A kind of low level signal amplification measuring circuitTechnical field
The invention belongs to high-precision meter technical field, more particularly to a kind of low level signal amplification measuring circuit.
Background technology
In computer measurement system, the non-electric charge quantity signallings such as some pressure, temperature, acceleration often will be gathered, the method that the measurement of this kind of signal generally adopts is, using sensor, these non-electrical signals are become voltage or current signal, but because sensor output impedance is high, voltage signal all very littles (mv level) of output, work under bad environment is it is therefore desirable to a kind of measuring circuit has high input impedance in addition, high cmrr, the features such as high stability, the linearity are good.
Content of the invention
The present invention is aiming at the problems referred to above, makes up the deficiencies in the prior art, provides a kind of low level signal amplification measuring circuit；The present invention can reach one of percentage precision, and this circuit also has the features such as suppression common mode interference, suppression temperature drift, good stability, strong interference immunity in addition.
For realizing the above-mentioned purpose of the present invention, the present invention adopts the following technical scheme that.
A kind of present invention low level signal amplification measuring circuit, including signal input module, voltage amplifier circuit, Sai Lin more wave filter, voltage follower circuit, isolation circuit, rear class acquisition system；Its structural feature is: the outfan of described signal input module connects the input of voltage amplifier circuit, the input of the outfan connection plug woods more wave filter of voltage amplifier circuit, the outfan of Sai Lin more wave filter connects the input of voltage follower circuit, the outfan of voltage follower circuit connects the input of isolation circuit, and the outfan of isolation circuit connects the input of rear class acquisition system.
As a preferred embodiment of the present invention, described voltage amplifier circuit adopts high-precision amplifying ad623b and ad824 cascade to constitute, resistance r1 is connected between 1 pin of described ad623b and 8 pins, the 4 pin ground connection of described ad623b, 5 pins of described ad623b connect negative input 6 pin and outfan 7 pin of ad824；Electrode input end 5 pin of described ad824 connects one end of resistance r17 and r18, the other end ground connection of described resistance r18.
Another kind of preferred version as the present invention, the input in positive pole of described plug woods more wave filter connects the positive terminal of power supply v3 and one end of resistance r1 respectively, the other end of resistance r1 connects one end of resistance r2 and one end of electric capacity c1 respectively, the other end of resistance r2 connects one end of electric capacity c2 and positive terminal 3 pin of amplifier lm124ad respectively, the other end of electric capacity c2 and the negative pole end common ground of power supply v3,1 pin ground connection of amplifier lm124ad, 4 pins are connected with the positive terminal of power supply v1；The outfan of described amplifier lm124ad is connected with the outfan out positive pole of plug woods more wave filter, negative pole end 2 pin of the other end of described electric capacity c1 and amplifier lm124ad is connected with the outfan out positive pole of plug woods more wave filter jointly, the input in negative pole of described amplifier lm124ad and outfan out negative pole common ground.
As another kind of preferred version of the present invention, described isolation circuit adopts optical coupling isolation circuit, and described optical coupling isolation circuit includes high-linearity analogy optocoupler hcnr201, resistance r8, r9, r16, the first amplifier ad824, the second amplifier ad824, electric capacity c19, c20；One end of described resistance r8 connects input in, the other end is connected with the negative input of the first amplifier ad824, the other end of resistance r8 is also respectively connected with 3 pins of one end of electric capacity c19, hcnr201, the outfan of the first amplifier ad824 is connected with the other end of electric capacity c19, one end of r9 is connected, and the other end of resistance r9 is connected with 1 pin of hcnr201；6 pins of described high-linearity analogy optocoupler hcnr201 respectively with electric capacity c20, resistance r16, the second amplifier ad824 2 pins, 5 pins of described hcnr201 are connected with 3 pins of the second amplifier ad824, and electric capacity c20, the other end of resistance r16 are connected with 1 pin of the second amplifier ad824 jointly.
The invention has the beneficial effects as follows.
A kind of present invention low level signal amplification measuring circuit, measurement by magnification circuit with high-precision meter amplifier ad623 as core devices, achieve the accurate amplification to voltage signal in the range of 0mv～25mv, adopt high-linearity analogy optocoupler hcnr201 simultaneously, the impact to collection terminal for the isolation measurement end, this low level signal amplification measuring circuit can reach one of percentage precision, and this circuit also has the features such as suppression common mode interference, suppression temperature drift, good stability, strong interference immunity in addition.
The present invention can accurately can amplify to weak voltage signals in the range of 0～25mv, and reaches 1% precision, efficiently solves the problem that faint small-signal can not accurately measure in adverse circumstances；Measuring system of the present invention can be widely applied to degree of stability, certainty of measurement are required in higher analog acquisition circuit.
Brief description
Fig. 1 is a kind of the general frame of present invention low level signal amplification measuring circuit.
Fig. 2 is a kind of voltage amplifier circuit connection figure of present invention low level signal amplification measuring circuit system.
Fig. 3 is a kind of circuit connection diagram of the Sai Lin more wave filter of present invention low level signal amplification measuring circuit system.
Fig. 4 is a kind of optical coupling isolation circuit of present invention low level signal amplification measuring circuit system.
Specific embodiment
As shown in figure 1, the general frame for a kind of present invention low level signal amplification measuring circuit.In figure, including signal input module, voltage amplifier circuit, Sai Lin more wave filter, voltage follower circuit, isolation circuit, rear class acquisition system；Its structural feature is: the outfan of described signal input module connects the input of voltage amplifier circuit, the input of the outfan connection plug woods more wave filter of voltage amplifier circuit, the outfan of Sai Lin more wave filter connects the input of voltage follower circuit, the outfan of voltage follower circuit connects the input of isolation circuit, and the outfan of isolation circuit connects the input of rear class acquisition system.
As shown in Fig. 2 the voltage amplifier circuit connection figure for a kind of present invention low level signal amplification measuring circuit system.As can be seen from Figure, described voltage amplifier circuit adopts high-precision amplifying ad623b and ad824 cascade to constitute, resistance r1 is connected between 1 pin of described ad623b and 8 pins, the 4 pin ground connection of described ad623b, 5 pins of described ad623b connect negative input 6 pin and outfan 7 pin of ad824；Electrode input end 5 pin of described ad824 connects one end of resistance r17 and r18, the other end ground connection of described resistance r18.
As shown in figure 3, the circuit connection diagram of the Sai Lin more wave filter for a kind of present invention low level signal amplification measuring circuit system.The input in positive pole of described plug woods more wave filter connects the positive terminal of power supply v3 and one end of resistance r1 respectively, the other end of resistance r1 connects one end of resistance r2 and one end of electric capacity c1 respectively, the other end of resistance r2 connects one end of electric capacity c2 and positive terminal 3 pin of amplifier lm124ad respectively, the other end of electric capacity c2 and the negative pole end common ground of power supply v3,1 pin ground connection of amplifier lm124ad, 4 pins are connected with the positive terminal of power supply v1；The outfan of described amplifier lm124ad is connected with the outfan out positive pole of plug woods more wave filter, negative pole end 2 pin of the other end of described electric capacity c1 and amplifier lm124ad is connected with the outfan out positive pole of plug woods more wave filter jointly, the input in negative pole of described amplifier lm124ad and outfan out negative pole common ground.
As shown in figure 4, the optical coupling isolation circuit for a kind of present invention low level signal amplification measuring circuit system.Described isolation circuit adopts optical coupling isolation circuit, and described optical coupling isolation circuit includes high-linearity analogy optocoupler hcnr201, resistance r8, r9, r16, the first amplifier ad824, the second amplifier ad824, electric capacity c19, c20；One end of described resistance r8 connects input in, the other end is connected with the negative input of the first amplifier ad824, the other end of resistance r8 is also respectively connected with 3 pins of one end of electric capacity c19, hcnr201, the outfan of the first amplifier ad824 is connected with the other end of electric capacity c19, one end of r9 is connected, and the other end of resistance r9 is connected with 1 pin of hcnr201；6 pins of described high-linearity analogy optocoupler hcnr201 respectively with electric capacity c20, resistance r16, the second amplifier ad824 2 pins, 5 pins of described hcnr201 are connected with 3 pins of the second amplifier ad824, and electric capacity c20, the other end of resistance r16 are connected with 1 pin of the second amplifier ad824 jointly.
It is understandable that, above with respect to the specific descriptions of the present invention, it is merely to illustrate the present invention and is not limited to the technical scheme described by the embodiment of the present invention, it will be understood by those within the art that, still the present invention can be modified or equivalent, to reach identical technique effect；As long as meeting and using needs, all within protection scope of the present invention.