CN110530547A - A kind of micro- K magnitude temperature measuring device based on Wheatstone bridge and lock-in amplifier - Google Patents
A kind of micro- K magnitude temperature measuring device based on Wheatstone bridge and lock-in amplifier Download PDFInfo
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- CN110530547A CN110530547A CN201910918601.3A CN201910918601A CN110530547A CN 110530547 A CN110530547 A CN 110530547A CN 201910918601 A CN201910918601 A CN 201910918601A CN 110530547 A CN110530547 A CN 110530547A
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- wheatstone bridge
- amplifier
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- lock
- resistance
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K7/00—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements
- G01K7/16—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements
- G01K7/18—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements the element being a linear resistance, e.g. platinum resistance thermometer
- G01K7/20—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements the element being a linear resistance, e.g. platinum resistance thermometer in a specially-adapted circuit, e.g. bridge circuit
Abstract
A kind of micro- K magnitude temperature measuring device based on Wheatstone bridge and lock-in amplifier is related to high-precision signal fields of measurement, which includes: Wheatstone bridge road, locking phase amplification module and analog-to-digital conversion module；Wheatstone bridge road Wheatstone bridge includes three reference resistances, a temperature detecting resistance and two emitter followers；One end of first emitter follower is connect with one end of the temperature detecting resistance, and the other end is connect with locking phase amplification acquisition module；One end of second emitter follower is connect with the other end of the temperature detecting resistance, the other end is connect with one end of neighboring reference circuit, the other end of the neighboring reference resistance is connect with locking phase amplification acquisition module, and the locking phase amplification acquisition module is connected with analog-to-digital conversion module.The present invention combines Wheatstone bridge and lock-in amplifier, realizes 10‑6Magnitude temperature acquisition.Emitter follower is introduced at temperature detecting resistance both ends simultaneously, the selection of lock-in amplifier frequency is in 5kHz between 15kHz, avoiding the influence of other resistance and parasitic capacitance to measurement accuracy.
Description
Technical field
The present invention relates to high-precision signal field of measuring technique, and in particular to one kind is amplified based on Wheatstone bridge and locking phase
Micro- K magnitude temperature measuring device of device.
Background technique
In fields such as gravity experiment, gravity measurement and earth tide nighttide detections, since the signal to be detected is extremely micro-
It is weak and have quite high requirement to experimental result precision, it is necessary to try to overcome the influence of various external interference factors.Temperature becomes
Change is one of important factor in order therein.To guarantee isoperibol, high-precision temperature sensor is needed just to be able to achieve high-precision
The temperature of degree controls.
The measurement of temperature at present is the most frequently used by the variation of the reacting condition temperature of resistance value usually using thermistor
Be PT1000 platinum resistance.Measurement of the high-precision temperature measurement really to the faint variation of resistance, the original substantially of resistance measurement
Reason is to give an excitation current source, measures the resistance according to the voltage that the two-terminal element two-end-point obtains and electric current is hindered
The size of effect.It is voltammetry and Wheatstone bridge method based on the common measurement method of this principle.Wheatstone bridge is by four
The bridge circuit of resistance composition, this four resistance are called the bridge arm of electric bridge respectively, and Wheatstone bridge is surveyed using the variation of resistance
The variation for measuring physical quantity, will be measured be compared with known quantity when measurement and obtain measurement result, and usual three resistance values are
Know, the 4th resistance can be acquired.
Then the variation of bridge output voltage, which finally requires to be acquired, to be handled, the acquisition precision of data also will affect most
The whole precision used, the factor for influencing acquisition precision mainly have circuit devcie bring voltage noise, current noise, surrounding ring
Border bring electromagnetic interference, power-supply fluctuation, quantizing noise of digital collection etc., these can all influence the acquisition of bridge output voltage
Precision.It is very faint in the signal that bridge both ends generate for measurement the milliohm even resistance variations of micro-ohm magnitude, it is easy by noise
Interference, noise and interference cannot be eliminated by only carrying out signal amplification, and use lock-in amplifier based on coherent detection technology,
It is identical with frequency of carrier signal using reference signal, with the incoherent feature of noise, useful signal, Ke Yiyou are extracted from noise
Effect overcomes external interference to obtain more stable output voltage, is a kind of effective method for detecting weak signals.
Summary of the invention
In order to solve the problems in the existing technology, the present invention provides one kind is amplified based on Wheatstone bridge and locking phase
It is dry vulnerable to transfer wire resistance, ambient enviroment electromagnetism to solve low-frequency range small-signal for micro- K magnitude temperature measuring device of device
It disturbs, the problem of circuit chip noise and parasitic capacitance etc. influence.
The technical proposal for solving the technical problem of the invention is as follows:
A kind of micro- K magnitude temperature measuring device based on Wheatstone bridge and lock-in amplifier, which includes: favour stone
Bridge, locking phase amplification module and analog-to-digital conversion module；Wheatstone bridge road Wheatstone bridge includes three reference resistances, one
Temperature detecting resistance and two emitter followers；One end of first emitter follower is connect with one end of the temperature detecting resistance, the other end and the lock
Mutually amplification acquisition module connection；One end of second emitter follower is connect with the other end of the temperature detecting resistance, the other end and adjacent ginseng
One end connection of circuit is examined, the other end of the neighboring reference resistance is connect with locking phase amplification acquisition module；The locking phase
Amplifying acquisition module includes preamplifier, main amplifier, bandpass filtering, demodulator, low-pass filter, trigger, phase shifter
And sine wave；The preamplifier, main amplifier, bandpass filtering, demodulator and low-pass filter are sequentially connected, and are finally entered
Analog-to-digital conversion module；The trigger, phase shifter and sine wave are sequentially connected；The sine wave is connect with the demodulator.
Preferably, the digit of the analog-to-digital conversion module is 24.
Preferably, the frequency range of the bandpass filter is 5kHZ-15kHZ.
Preferably, the side for replacing temperature detecting resistance to carry out circuit zero point and gain calibration using measuring resistance in circuit is proposed
Method, the biased error of compensation circuit.
Preferably, the emitter follower is made of high input impedance low output impedance operational amplifier OP07, operational amplifier
Output and operational amplifier reverse side interconnect, operational amplifier input be operational amplifier in-phase end, operational amplifier output
For operational amplifier output terminal.The beneficial effects of the present invention are: the present invention combines Wheatstone bridge and lock-in amplifier, it is real
Existing 10-6Magnitude temperature acquisition.The design and frequency selection for optimizing Wheatstone bridge simultaneously, introduce emitter following at temperature detecting resistance both ends
Device, lock-in amplifier frequency selection 5kHz between 15kHz, avoid conductor resistance, contact resistance and parasitic capacitance to measurement
The influence of precision.Conventional ring oscillator is replaced using switching regulator ring oscillator, circuit work when ring oscillator by
To the control of pulse signal, the only work when needing to run, such design can significantly reduce additional power consumption.Directly
The rising edge number of ring oscillator when by counter calculating pulse signal, which is stored by register and is exported,
Both now corresponding digital signal can have been obtained.
Detailed description of the invention
A kind of micro- K magnitude temperature measuring device structural representation based on Wheatstone bridge and lock-in amplifier of Fig. 1 present invention
Figure.
A kind of Fig. 2 micro- K magnitude temperature measuring device based on Wheatstone bridge and lock-in amplifier of the present invention 1mHz extremely
5Hz frequency range temperature Measurement Resolution power spectrum curve.
Fig. 3 present invention is a kind of based on micro- K magnitude temperature measuring device of Wheatstone bridge and lock-in amplifier actual measurement 1000
Second time domain data.Specific embodiment
Specific embodiment
The present invention is described in further details with reference to the accompanying drawings and examples.
In order to realize 10-6Magnitude temperature acquisition, this patent combine Wheatstone bridge and lock-in amplifier, optimize simultaneously
The design and frequency of Wheatstone bridge select, and avoid the influence of conductor resistance, contact resistance and parasitic capacitance to measurement accuracy.Figure
1 is measuring device principle assumption diagram.
As shown in Figure 1, a kind of micro- K magnitude temperature measuring device based on Wheatstone bridge and lock-in amplifier, the device
It include: Wheatstone bridge road and locking phase amplification acquisition module；Wheatstone bridge road Wheatstone bridge include three reference resistance R1,
R2 and R3, a temperature detecting resistance RT, two emitter follower U1And U2；Described R1, R2, R3 and RTArranged clockwise.First emitter follower U1
One end and the temperature detecting resistance RTOne end connection, the other end and the locking phase are amplified acquisition module and are connect；Second emitter follower U2
One end and the temperature detecting resistance RTThe other end connection, the other end is connect with one end of neighboring reference circuit R3, described adjacent
The other end of reference resistance R3 is connect with locking phase amplification acquisition module；The locking phase amplification acquisition module includes preposition amplification
Device, main amplifier, bandpass filtering, demodulator, low-pass filter, digital analog converter, trigger, phase shifter and sine wave；It is described
Preamplifier, main amplifier, bandpass filtering, demodulator, low-pass filter and digital analog converter are sequentially connected；The triggering
Device, phase shifter and sine wave are sequentially connected；The sine wave is connect with the demodulator.
In the present embodiment, reference resistance R1, R2 and R3 size and temperature detecting resistance RTIt is identical, it is first used in circuit using preceding
Measuring resistance replaces temperature detecting resistance RTCircuit zero point is demarcated, the biased error of compensation circuit.U1And U2Guarantee RTTo locking phase
Amplifying acquisition module both ends has high input impedance, avoids conductor resistance to temperature detecting resistance RTThe influence of variation.Wheatstone bridge
Output enter preamplifier in a differential manner and prevent big, preventing big purpose is to seek Wheatstone bridge both end voltage
Difference eliminates common-mode error, obtains voltage signal all the way and enter main amplifier carrying out main amplification, and main amplifier output enters band logical and filters
Wave device filters out the noise other than frequency of carrier signal, bandpass filter output and the triggered device of reference source, phase shifter and sine wave
Enter in multiplication demodulator after phase modulation, obtains direct current and two frequency-doubled signals enter low-pass filter, last low-pass filter output
DC component collect voltage signal to be measured through analog-digital converter.Above-mentioned amplifier is required to selection low noise sound chip, drop
Low chip voltage noise, influence of the current noise to signal, modulus conversion chip select the chip more than digit with reduction amount as far as possible
Change noise (24 current highests), the signal after analog-to-digital conversion is further processed through wave digital lowpass filter algorithm to reduce signal
Noise is general to select average and FIR algorithm.In the apparatus, the frequency of signal should select as far as possible in low frequency, to avoid in circuit
Influence of the parasitic capacitance to measurement accuracy, but the bandpass filter of the too low lock-in amplifier of frequency is insufficient in low-frequency range decaying, no
Conducive to noise filtering, signal frequency selection is comprehensively considered in 5kHz between 15kHz.
Fig. 2 is temperature measuring device of the present invention in 1mHz to 5Hz frequency range temperature Measurement Resolution power spectrum curve.It is wherein horizontal
Coordinate is frequency, unit Hz；Ordinate is temperature, unit K/Hz1/2；The curve reflects that apparatus of the present invention are to temperature at each frequency
The resolution ratio of measurement is spent, it can be achieved that 3.9uK@1Hz.
Fig. 3 temperature measuring device of the present invention is surveying 1000 seconds time domain datas.Abscissa is time, unit second；Ordinate
For the voltage value of analog-digital converter acquisition, unit V；100Hz is the data under original sampling frequency, and 10Hz is by low-pass filtering
Down-sampled data afterwards, for analyzing the power spectrum of 1mHz to 5Hz frequency range temperature resolution.
Claims (5)
1. a kind of micro- K magnitude temperature measuring device based on Wheatstone bridge and lock-in amplifier, which is characterized in that the device packet
It includes: Wheatstone bridge road, locking phase amplification module and analog-to-digital conversion module；Wheatstone bridge road Wheatstone bridge includes three references
Resistance, a temperature detecting resistance and two emitter followers；One end of first emitter follower is connect with one end of the temperature detecting resistance, the other end
It is connect with locking phase amplification acquisition module；One end of second emitter follower is connect with the other end of the temperature detecting resistance, the other end
It is connect with one end of neighboring reference circuit, the other end of the neighboring reference resistance is connect with locking phase amplification acquisition module；
The locking phase amplification acquisition module includes preamplifier, main amplifier, bandpass filtering, demodulator, low-pass filter, triggering
Device, phase shifter and sine wave；The preamplifier, main amplifier, bandpass filtering, demodulator and low-pass filter successively connect
It connects, finally enters analog-to-digital conversion module；The trigger, phase shifter and sine wave are sequentially connected；The sine wave and the solution
Adjust device connection.
2. a kind of micro- K magnitude temperature measuring device based on Wheatstone bridge and lock-in amplifier according to claim 1,
It is characterized in that, the digit of the analog-to-digital conversion module is 24.
3. a kind of micro- K magnitude temperature measuring device based on Wheatstone bridge and lock-in amplifier according to claim 1,
It is characterized in that, the frequency range of the bandpass filter is 5kHZ-15kHZ.
4. a kind of micro- K magnitude temperature measuring device based on Wheatstone bridge and lock-in amplifier according to claim 1,
It is characterized in that, propose the method for replacing temperature detecting resistance to carry out circuit zero point and gain calibration using measuring resistance in circuit,
The biased error of compensation circuit.
5. a kind of micro- K magnitude temperature measuring device based on Wheatstone bridge and lock-in amplifier according to claim 1,
It is characterized in that, the emitter follower is made of high input impedance low output impedance operational amplifier OP07, operational amplifier it is defeated
It is interconnected out with operational amplifier reverse side, input of the in-phase end of operational amplifier as emitter follower, the output of operational amplifier
Hold the output as emitter follower.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201910918601.3A CN110530547A (en) | 2019-09-26 | 2019-09-26 | A kind of micro- K magnitude temperature measuring device based on Wheatstone bridge and lock-in amplifier |
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| CN201910918601.3A CN110530547A (en) | 2019-09-26 | 2019-09-26 | A kind of micro- K magnitude temperature measuring device based on Wheatstone bridge and lock-in amplifier |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112857406A (en) * | 2021-01-08 | 2021-05-28 | 重庆开谨科技有限公司 | High-voltage excited Wheatstone bridge measuring method |
| CN112910885A (en) * | 2021-01-29 | 2021-06-04 | 湖北民族大学 | Secure communication system and method based on Wheatstone bridge balance method |
| CN115372408A (en) * | 2022-08-08 | 2022-11-22 | 东南大学 | Automatic 3 omega test system and method based on bridge and data acquisition card |
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| CN108507695A (en) * | 2017-02-27 | 2018-09-07 | 北京自动化控制设备研究所 | A kind of atomic air chamber temperature checking method based on locking phase amplification |
| CN208187581U (en) * | 2018-02-06 | 2018-12-04 | 天津市朝华电子技术有限公司 | A kind of high-resolution hydrocode thick film circuit |
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| CN206099914U (en) * | 2016-11-01 | 2017-04-12 | 武汉科技大学 | Lock -in amplifier |
| CN108507695A (en) * | 2017-02-27 | 2018-09-07 | 北京自动化控制设备研究所 | A kind of atomic air chamber temperature checking method based on locking phase amplification |
| CN208187581U (en) * | 2018-02-06 | 2018-12-04 | 天津市朝华电子技术有限公司 | A kind of high-resolution hydrocode thick film circuit |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112857406A (en) * | 2021-01-08 | 2021-05-28 | 重庆开谨科技有限公司 | High-voltage excited Wheatstone bridge measuring method |
| CN112857406B (en) * | 2021-01-08 | 2023-05-23 | 重庆开谨科技有限公司 | High-voltage excitation Wheatstone bridge measurement method |
| CN112910885A (en) * | 2021-01-29 | 2021-06-04 | 湖北民族大学 | Secure communication system and method based on Wheatstone bridge balance method |
| CN115372408A (en) * | 2022-08-08 | 2022-11-22 | 东南大学 | Automatic 3 omega test system and method based on bridge and data acquisition card |
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