CN106817100A - A kind of amplifying circuit for tiny signal - Google Patents
A kind of amplifying circuit for tiny signal Download PDFInfo
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- CN106817100A CN106817100A CN201510867650.0A CN201510867650A CN106817100A CN 106817100 A CN106817100 A CN 106817100A CN 201510867650 A CN201510867650 A CN 201510867650A CN 106817100 A CN106817100 A CN 106817100A
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- amplifying circuit
- signal
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
- H03F3/68—Combinations of amplifiers, e.g. multi-channel amplifiers for stereophonics
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Abstract
A kind of amplifying circuit for tiny signal, the three amplifier measuring and amplifying circuits with automatic offset compensation using LM725CN, as the pre-amplifier of this amplifying circuit, the instrument amplifier of this form, its input impedance is about 30~5000MQ, common-mode rejection ratio (CMR) Rdb=74~110dB, input offset voltage Vas=0.2mV, offset voltage temperature drift r=0.25~10μV/℃.Amplifying circuit for tiny signal meets the requirement of voltage amplification, it is to avoid distorted signals, and high frequency, low frequency and 50Hz civil powers interference, the circuit is widely portable in the signal transacting of instrument.
Description
Technical field
The present invention relates to a kind of amplifying circuit for tiny signal, it is adaptable to electronic applications.
Background technology
Hot-probing element is the core of hot-probing sensor, and this class component is using metal oxide as material.Due to production and the influence of manufacturing environment, cause material property very unstable, so that the response homogeneity difference of the heat sensor for manufacturing is very big.At present using from substantial amounts of provided as one homogeneous element, pick out the method for the consistent product of response performance to solve the problems, such as response homogeneity difference.Therefore screening just turns into vital work, and it is the key for completing performance test to develop a high-precision test system.The test system is radiated at hot-probing element surface by a laser and through optical system generation ζ≤0.1mm hot spots, detector has small signal output, fundamental signal is selected by amplifier, and it is amplified to the acceptable range of signal of A/D change-over panels, make a gift to someone computer, computer is recorded to the response data of the point and carries out Treatment Analysis.
The content of the invention
The present invention proposes a kind of amplifying circuit for tiny signal, amplifying circuit for tiny signal meets the requirement of voltage amplification, it is to avoid distorted signals, and high frequency, low frequency and 50Hz civil powers interference, the circuit is widely portable in the signal transacting of instrument.
The technical solution adopted in the present invention is：The amplifying circuit uses three amplifier measuring and amplifying circuits of the LM725CN with automatic offset compensation, and used as the pre-amplifier of this amplifying circuit, the instrument amplifier of this form, its input impedance is about 30~5000MQ, common-mode rejection ratio (CMR) Rdb=74~110dB, input offset voltage Vas=0.2mV, offset voltage temperature drift r=0.25~10μV/℃.Change R1 resistances and can obtain different KUD values.The input of three amplifier two is homophase input, and more than 10M Ω are typically lived in input impedance.The features such as three amplifier measuring amplifiers have high cmrr, high input impedance, adjustable gain.A compensation network is increased in three amplifiers.Amplifier A4 and resistance R, electric capacity C constitute an integrator, its effect be by the dc component of amplifier A3 output ends it is integrated, it is anti-phase after feed back to its in-phase input end, subtracted from input signal, so as to eliminate the influence of offset voltage.
In order to reduce the high-frequency interferencing signal beyond signal modulation frequency, add this low pass filter and filter it.LPF is made up of double operational integrated circuit OP2177.OP2177 has the features such as high accuracy, low biasing, low-power consumption, and two discharge circuits of Embedded can flexibly constitute all kinds of amplifications and filter circuit.
The effect of main amplifying circuit is that the signal of sensor is amplified into the receptible scope of A/D converter institute, to avoid distorted signals, main amplifying circuit is just divided into front and back stages, respectively the input/output terminal of connection and 50Hz trappers, and each 100 times of gain amplifier is provided.Because sensor output signal only has 1~100 μ VppAnd A/D conversion signals 0~10V of requirement, therefore the multiplication factor of whole signal amplification circuit needs 100000 times or so.About 10 times or so of the multiplication factor of pre-amplification circuit, therefore main amplifying circuit is designed as two-stage amplification, every grade of 100 times or so of multiplication factor.
The amplifying circuit is using the double T feedbacks frequency-selective amplifiers of integrated transporting discharging, Hz noise is the main interference of signal, although pre-amplification circuit has stronger inhibitory action to common mode disturbances, there is part Hz noise to be and circuit is entered in differential mode mode, so having to filter out.
The beneficial effects of the invention are as follows：Amplifying circuit for tiny signal meets the requirement of voltage amplification, it is to avoid distorted signals, and high frequency, low frequency and 50Hz civil powers interference, the circuit is widely portable in the signal transacting of instrument.
Brief description of the drawings
The present invention is further described with reference to the accompanying drawings and examples.
Fig. 1 is three amplifier measuring amplifier circuit diagrams of the automatic offset compensation of band of the invention.
Fig. 2 is low-pass filter circuit figure of the invention.
Specific embodiment
The invention will be further described with reference to the accompanying drawings and examples.
As Fig. 1, amplifying circuit use three amplifier measuring and amplifying circuits of the LM725CN with automatic offset compensation, used as the pre-amplifier of this amplifying circuit, the instrument amplifier of this form, its input impedance is about 30~5000MQ, common-mode rejection ratio (CMR) Rdb=74~110dB, input offset voltage Vas=0.2mV, offset voltage temperature drift r=0.25~10μV/℃.Change R1 resistances and can obtain different KUD values.The input of three amplifier two is homophase input, and more than 10M Ω are typically lived in input impedance.The features such as three amplifier measuring amplifiers have high cmrr, high input impedance, adjustable gain.A compensation network is increased in three amplifiers.Amplifier A4 and resistance R, electric capacity C constitute an integrator, its effect be by the dc component of amplifier A3 output ends it is integrated, it is anti-phase after feed back to its in-phase input end, subtracted from input signal, so as to eliminate the influence of offset voltage.
Such as Fig. 2, in order to reduce the high-frequency interferencing signal beyond signal modulation frequency, add this low pass filter and filter it.LPF is made up of double operational integrated circuit OP2177.OP2177 has the features such as high accuracy, low biasing, low-power consumption, and two discharge circuits of Embedded can flexibly constitute all kinds of amplifications and filter circuit.
The effect of main amplifying circuit is that the signal of sensor is amplified into the receptible scope of A/D converter institute, to avoid distorted signals, main amplifying circuit is just divided into front and back stages, respectively the input/output terminal of connection and 50Hz trappers, and each 100 times of gain amplifier is provided.Because sensor output signal only has 1~100 μ VppAnd A/D conversion signals 0~10V of requirement, therefore the multiplication factor of whole signal amplification circuit needs 100000 times or so.About 10 times or so of the multiplication factor of pre-amplification circuit, therefore main amplifying circuit is designed as two-stage amplification, every grade of 100 times or so of multiplication factor.
Using the double T feedbacks frequency-selective amplifiers of integrated transporting discharging, Hz noise is the main interference of signal to amplifying circuit, although pre-amplification circuit has stronger inhibitory action to common mode disturbances, but it is to enter circuit in differential mode mode to have part Hz noise, so having to filter out.
Claims (5)
1. a kind of amplifying circuit for tiny signal, it is characterized in that：The amplifying circuit uses three amplifier measuring and amplifying circuits of the LM725CN with automatic offset compensation, and used as the pre-amplifier of this amplifying circuit, the instrument amplifier of this form, its input impedance is about 30~5000MQ, common-mode rejection ratio (CMR) Rdb=74~110dB, input offset voltage Vas=0.2mV, offset voltage temperature drift r=0.25~10μV/℃。
2. a kind of amplifying circuit for tiny signal according to claim 1, it is characterized in that：The amplifier A4 and resistance R, electric capacity C constitute an integrator, its effect be by the dc component of amplifier A3 output ends it is integrated, it is anti-phase after feed back to its in-phase input end, subtracted from input signal, so as to eliminate the influence of offset voltage.
3. a kind of amplifying circuit for tiny signal according to claim 1, it is characterized in that：In order to reduce the high-frequency interferencing signal beyond signal modulation frequency, add this low pass filter and filter it, LPF is made up of double operational integrated circuit OP2177.
4. a kind of amplifying circuit for tiny signal according to claim 1, it is characterized in that：The effect of the main amplifying circuit is that the signal of sensor is amplified into the receptible scope of A/D converter institute, to avoid distorted signals, main amplifying circuit is just divided into front and back stages, respectively the input/output terminal of connection and 50Hz trappers, and each 100 times of gain amplifier is provided;Because sensor output signal only has 1~100 μ VppAnd A/D conversion signals 0~10V of requirement, therefore the multiplication factor of whole signal amplification circuit needs 100000 times or so.
5. a kind of amplifying circuit for tiny signal according to claim 1, it is characterized in that：The amplifying circuit is using the double T feedbacks frequency-selective amplifiers of integrated transporting discharging, Hz noise is the main interference of signal, although pre-amplification circuit has stronger inhibitory action to common mode disturbances, there is part Hz noise to be and circuit is entered in differential mode mode, so having to filter out.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201510867650.0A CN106817100A (en) | 2015-12-01 | 2015-12-01 | A kind of amplifying circuit for tiny signal |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201510867650.0A CN106817100A (en) | 2015-12-01 | 2015-12-01 | A kind of amplifying circuit for tiny signal |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN106817100A true CN106817100A (en) | 2017-06-09 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201510867650.0A Pending CN106817100A (en) | 2015-12-01 | 2015-12-01 | A kind of amplifying circuit for tiny signal |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN106817100A (en) |
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2015
- 2015-12-01 CN CN201510867650.0A patent/CN106817100A/en active Pending
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Legal Events
| Date | Code | Title | Description |
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| PB01 | Publication | ||
| PB01 | Publication | ||
| WD01 | Invention patent application deemed withdrawn after publication |
Application publication date: 20170609 |
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| WD01 | Invention patent application deemed withdrawn after publication |