CN107565917A - A kind of intelligent small voltage measuring and amplifying circuit - Google Patents
A kind of intelligent small voltage measuring and amplifying circuit Download PDFInfo
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- CN107565917A CN107565917A CN201711030947.7A CN201711030947A CN107565917A CN 107565917 A CN107565917 A CN 107565917A CN 201711030947 A CN201711030947 A CN 201711030947A CN 107565917 A CN107565917 A CN 107565917A
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- resistance
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- operational amplifier
- amplifying circuit
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Abstract
The present invention provides a kind of intelligent small voltage measuring and amplifying circuit, and the circuit is made up of filter circuit, negative-feedback circuit and symmetrical amplifying circuit.Described filtered electrical routing resistance R1 and R2, electric capacity C1 composition, described negative-feedback circuit are made up of operational amplifier A 1 and resistance R3 and R4, and described symmetrical amplifying circuit is made up of operational amplifier A 2, A3, A4, resistance R5 ~ R11.The voltage measurement amplification circuit structure is simple, cost is cheap, it is possible to reduce the common mode disturbance voltage of equivalent inpnt, improves common-mode rejection ratio, effective suppression circuit temperature drift, null offset and common-mode noise.
Description
Technical field
The invention belongs to electric and electronic technical field, more particularly to a kind of intelligent small voltage measuring and amplifying circuit.
Background technology
The key component for the electronic measuring instrument for being various different purposes is amplified to ultra-weak electronic signal --- preceding storing
The task of big device.The sensitivity of preamplifier is mainly influenceed by following factor：The output of ultra-weak electronic signal output circuit
Impedance (typically changing, influence whether the voltage amplification factor of amplifying circuit below), amplifier ambient noise in itself, put
The input imbalance of big device and drift, common mode inhibition capacity etc.；Therefore, improve measuring instrument frontend amplifying circuit input impedance and
Common mode inhibition capacity is vital.
Pre-amplification circuit generally selects all very high circuit of input impedance and common-mode rejection ratio.Field effect transistor amplification circuit
Input impedance with operational amplification circuit is larger, but FET circuit can not suppress to common mode disturbances, therefore multiselect
Use operation amplifier circuit.The quality of measuring instrument performance depends greatly on the performance of its frontend amplifying circuit, often
Operational amplification circuit and instrument amplifier circuit of the selection with compared with very noisy rejection ability and larger input impedance.In small voltage
Accurate measurement when, the symmetry of instrument amplifier circuit is difficult to be completely secured, in the environment of very noisy, in instrument amplifier circuit
The middle negative-feedback circuit for adding common-mode voltage can offset common-mode noise or a part therein；In long distance signal transmission,
Circuit input end, which adds follower circuit, can overcome input circuit caused by because measurement cable is longer uneven and draw well
The measurement error entered.
The content of the invention
In view of the above-mentioned drawbacks of the prior art and insufficient, it is an object of the present invention to provide a kind of intelligent small
Voltage measurement amplifying circuit, intelligent small voltage measuring and amplifying circuit of the invention can reduce the common mode disturbances of equivalent inpnt
Voltage, improve common-mode rejection ratio, effective suppression circuit temperature drift, null offset and common-mode noise.
In order to realize above-mentioned task, the present invention uses following technical solution：
A kind of intelligent small voltage measuring and amplifying circuit, including filter circuit, negative-feedback circuit and symmetrical amplifying circuit,
Described filtered electrical routing resistance R1 and R2, electric capacity C1 composition, described resistance R1 are connected to signal input part In1 and electric capacity C1
Between, described resistance R2 is connected between signal input part In2 and electric capacity C1；Described negative-feedback circuit is put by computing
Big device A1 and resistance R3 and R4 composition, the output end of described operational amplifier A 1 are connected with resistance R2, operational amplifier A 1
Negative input end be connected with output end, described resistance R3 be connected on A1 positive input terminal and operational amplifier A 2 positive input terminal it
Between, described resistance R4 is connected between resistance R3 and the negative input end of operational amplifier A 3；Described symmetrical amplifying circuit and letter
Number output end Out is connected；Described symmetrical amplifying circuit is made up of operational amplifier A 2, A3, A4, resistance R5~R10, described
Operational amplifier A 4 is connected with signal output part Out, described resistance R5 concatenation operation amplifiers A2 output end and positive input
Between end, described resistance R6 is connected between A2 positive input terminal and A3 negative input end, and described resistance R7 is connected on computing
Between amplifier A3 output end and negative input end, described resistance R8 is connected between A2 output end and resistance R10, described
Resistance R9 is connected between resistance R7 and the positive input terminal of operational amplifier A 4, and the resistance R10 is connected on the negative of operational amplifier A 4
Between input and output end, the resistance R11 is connected between resistance R9 and ground.
The beneficial effects of the invention are as follows：
The structure of symmetrical amplifying circuit is full symmetric.Symmetric circuit refers to two wires and its company in two-wire circuit
All circuits connect all have identical impedance (circuit balancing) over the ground or to other wires.The purpose of circuit symmetrical is to make this
The noise that two wires are detected is equal, and noise now is common-mode noise, can be in symmetrically cancel themselves in load.If again
Noise and interference can be further reduced with reference to shielding protection.Symmetrical amplifying circuit is by 3 pieces of integrated transporting dischargings and non-essential resistance structure
Into (also known as three discharge circuits).Whole circuit composition dual-stage amplifier.The first order is A2, A3 amplifier and resistance R5, R6 and R7 group
Into the same difference amplifier that is in parallel, the second level is the subtracter that amplifier A4 and resistance R8, R9, R10 and R11 are formed.Preferably
Subtracter only amplifies In1, In2 differential-mode portion, and it is changed into Single-end output after double-width grinding signal is amplified, and is put with adapting to rear class
The requirement of big device.In order to ensure to have sufficiently large common-mode rejection ratio, the resistance of the circuit need to meet symmetric condition：R1=R2, R3
=R4, R5=R6.For the difference voltage (differential mode voltage) of two inputs of amplifier, the differential mode voltage gain of circuit can reach
The numerical value larger to one, and regulation outer meeting resistance R6 can easily change the size of differential mode voltage gain.It can be seen that circuit is put
Big difference mode signal can suppression common mode signal, differential mode multiplication factor is bigger, and common-mode rejection ratio is bigger.Instrument symmetrical amplifying circuit
Structure is strict to the tolerance of peripheral cell in actual applications, and the parameter such as resistance, the length for measuring line needs full symmetric
It also is difficult to accomplish；Therefore, the instrument amplifier circuit with common-mode voltage negative-feedback can be used, to make up above-mentioned instrument amplifier circuit
Deficiency.Further to improve the common-mode rejection ratio of circuit, the negative-feedback circuit of common-mode voltage can be added in foregoing circuit, with
Offset common-mode noise or a part therein.
The voltage measurement amplification circuit structure is simple, cost is cheap, it is possible to reduce the common mode disturbance voltage of equivalent inpnt, carries
High cmrr, effective suppression circuit temperature drift, null offset and common-mode noise.
Brief description of the drawings
The present invention is further explained below in conjunction with the drawings and specific embodiments.
Fig. 1 is small voltage measuring and amplifying circuit theory diagrams.
In Fig. 1, A1~A4 is high input impedance operational amplifier OPA2335, and R1~R11 is precision resister, and C1 is filter
Ripple electric capacity.
Embodiment
If Fig. 1 is small voltage measuring and amplifying circuit, the circuit is by filter circuit, negative-feedback circuit and symmetrical amplifying circuit
Composition, described filtered electrical routing resistance R1 and R2, electric capacity C1 composition, described resistance R1 be connected to signal input part In1 with
Between electric capacity C1, described resistance R2 is connected between signal input part In2 and electric capacity C1；Described negative-feedback circuit by
Operational amplifier A 1 and resistance R3 and R4 composition, the output end of described operational amplifier A 1 are connected with resistance R2, and computing is put
Big device A1 negative input end is connected with output end, and described resistance R3 is connected on the just defeated of A1 positive input terminal and operational amplifier A 2
Between entering end, described resistance R4 is connected between resistance R3 and the negative input end of operational amplifier A 3；Described symmetrical amplification electricity
Road is connected with signal output part Out；Described symmetrical amplifying circuit is made up of operational amplifier A 2, A3, A4, resistance R5~R10,
Described operational amplifier A 4 is connected with signal output part Out, described resistance R5 concatenation operation amplifiers A2 output end with
Between positive input terminal, described resistance R6 is connected between A2 positive input terminal and A3 negative input end, and described resistance R7 connects
Between the output end of operational amplifier A 3 and negative input end, described resistance R8 is connected between A2 output end and resistance R10,
Described resistance R9 is connected between resistance R7 and the positive input terminal of operational amplifier A 4, and the resistance R10 is connected on operational amplifier
Between A4 negative input end and output end, the resistance R11 is connected between resistance R9 and ground.
Increase a follower circuit being made up of amplifier A4 in the input of measuring amplifier, measured signal is being transmitted
When, the output end of follower is connected with the screen layer of signal-transmitting cable, makes the screen layer current potential follow-up amplifier of cable defeated
Enter the common mode potential change at end, i.e. cable shield is identical with amplifier in common mode current potential, and then common-mode signal is being leaked electricity
The tool as caused by common-mode signal through partial pressure is just not present in partial pressure event resolves in resistance and distribution capacity, measuring amplifier input
There is the voltage of differential mode feature, so as to reach the common mode disturbance voltage for reducing equivalent inpnt, improve the common mode of whole measuring circuit
Rejection ability.
Claims (2)
1. a kind of intelligent small voltage measuring and amplifying circuit, it is characterised in that put by filter circuit, negative-feedback circuit and symmetrically
Big circuit composition；Described filtered electrical routing resistance R1 and R2, electric capacity C1 composition, described resistance R1 are connected to signal input part
Between In1 and electric capacity C1, described resistance R2 is connected between signal input part In2 and electric capacity C1；Described negative-feedback
Circuit is made up of operational amplifier A 1 and resistance R3 and R4, and the output end of described operational amplifier A 1 is connected with resistance R2,
The negative input end of operational amplifier A 1 is connected with output end, and described resistance R3 is connected on A1 positive input terminal and operational amplifier A 2
Positive input terminal between, described resistance R4 is connected between resistance R3 and the negative input end of operational amplifier A 3；Described is symmetrical
Amplifying circuit is connected with signal output part Out.
2. a kind of intelligent small voltage measuring and amplifying circuit as claimed in claim 1, it is characterised in that described symmetrically puts
Big circuit is made up of operational amplifier A 2, A3, A4, resistance R5~R11, described operational amplifier A 4 and signal output part Out
It is connected, between described resistance R5 concatenation operation amplifiers A2 output end and positive input terminal, described resistance R6 is connected to A2
Positive input terminal and A3 negative input end between, described resistance R7 be connected on the output end of operational amplifier A 3 and negative input end it
Between, described resistance R8 is connected between A2 output end and resistance R10, and described resistance R9 is connected on resistance R7 and operational amplifier
Between A4 positive input terminal, the resistance R10 is connected between negative input end and the output end of operational amplifier A 4, the resistance
R11 is connected between resistance R9 and ground.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201711030947.7A CN107565917A (en) | 2017-10-28 | 2017-10-28 | A kind of intelligent small voltage measuring and amplifying circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201711030947.7A CN107565917A (en) | 2017-10-28 | 2017-10-28 | A kind of intelligent small voltage measuring and amplifying circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN107565917A true CN107565917A (en) | 2018-01-09 |
Family
ID=61032008
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201711030947.7A Pending CN107565917A (en) | 2017-10-28 | 2017-10-28 | A kind of intelligent small voltage measuring and amplifying circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN107565917A (en) |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN201349199Y (en) * | 2009-01-19 | 2009-11-18 | 深圳市同洲电子股份有限公司 | Amplification circuit |
| CN202524364U (en) * | 2012-05-11 | 2012-11-07 | 四川优的科技有限公司 | Double operational amplifier band-pass active filter |
| CN103684297A (en) * | 2013-12-03 | 2014-03-26 | 成都国科海博信息技术股份有限公司 | Electric amplifying circuit used for detector |
| CN203933538U (en) * | 2014-05-13 | 2014-11-05 | 徐云鹏 | A kind of intelligent small voltage is measured amplifying circuit |
-
2017
- 2017-10-28 CN CN201711030947.7A patent/CN107565917A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN201349199Y (en) * | 2009-01-19 | 2009-11-18 | 深圳市同洲电子股份有限公司 | Amplification circuit |
| CN202524364U (en) * | 2012-05-11 | 2012-11-07 | 四川优的科技有限公司 | Double operational amplifier band-pass active filter |
| CN103684297A (en) * | 2013-12-03 | 2014-03-26 | 成都国科海博信息技术股份有限公司 | Electric amplifying circuit used for detector |
| CN203933538U (en) * | 2014-05-13 | 2014-11-05 | 徐云鹏 | A kind of intelligent small voltage is measured amplifying circuit |
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Application publication date: 20180109 |