CN203933538U - A kind of intelligent small voltage is measured amplifying circuit - Google Patents
A kind of intelligent small voltage is measured amplifying circuit Download PDFInfo
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- CN203933538U CN203933538U CN201420242920.XU CN201420242920U CN203933538U CN 203933538 U CN203933538 U CN 203933538U CN 201420242920 U CN201420242920 U CN 201420242920U CN 203933538 U CN203933538 U CN 203933538U
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Abstract
The utility model discloses a kind of intelligent small voltage and measure amplifying circuit, this circuit is comprised of filter circuit, negative-feedback circuit and symmetrical amplifying circuit.Described filter circuit is comprised of resistance R 1 and R2, capacitor C 1, and described negative-feedback circuit is comprised of operational amplifier A 1 and resistance R 3 and R4, and described symmetrical amplifying circuit is comprised of operational amplifier A 2, A3, A4, resistance R 5 ~ R11.This voltage measurement amplification circuit structure is simple, with low cost, can reduce the common mode disturbance voltage of equivalence input, improves common-mode rejection ratio, effectively suppresses circuit temperature drift, null offset and common-mode noise.
Description
Technical field
The utility model belongs to electric and electronic technical field, relates in particular to a kind of intelligent small voltage and measures amplifying circuit.
Background technology
Ultra-weak electronic signal is amplified to the key component of the electronic measuring instrument that is various different purposes---the task of preamplifier.The sensitivity of preamplifier is mainly subject to the impact of following factor: the output impedance of ultra-weak electronic signal output circuit (normally change, can have influence on the voltage amplification factor of amplifying circuit below), the background noise of amplifier itself are, input imbalance and drift, the common mode inhibition capacity etc. of amplifier; Therefore, input impedance and the common mode inhibition capacity of raising measuring instrument frontend amplifying circuit are vital.
Pre-amplification circuit is selected all very high circuit of input impedance and common-mode rejection ratio conventionally.The input impedance of field effect transistor amplification circuit and operational amplification circuit is all larger, but field effect transistor circuit can not suppress common mode disturbances, so multiselect operation amplifier circuit.The quality of measuring instrument performance depends on the performance of its frontend amplifying circuit to a great extent, and normal selection has operational amplification circuit and the instrument amplifying circuit that suppresses ability and larger input impedance compared with very noisy.When the accurate measurement of small voltage, instrument is difficult to guarantee completely by the symmetry of amplifying circuit, in the environment of very noisy, at instrument, with the negative-feedback circuit that adds common-mode voltage in amplifying circuit, can offsets common-mode noise or a part wherein; When long range signals transmits, at circuit input end, add follower circuit can overcome well owing to measuring cable compared with the uneven measure error of introducing of the long input circuit causing.
Summary of the invention
The defect and the deficiency that for above-mentioned prior art, exist, the purpose of this utility model is, provide a kind of intelligent small voltage to measure amplifying circuit, intelligent small voltage of the present utility model is measured the common mode disturbance voltage that amplifying circuit can reduce equivalence input, improve common-mode rejection ratio, effectively suppress circuit temperature drift, null offset and common-mode noise.
In order to realize above-mentioned task, the utility model adopts following technical solution:
A kind of intelligent small voltage is measured amplifying circuit, comprise filter circuit, negative-feedback circuit and symmetrical amplifying circuit, described filter circuit is comprised of resistance R 1 and R2, capacitor C 1, described resistance R 1 be connected to signal input part In1 and capacitor C 1 between, described resistance R 2 be connected to signal input part In2 and capacitor C 1 between, described negative-feedback circuit is comprised of operational amplifier A 1 and resistance R 3 and R4, the output of described operational amplifier A 1 is connected with resistance R 2, the negative input end of operational amplifier A 1 is connected with output, described resistance R 3 is connected between the positive input terminal of A1 and the positive input terminal of operational amplifier A 2, and described resistance R 4 is connected between resistance R 3 and the negative input end of operational amplifier A 3, described symmetrical amplifying circuit is connected with signal output part Out, described symmetrical amplifying circuit is by operational amplifier A 2, A3, A4, resistance R 5 ~ R10 forms, described operational amplifier A 4 is connected with signal output part Out, between the output and positive input terminal of described resistance R 5 concatenation operation amplifier A2, described resistance R 6 is connected between the positive input terminal of A2 and the negative input end of A3, described resistance R 7 is connected between the output and negative input end of operational amplifier A 3, described resistance R 8 is connected between the output and resistance R 10 of A2, described resistance R 9 is connected between resistance R 7 and the positive input terminal of operational amplifier A 4, described resistance R 10 is connected between the negative input end and output of operational amplifier A 4, described resistance R 11 is connected between resistance R 9 and ground.
The beneficial effects of the utility model are:
The structure of symmetrical amplifying circuit is full symmetric.Symmetric circuit refers to that two wires in two-wire circuit and all circuit of connection thereof all have identical impedance (circuit balancing) over the ground or to other wires.The object of circuit symmetrical is to make the noise that these two wires detect to equate, noise is now common-mode noise, can in symmetrical load, offset voluntarily.If can further reduce Noise and Interference in conjunction with shielding protection again.Symmetrical amplifying circuit forms (claiming again three discharge circuits) by 3 integrated transporting dischargings and non-essential resistance.Whole the electric circuit constitute dual-stage amplifier.The first order is the same differential amplifier that is in parallel that A2, A3 amplifier and resistance R 5, R6 and R7 form, and the second level is the subtracter that amplifier A4 and resistance R 8, R9, R10 and R11 form.Desirable subtracter only amplifies the differential mode part of In1, In2, and it becomes Single-end output after both-end input signal is amplified, to adapt to the requirement of post-amplifier.In order to ensure enough large common-mode rejection ratio, the resistance of this circuit need meet symmetric condition: R1=R2, R3=R4, R5=R6.For the difference voltage (differential mode voltage) of two inputs of amplifier, the gain of the differential mode voltage of circuit can reach a larger numerical value, and regulates outer meeting resistance R6 can change easily the size of differential mode voltage gain.Visible, circuit amplifies difference mode signal can suppress common-mode signal, and differential mode multiplication factor is larger, and common-mode rejection ratio is larger.Instrument is strict to the tolerance of peripheral cell in actual applications by the structure of symmetrical amplifying circuit, and the parameters such as length of resistance, slotted line need full symmetric to be also difficult to accomplish; Therefore, can adopt the degenerative instrument amplifying circuit of band common-mode voltage, to make up the deficiency of amplifying circuit for above-mentioned instrument.For further improving the common-mode rejection ratio of circuit, can in foregoing circuit, add the negative-feedback circuit of common-mode voltage, to offset common-mode noise or a part wherein.
This voltage measurement amplification circuit structure is simple, with low cost, can reduce the common mode disturbance voltage of equivalence input, improves common-mode rejection ratio, effectively suppresses circuit temperature drift, null offset and common-mode noise.
Accompanying drawing explanation
Below in conjunction with the drawings and specific embodiments the utility model is further explained explanation.
Fig. 1 is that small voltage is measured amplifying circuit schematic diagram.
In Fig. 1, A1 ~ A4 is high input impedance operational amplifier OPA2335, and R1 ~ R11 is precision resister, and C1 is filter capacitor.
Embodiment
If Fig. 1 is that small voltage is measured amplifying circuit, this circuit is comprised of filter circuit, negative-feedback circuit and symmetrical amplifying circuit, described filter circuit is comprised of resistance R 1 and R2, capacitor C 1, described resistance R 1 be connected to signal input part In1 and capacitor C 1 between, described resistance R 2 be connected to signal input part In2 and capacitor C 1 between, described negative-feedback circuit is comprised of operational amplifier A 1 and resistance R 3 and R4, the output of described operational amplifier A 1 is connected with resistance R 2, the negative input end of operational amplifier A 1 is connected with output, described resistance R 3 is connected between the positive input terminal of A1 and the positive input terminal of operational amplifier A 2, and described resistance R 4 is connected between resistance R 3 and the negative input end of operational amplifier A 3, described symmetrical amplifying circuit is connected with signal output part Out, described symmetrical amplifying circuit is by operational amplifier A 2, A3, A4, resistance R 5 ~ R10 forms, described operational amplifier A 4 is connected with signal output part Out, between the output and positive input terminal of described resistance R 5 concatenation operation amplifier A2, described resistance R 6 is connected between the positive input terminal of A2 and the negative input end of A3, described resistance R 7 is connected between the output and negative input end of operational amplifier A 3, described resistance R 8 is connected between the output and resistance R 10 of A2, described resistance R 9 is connected between resistance R 7 and the positive input terminal of operational amplifier A 4, described resistance R 10 is connected between the negative input end and output of operational amplifier A 4, described resistance R 11 is connected between resistance R 9 and ground.
Input at measuring amplifier increases a follower circuit being comprised of amplifier A4, measured signal is when transmission, the screen of the output of follower and signal-transmitting cable is joined, make the common mode potential change of the screen current potential follow-up amplifier input of cable, be that cable shield is identical with amplifier in common mode current potential, so the dividing potential drop effect of common-mode signal on ohmic leakage and distributed capacitance disappears, just there is not the voltage with differential mode feature being produced through dividing potential drop by common-mode signal in measuring amplifier input, thereby reach the common mode disturbance voltage that reduces equivalence input, improved the common mode inhibition capacity of whole measuring circuit.
Claims (2)
1. intelligent small voltage is measured an amplifying circuit, it is characterized in that, filter circuit, negative-feedback circuit and symmetrical amplifying circuit, consists of; Described filter circuit is comprised of resistance R 1 and R2, capacitor C 1, described resistance R 1 be connected to signal input part In1 and capacitor C 1 between, described resistance R 2 be connected to signal input part In2 and capacitor C 1 between; Described negative-feedback circuit is comprised of operational amplifier A 1 and resistance R 3 and R4, the output of described operational amplifier A 1 is connected with resistance R 2, the negative input end of operational amplifier A 1 is connected with output, described resistance R 3 is connected between the positive input terminal of A1 and the positive input terminal of operational amplifier A 2, and described resistance R 4 is connected between resistance R 3 and the negative input end of operational amplifier A 3; Described symmetrical amplifying circuit is connected with signal output part Out.
2. a kind of intelligent small voltage as claimed in claim 1 is measured amplifying circuit, it is characterized in that, described symmetrical amplifying circuit is by operational amplifier A 2, A3, A4, resistance R 5 ~ R11 forms, described operational amplifier A 4 is connected with signal output part Out, between the output and positive input terminal of described resistance R 5 concatenation operation amplifier A2, described resistance R 6 is connected between the positive input terminal of A2 and the negative input end of A3, described resistance R 7 is connected between the output and negative input end of operational amplifier A 3, described resistance R 8 is connected between the output and resistance R 10 of A2, described resistance R 9 is connected between resistance R 7 and the positive input terminal of operational amplifier A 4, described resistance R 10 is connected between the negative input end and output of operational amplifier A 4, described resistance R 11 is connected between resistance R 9 and ground.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420242920.XU CN203933538U (en) | 2014-05-13 | 2014-05-13 | A kind of intelligent small voltage is measured amplifying circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420242920.XU CN203933538U (en) | 2014-05-13 | 2014-05-13 | A kind of intelligent small voltage is measured amplifying circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN203933538U true CN203933538U (en) | 2014-11-05 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN201420242920.XU Expired - Fee Related CN203933538U (en) | 2014-05-13 | 2014-05-13 | A kind of intelligent small voltage is measured amplifying circuit |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105915187A (en) * | 2016-04-11 | 2016-08-31 | 成都瑞途电子有限公司 | Temperature signal acquisition amplifier |
| CN107565917A (en) * | 2017-10-28 | 2018-01-09 | 成都优力德新能源有限公司 | A kind of intelligent small voltage measuring and amplifying circuit |
-
2014
- 2014-05-13 CN CN201420242920.XU patent/CN203933538U/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105915187A (en) * | 2016-04-11 | 2016-08-31 | 成都瑞途电子有限公司 | Temperature signal acquisition amplifier |
| CN105915187B (en) * | 2016-04-11 | 2018-10-16 | 黄伟 | Temperature signal collection amplifier |
| CN107565917A (en) * | 2017-10-28 | 2018-01-09 | 成都优力德新能源有限公司 | A kind of intelligent small voltage measuring and amplifying circuit |
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| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20141105 Termination date: 20150513 |
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| EXPY | Termination of patent right or utility model |