end and the positive signal source of another termination feedback resistance RF of resistance R 1, the other end of another termination feedback capacity CF of feedback resistance RF and the output of operational amplifier, the positive input end grounding of operational amplifier, between two zeroing ends of operational amplifier, connect adjustable resistance RP, the movable contact spring of adjustable resistance RP connects the positive electricity of operational amplifier
Source.
The negative pole of voltage stabilizing didoe ZD1, the positive pole of voltage stabilizing didoe ZD2 connect negative signal source ground connection, the positive pole of voltage stabilizing didoe ZD1 connects negative supply and through connect-15V of resistance R 2, the negative pole of voltage stabilizing didoe ZD2 connects positive supply and through connect+15V of resistance R 3, the output of operational amplifier is positive output end, negative output terminal ground connection.
The imported preamplifier of this electric current claims again current-voltage converter, because this circuit inverting input is as hypothetically, virtual earth is worked, and can be used as the current measurement that input resistance is extremely low, also can be used as the imported preamplifier of various transducers, particularly electric current uses.
Circuit has removed the resistance of inverting input, and in anti-phase amplification, the work of circuit is all by Current Control, from the electric current I of signal source inflow
inbe sent to the output of operational amplifier, i.e. I
in=I
f.But to consider the input bias current I of operational amplifier as error component
b.
Current/voltage transfer principle is, adds feedback resistance RF at the I/O of operational amplifier, is just convertible into voltage E, E=-I
f× RF; RF can be by RF=E
o/ I
informula obtain.Suppose output voltage 1V, full scale input current I
in=1 μ A, RF=1 × 10
6Ω.
The resistance R 1 of operational amplifier inverting input series connection is current-limiting resistance, in the time of input overload, operational amplifier is played a protective role.
The effect of diode D1, diode D2 is to align reverse voltage to carry out clamp, so that it is unlikely excessive to be input to the differential voltage of operational amplifier.When circuit is worked normally, can think that they are imaginary earth point virtual earths, do not produce voltage.
The effect of feedback capacity Cf is the noise contribution of decaying wherein in the time of conversion weak current.But must note frequency response.Zero frequency f0 is by f0=1/2 π Cf*Rf(Hz) formula determine, in the time selecting, to coordinate mutually with required frequency.During for direct current, can adopt capacitor capacious to obtain storage effect.
The effect of voltage stabilizing didoe ZD1, voltage stabilizing didoe ZD2 is be stabilized to ± 5V of the supply voltage that makes operational amplifier, reduces power consumption, suppresses the temperature rise of chip internal, reduces bias current I
bincrement.If for can be ± 15V of circuit common supply voltage, at this moment should remove voltage stabilizing didoe ZD1, voltage stabilizing didoe ZD2 in circuit.
The input bias current of operational amplifier is little, lacks of proper care little.And there is external offset compensation.Adjustable resistance RP in circuit diagram adjusts the imbalance of compensated amplifier, can obtain the very accurate voltage signal corresponding with sensor current.
One skilled in the art would recognize that above-mentioned embodiment is exemplary, is in order to make those skilled in the art can better understand content of the present invention, to should not be understood as limiting the scope of the invention.Under the enlightenment of technical solution of the present invention, those skilled in the art can be without creative work, adopts alternate manner to realize object of the present invention, as long as the improvement of doing according to technical solution of the present invention, all falls into protection scope of the present invention.
Claims (3)
1. the imported preamplifier of electric current, is characterized in that: the imported preamplifier of described electric current comprises operational amplifier, feedback resistance RF, adjustable resistance RP, diode D1, diode D2 and feedback capacity CF;
The positive pole of the anti-phase input termination diode D1 of described operational amplifier, the negative pole of diode D2, one end and the positive signal source of feedback capacity CF, feedback resistance RF, the negative pole of diode D1, the plus earth of diode D2, the other end of another termination feedback capacity CF of feedback resistance RF and the output of operational amplifier, the positive input end grounding of operational amplifier, between two zeroing ends of operational amplifier, connect adjustable resistance RP, the movable contact spring of adjustable resistance RP connects the positive power source terminal of operational amplifier.
2. the imported preamplifier of a kind of electric current as claimed in claim 1, it is characterized in that: the imported preamplifier of described electric current also comprises resistance R 1, the inverting input of one termination operational amplifier of resistance R 1, one end and the positive signal source of another termination feedback capacity CF of resistance R 1.
3. the imported preamplifier of a kind of electric current as claimed in claim 1 or 2, is characterized in that: the imported preamplifier of described electric current also comprises resistance R 2, resistance R 3, voltage stabilizing didoe ZD1 and voltage stabilizing didoe ZD2;
The negative pole of described voltage stabilizing didoe ZD1, the positive pole of voltage stabilizing didoe ZD2 connect negative signal source ground connection, and the positive pole of voltage stabilizing didoe ZD1 connects negative supply and through connect-15V of resistance R 2, and the negative pole of voltage stabilizing didoe ZD2 connects positive supply and through connect+15V of resistance R 3.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410153577.6A CN103905007A (en) | 2014-04-17 | 2014-04-17 | Current input type pre-amplifier |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410153577.6A CN103905007A (en) | 2014-04-17 | 2014-04-17 | Current input type pre-amplifier |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN103905007A true CN103905007A (en) | 2014-07-02 |
Family
ID=50996185
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201410153577.6A Pending CN103905007A (en) | 2014-04-17 | 2014-04-17 | Current input type pre-amplifier |
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| Country | Link |
|---|---|
| CN (1) | CN103905007A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113219309A (en) * | 2021-04-14 | 2021-08-06 | 深圳供电局有限公司 | Partial discharge detection device |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1512663A (en) * | 2002-12-27 | 2004-07-14 | 三美电机株式会社 | Current feedback circuit |
| CN1912551A (en) * | 2006-08-18 | 2007-02-14 | 江苏伟屹电子有限公司 | Vortex street signal amplification method of vortex street flowmeter |
-
2014
- 2014-04-17 CN CN201410153577.6A patent/CN103905007A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1512663A (en) * | 2002-12-27 | 2004-07-14 | 三美电机株式会社 | Current feedback circuit |
| CN1912551A (en) * | 2006-08-18 | 2007-02-14 | 江苏伟屹电子有限公司 | Vortex street signal amplification method of vortex street flowmeter |
Non-Patent Citations (1)
| Title |
|---|
| 常玉燕，吕光译: "《日本电子电路精选》", 31 December 1989, 北京：电子工业出版社 * |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113219309A (en) * | 2021-04-14 | 2021-08-06 | 深圳供电局有限公司 | Partial discharge detection device |
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| PB01 | Publication | ||
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Application publication date: 20140702 |