CN206099914U - Lock -in amplifier - Google Patents
Lock -in amplifier Download PDFInfo
- Publication number
- CN206099914U CN206099914U CN201621164329.2U CN201621164329U CN206099914U CN 206099914 U CN206099914 U CN 206099914U CN 201621164329 U CN201621164329 U CN 201621164329U CN 206099914 U CN206099914 U CN 206099914U
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- China
- Prior art keywords
- resistance
- amplifier
- phase
- lock
- operational amplifier
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Abstract
The utility model discloses a lock -in amplifier, including a resistive voltage divider network, the 2nd resistive voltage divider network, adder, band pass filter, phase sensitive detector, low pass filter, moving looks ware and sampling and display circuit, interfering signal divides into two the tunnel after the reference signal input enter into lock -in amplifier through a resistive voltage divider network in, gets into through the 2nd resistive voltage divider network all the way, gets into all the way in addition move the looks ware, the output that moves the looks ware with phase sensitive detector links to each other. The utility model discloses a lock -in amplifier has realized faint signal amplitude's under the very noisy background detection betterly, mainly studies to the phase sensitivity detection technique in the weak signal detection method, and to back and sinusoidal interfering signal are enlargied to the noise source stack, decay, filtering, detection, the sampling of last AD is handled and is shown, constitutes one set of complete locking magnification system.
Description
Technical field
This utility model is related to the technical field of signal detection, more particularly to a kind of lock-in amplifier.
Background technology
Detection of Weak Signals be the signal extraction being submerged in noise out, the method for detection has a many kinds, but no matter
Which kind of method, is all distinguishing signal and noise using certain species diversity of signal and noise.For example, if signal has certain special
Property, and noise does not have this characteristic, then the characteristic that just this signal can be utilized exclusive separates noise and signaling zone
Come；Sometimes the monopolizing characteristic of signal is not obvious in time domain, and that just converts the signal into other domains and is analyzed, find out noise and
The difference of signal, for example, wavelet transformation is namely based on such thought and signal is extracted from noise.But, if signal does not have
Standby such monopolizing characteristic, such as signal band and noise band are overlapped, then be impossible to solve using simple filtering technique
Problem, may not also be proved effective using arrowband technology merely, in such a case, it is possible to artificially give signal certain characteristic,
Recycle this characteristic to distinguish the signal and noise that are exaggerated.This kind of signal has to pass through amplification, due to small-signal itself
Fluctuation, background and amplifier noise impact, measurement sensitivity is restricted.The preposition amplification for needing noise coefficient as far as possible little
Device, and according to source impedance and operating frequency utility model best match；Need to develop and be adapted to faint Cleaning Principle and spy can be met
The different device for needing；The characteristics of using electronics and information-theoretical method, studying the origin cause of formation and rule of noise, signal Analysis and phase
Dry relation.Since nineteen twenty-eight finds that the thermal agitation of electronics in resistance causes non-periodic voltage, weak detection technique is subject to general
Developed rapidly all over attention.Existing small-signal lock-in amplifier still has acquisition precision not enough, not can determine that
The quality of institute's detection signal, system can only meet particular case under detection the shortcomings of require.Using the synchronization that two-way is orthogonal
Coherent demodulation circuit realiration phase sensitive detection, need not so consider that the phase place of coherent wave whether can inspection with input measured signal homophase
Survey, but the relevant wave phase of two-way must strictly meet 90 ° of phase contrasts, have and certain realize difficulty.
Utility model content
For above-mentioned deficiency of the prior art, technical problem to be solved in the utility model is to provide a kind of locking
Amplifier, allows phase-sensitive detector accurately to adjust coherent wave and signal homophase by Continuous phase shifting, correct so as to measure
Signal magnitude.
In order to solve above-mentioned technical problem, the utility model proposes a kind of lock-in amplifier, including first resistor partial pressure
Network, second resistance potential-divider network, adder, band filter, phase-sensitive detector, low pass filter, the phase shifter and sampling with
Display circuit, the outfan of the outfan and second resistance potential-divider network of the first resistor potential-divider network with the adder
Input connection, the outfan of the adder is connected with the input of the band filter, the band filter
Outfan is connected with the input of the phase-sensitive detector, and the outfan of the phase-sensitive detector is defeated with the low pass filter
Enter end connection, the outfan of the low pass filter is connected with display circuit with the sampling, and interference signal is electric by first
Resistance potential-divider network is entered in lock-in amplifier, is divided into two-way, leads up to second resistance potential-divider network after reference signal input
Into, entering the phase shifter in addition all the way, the outfan of the phase shifter is connected with the phase-sensitive detector.This utility model
Lock-in amplifier preferably realize the detection of small-signal amplitude under strong noise background, mainly for Detection of Weak Signals side
Phase sensitive detection technology in method studied, and is superimposed, is decayed, filtering, examining with sinusoidal interference signal after amplifying to noise source
Ripple, last AD sampling processings simultaneously show, constitutes the locking amplification system of complete set.
In implementing of the present utility model one, between the low pass filter and sampling and display circuit, direct current is additionally provided with
Amplifier.
Further, alternative current amplifier is additionally provided between the adder and the band filter.
In an embodiment of the present utility model, it is additionally provided between the phase shifter and the phase-sensitive detector and compares
Device.
Further, the phase shifter include the first operational amplifier, resistance R1, resistance R2, resistance R3 and electric capacity C1,
The negative-phase input of one operational amplifier is connected with resistance R1, and the normal phase input end of the first operational amplifier is connect by resistance R2
Ground, the positive and negative power end of the first operational amplifier connect+12V, -12V voltage respectively, and the other end of resistance R1 passes through electric capacity C1
It is connected with the normal phase input end of the first operational amplifier, the negative-phase input and electricity of one end of resistance R3 and the first operational amplifier
Connecting node connection between resistance R1, the other end of resistance R3 are connected with the outfan of the first operational amplifier, wherein resistance R2
For adjustable resistance.
Preferably, the low pass filter includes the second operational amplifier, resistance R4, resistance R5, electric capacity C2 and electric capacity C3,
The negative-phase input of second operational amplifier is connected with resistance R4 by electric capacity C2, the positive input of the second operational amplifier
End is grounded by electric capacity C3, the outfan and electric capacity C2 of the negative-phase input of the second operational amplifier and the second operational amplifier it
Between connecting node connection, the normal phase input end of the second operational amplifier is also connected with the resistance R4 by resistance R5.
Implement this utility model, have the advantages that：
Lock-in amplifier of the present utility model is the lock-in amplifier based on phase sensitive detection (PSD) and analog device, is used for
By resistance decrement network and adder, μ V level signals under detection high-noise environment, this utility model realize that very noisy interference is treated
The simulation of micrometer weak signal, small-signal are amplified into band filter by alternative current amplifier, and filter output signal is defeated
Enter the phase-sensitive detector of rear class, phase-sensitive detector is the switch multiplier constructed by analog switch, coherent wave via the phase shifter with
Signal multiplication, output signal is low-pass filtered to obtain DC component, then single-chip microcomputer process is sent into after direct current amplifier, calculates
Afterwards result is included in sampling with display circuit, Jing tests, this utility model can measure signal virtual value exactly, meeting will
Ask.
Description of the drawings
Fig. 1 is the structured flowchart of the lock-in amplifier that this utility model is provided.
Fig. 2 is the fundamental block diagram of the phase-sensitive detector of the lock-in amplifier that this utility model is provided.
Fig. 3 is the circuit diagram of the phase shifter of the lock-in amplifier that this utility model is provided.
Fig. 4 is the circuit diagram of the low pass filter of the lock-in amplifier that this utility model is provided.
Specific embodiment
Below in conjunction with the accompanying drawing in this utility model embodiment, the technical scheme in this utility model embodiment is carried out
Clearly and completely describe, it is clear that described embodiment is only this utility model a part of embodiment, rather than whole
Embodiment.Based on the embodiment in this utility model, those of ordinary skill in the art are not under the premise of creative work is made
The every other embodiment for being obtained, belongs to the scope of this utility model protection.
Referring to Fig. 1, it is the structured flowchart of the lock-in amplifier that this utility model is provided.
The lock-in amplifier includes：First resistor potential-divider network, second resistance potential-divider network, adder, band filter,
Phase-sensitive detector, low pass filter, phase shifter and sampling and display circuit, the outfan of the first resistor potential-divider network and the
The outfan of two resistance pressure-dividing networks is connected with the input of the adder, the outfan of the adder and the band logical
The input connection of wave filter, the outfan of the band filter are connected with the input of the phase-sensitive detector, the phase
The outfan of quick cymoscope is connected with the input of the low pass filter, the outfan of the low pass filter and the sampling
It is connected with display circuit, interference signal is entered in lock-in amplifier by first resistor potential-divider network, reference signal input
After be divided into two-way, lead up to second resistance potential-divider network entrance, in addition all the way enter the phase shifter, the phase shifter it is defeated
Go out end to be connected with the phase-sensitive detector.
Specifically, direct current amplifier is additionally provided between the low pass filter and sampling and display circuit, in order that defeated
It is most suitable scope to enter voltage, and the output voltage range for arranging direct current amplifier is 2～3V.The adder is filtered with the band logical
Alternative current amplifier is additionally provided between ripple device；Comparator is additionally provided between the phase shifter and the phase-sensitive detector.Addition
Device realizes that by the alternative current amplifier first order, when needing to do addition with noise, negative terminal input is earth-free, is changed to connect noise, the
The amplification of one-level is 30 times.Second level amplification realizes stepping for 20,200 or 2000 times by controller amplification, with
The small-signal of correspondence difference voltage level.
Phase-sensitive detector of the present utility model adopts switching regulator multiplier, phase-sensitive detector（PSD）Essence be exactly in fact
Detection is carried out to the phase place between two signals, when two signals are with frequency homophase, at this moment phase-sensitive detector is whole equivalent to all-wave
Stream, the output of detection are maximum, and detection also can be carried out in opposite in phase, and circuit is slightly different, and adopt anti-phase in this utility model,
Fundamental block diagrams of the Fig. 2 for phase-sensitive detector.
As shown in figure 3, the phase shifter of the present utility model include the first operational amplifier, resistance R1, resistance R2, resistance R3 and
Electric capacity C1, the negative-phase input of the first operational amplifier are connected with resistance R1, and the normal phase input end of the first operational amplifier passes through
Resistance R2 is grounded, and the positive and negative power end of the first operational amplifier connects+12V, -12V voltage respectively, and the other end of resistance R1 leads to
The normal phase input end that electric capacity C1 is crossed with the first operational amplifier is connected, and one end of resistance R3 is defeated with the negative of the first operational amplifier
Enter the connecting node connection between end and resistance R1, the other end of resistance R3 is connected with the outfan of the first operational amplifier, its
Middle resistance R2 is adjustable resistance.
The core of phase shifter constitutes difference output by resistance capacitance, can calculate its transmission function and be：
Observation amplitude-frequency characteristic, to its delivery, it is known that：
Wherein,
It can be seen that, this utility model adopt phase shifter there is simple structure, without additional gain, good stability the characteristics of, and
0 to 180 ° of phase shifts can be realized.
As shown in figure 4, low pass filter of the present utility model includes the second operational amplifier, resistance R4, resistance R5, electric capacity
C2 and electric capacity C3, the negative-phase input of second operational amplifier are connected with resistance R4 by electric capacity C2, the second operation amplifier
The normal phase input end of device is grounded by electric capacity C3, the output of the negative-phase input of the second operational amplifier and the second operational amplifier
Connecting node connection between end and electric capacity C2, the normal phase input end of the second operational amplifier also pass through resistance R5 and the resistance
R4 connects.
Using lock-in amplifier of the present utility model, point two-way after the input of reference signal Signal, entering signal is logical all the way
Road, send reference channel all the way.Signal Jing second resistances potential-divider network decay in signalling channel obtains small-signal to be measured, send
Adder is superimposed with interference signal.Interference signal Noise has been superimposed the micro- of interference through isostructural first resistor potential-divider network
Weak signal send phase-sensitive detector to process Jing after band-pass filter.Reference signal Signal first passes through phase shift in reference channel
Device phase shift so that consistent with the small-signal phase place at signalling channel end, triggered comparator are generated and drive square wave to examine into phase sensitivity
The process of ripple device.Phase-sensitive detector realizes detection using analog switch, and output signal is low-pass filtered and direct current amplifier is obtained directly
Flow component.DC voltage is carried out calculating, is processed by single-chip microcomputer, obtain correspondence small-signal virtual value, and including
On screen.
Lock-in amplifier of the present utility model is the lock-in amplifier based on phase sensitive detection (PSD) and analog device, is used for
μ V level signals under detection high-noise environment.By resistance decrement network and adder, this utility model realizes that very noisy interference is treated
The simulation of micrometer weak signal, small-signal are amplified into band filter by alternative current amplifier, and filter output signal is defeated
Enter the phase-sensitive detector of rear class, phase-sensitive detector is the switch multiplier constructed by analog switch, coherent wave via the phase shifter with
Signal multiplication, output signal is low-pass filtered to obtain DC component, then single-chip microcomputer process is sent into after direct current amplifier, calculates
Afterwards result is included in sampling with display circuit, Jing tests, this utility model can measure signal virtual value exactly, meeting will
Ask.Lock-in amplifier of the present utility model, preferably realizes the detection of small-signal amplitude under strong noise background, mainly for
Phase sensitive detection technology in method for detecting weak signals is studied, and is folded with sinusoidal interference signal after amplifying to noise source
Plus, decay, filtering, detection, last AD sampling processings simultaneously show, constitute the locking amplification system of complete set.
The above is preferred implementation of the present utility model, it is noted that for the ordinary skill of the art
For personnel, on the premise of without departing from this utility model principle, some improvement and deformation can also be made, these improve and become
Shape is also considered as protection domain of the present utility model.
Claims (6)
1. a kind of lock-in amplifier, it is characterised in that including first resistor potential-divider network, second resistance potential-divider network, adder,
Band filter, phase-sensitive detector, low pass filter, phase shifter and sampling and display circuit, the first resistor potential-divider network
Outfan and the outfan of second resistance potential-divider network be connected with the input of the adder, the output of the adder
End is connected with the input of the band filter, the input of the outfan of the band filter and the phase-sensitive detector
Connection, the outfan of the phase-sensitive detector are connected with the input of the low pass filter, the output of the low pass filter
End is connected with display circuit with the sampling, and interference signal is entered in lock-in amplifier by first resistor potential-divider network,
It is divided into two-way after reference signal input, leads up to the entrance of second resistance potential-divider network, enters the phase shifter, institute in addition all the way
The outfan for stating the phase shifter is connected with the phase-sensitive detector.
2. lock-in amplifier as claimed in claim 1, it is characterised in that the low pass filter and sampling and display circuit it
Between be additionally provided with direct current amplifier.
3. lock-in amplifier as claimed in claim 1, it is characterised in that between the adder and the band filter also
It is provided with alternative current amplifier.
4. lock-in amplifier as claimed in claim 1, it is characterised in that between the phase shifter and the phase-sensitive detector also
It is provided with comparator.
5. lock-in amplifier as claimed in claim 1, it is characterised in that the phase shifter includes the first operational amplifier, electricity
Resistance R1, resistance R2, resistance R3 and electric capacity C1, the negative-phase input of the first operational amplifier are connected with resistance R1, and the first computing is put
The normal phase input end of big device is grounded by resistance R2, and it is electric that the positive and negative power end of the first operational amplifier connects+12V, -12V respectively
Pressure, the other end of resistance R1 is connected with the normal phase input end of the first operational amplifier by electric capacity C1, one end of resistance R3 and the
Connecting node connection between the negative-phase input and resistance R1 of one operational amplifier, the other end of resistance R3 are put with the first computing
The outfan connection of big device, wherein resistance R2 is adjustable resistance.
6. lock-in amplifier as claimed in claim 1, it is characterised in that the low pass filter includes the second operation amplifier
Device, resistance R4, resistance R5, electric capacity C2 and electric capacity C3, the negative-phase input of second operational amplifier is by electric capacity C2 and electricity
Resistance R4 connections, the normal phase input end of the second operational amplifier are grounded by electric capacity C3, the negative-phase input of the second operational amplifier
And the connecting node between the outfan and electric capacity C2 of the second operational amplifier is connected, the normal phase input end of the second operational amplifier
Also it is connected with the resistance R4 by resistance R5.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201621164329.2U CN206099914U (en) | 2016-11-01 | 2016-11-01 | Lock -in amplifier |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201621164329.2U CN206099914U (en) | 2016-11-01 | 2016-11-01 | Lock -in amplifier |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN206099914U true CN206099914U (en) | 2017-04-12 |
Family
ID=58486091
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201621164329.2U Expired - Fee Related CN206099914U (en) | 2016-11-01 | 2016-11-01 | Lock -in amplifier |
Country Status (1)
| Country | Link |
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| CN (1) | CN206099914U (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108288956A (en) * | 2017-12-29 | 2018-07-17 | 河南北瑞电子科技有限公司 | A kind of digital Lock-in Amplifier based on DSP |
| CN109166387A (en) * | 2018-05-07 | 2019-01-08 | 南京信息工程大学 | A kind of uV grade Detection of Weak Signals teaching box based on frequency-region signal narrowband |
| CN109506078A (en) * | 2018-12-21 | 2019-03-22 | 苏州经贸职业技术学院 | A kind of robot for the detection of PCCP pipeline steel wire fracture of wire |
| CN109854861A (en) * | 2018-12-21 | 2019-06-07 | 苏州经贸职业技术学院 | A kind of PCCP pipe fault detection system |
| CN110530547A (en) * | 2019-09-26 | 2019-12-03 | 中国科学院长春光学精密机械与物理研究所 | A kind of micro- K magnitude temperature measuring device based on Wheatstone bridge and lock-in amplifier |
-
2016
- 2016-11-01 CN CN201621164329.2U patent/CN206099914U/en not_active Expired - Fee Related
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108288956A (en) * | 2017-12-29 | 2018-07-17 | 河南北瑞电子科技有限公司 | A kind of digital Lock-in Amplifier based on DSP |
| CN109166387A (en) * | 2018-05-07 | 2019-01-08 | 南京信息工程大学 | A kind of uV grade Detection of Weak Signals teaching box based on frequency-region signal narrowband |
| CN109166387B (en) * | 2018-05-07 | 2024-01-30 | 南京信息工程大学 | uV level weak signal detection teaching box based on frequency domain signal narrowband |
| CN109506078A (en) * | 2018-12-21 | 2019-03-22 | 苏州经贸职业技术学院 | A kind of robot for the detection of PCCP pipeline steel wire fracture of wire |
| CN109854861A (en) * | 2018-12-21 | 2019-06-07 | 苏州经贸职业技术学院 | A kind of PCCP pipe fault detection system |
| CN109506078B (en) * | 2018-12-21 | 2022-03-25 | 苏州经贸职业技术学院 | Robot for detecting broken steel wire of PCCP pipeline |
| CN110530547A (en) * | 2019-09-26 | 2019-12-03 | 中国科学院长春光学精密机械与物理研究所 | A kind of micro- K magnitude temperature measuring device based on Wheatstone bridge and lock-in amplifier |
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Legal Events
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| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20170412 Termination date: 20171101 |
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| CF01 | Termination of patent right due to non-payment of annual fee |