CN111077358A - Detection device for micro-current signal - Google Patents
Detection device for micro-current signal Download PDFInfo
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- CN111077358A CN111077358A CN201911326753.0A CN201911326753A CN111077358A CN 111077358 A CN111077358 A CN 111077358A CN 201911326753 A CN201911326753 A CN 201911326753A CN 111077358 A CN111077358 A CN 111077358A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/0092—Arrangements for measuring currents or voltages or for indicating presence or sign thereof measuring current only
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R1/00—Details of instruments or arrangements of the types included in groups G01R5/00 - G01R13/00 and G01R31/00
- G01R1/02—General constructional details
- G01R1/04—Housings; Supporting members; Arrangements of terminals
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R1/00—Details of instruments or arrangements of the types included in groups G01R5/00 - G01R13/00 and G01R31/00
- G01R1/02—General constructional details
- G01R1/18—Screening arrangements against electric or magnetic fields, e.g. against earth's field
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/0046—Arrangements for measuring currents or voltages or for indicating presence or sign thereof characterised by a specific application or detail not covered by any other subgroup of G01R19/00
- G01R19/0061—Measuring currents of particle-beams, currents from electron multipliers, photocurrents, ion currents; Measuring in plasmas
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- Plasma & Fusion (AREA)
- Measurement Of Current Or Voltage (AREA)
Abstract
The embodiment of the invention provides a detection device for micro-current signals, which comprises a micro-current signal acquisition port, a micro-current signal amplification circuit and a shielding shell, wherein: the micro-current signal acquisition port is used for shielding interference noise in the micro-current signal to obtain the micro-current signal after the interference noise is shielded, and the output end of the micro-current signal acquisition port is connected with the micro-current signal amplification circuit; the micro-current signal amplifying circuit is arranged in the shielding shell and used for amplifying the micro-current signal after shielding the interference noise to obtain a target micro-current signal so as to obtain a signal detection result according to the target micro-current signal; and the shielding shell is used for shielding the micro-current signal amplifying circuit from interference signals. The embodiment of the invention has higher detection precision and better anti-interference capability on external interference signals when detecting the micro-current signals.
Description
Technical Field
The invention relates to the technical field of signal detection, in particular to a detection device for micro-current signals.
Background
The micro-current is used as a key in the microscopic field of opening electronic tests, is widely applied in the fields of safety detection, pH value detection and medical detection, and the current explored by the micro-current is from uA and nA to pA and fA or even single electron.
The explosive/drug detection equipment based on FAIMS (non-linear ion mobility spectrometry) technology ionizes detected particles and charged ions at an ionization source, and the ionized and charged ions are enriched at a detection electrode under the action of gas path airflow and a migration electric field, so that a weak current signal is formed, and the current magnitude of the weak current signal is in the pA level.
The traditional micro-current signal detection device has poor signal anti-interference capability, high waveform distortion degree and large volume of a signal acquisition shielding part, so that the space utilization rate of a signal input and output part is low, and the detection precision, the type of a detected object and the false detection alarm rate of an explosive detection instrument are greatly influenced. Therefore, a detection device for micro current signals is needed to solve the above problems.
Disclosure of Invention
In order to solve the problems in the prior art, embodiments of the present invention provide a detection apparatus for a micro-current signal.
The embodiment of the invention provides a detection device for micro-current signals, which comprises a micro-current signal acquisition port, a micro-current signal amplification circuit and a shielding shell, wherein:
the micro-current signal acquisition port is used for shielding interference noise in the micro-current signal to obtain the micro-current signal after the interference noise is shielded, and the output end of the micro-current signal acquisition port is connected with the micro-current signal amplification circuit;
the micro-current signal amplifying circuit is arranged in the shielding shell and used for amplifying the micro-current signal after shielding the interference noise to obtain a target micro-current signal so as to obtain a signal detection result according to the target micro-current signal;
and the shielding shell is used for shielding the micro-current signal amplifying circuit from interference signals.
Further, the micro-current signal amplifying circuit comprises a first amplifying circuit module and a second amplifying circuit module, wherein:
the first amplifying circuit module consists of a first resistor, a second resistor, a third resistor, a fifth resistor, a seventh resistor, a first capacitor, a second capacitor, a third capacitor, a fourth capacitor and a first operational amplifier;
the second amplifying circuit module is composed of a fourth resistor, a sixth resistor, an eighth resistor and a second operational amplifier.
Further, the shield case includes a first shield case and a second shield case, wherein:
the first shielding shell is used for shielding the first amplifying circuit module from interference signals, and the first amplifying circuit module is arranged in the first shielding shell;
the second shielding shell is used for shielding the micro-current signal amplification circuit, and the first amplification circuit module, the second amplification circuit module and the first shielding shell are arranged inside the second shielding shell.
Further, first shielding shell is the metal material, second shielding shell is aluminium system material, wherein, first shielding shell with little current signal amplifier circuit's integrated circuit board PCB ground signal connection, the fixed orifices of integrated circuit board PCB ground signal is fixed to be set up the bottom of second shielding shell, so that second shielding shell connects ground.
Further, a guard ring is disposed in the first amplification circuit module, and the guard ring is obtained by performing guard ring processing on an input end of the first amplification circuit module.
Further, the micro-current signal acquisition port is an MMCX connector.
Further, the interface diameter of the MMCX connector is not more than 5mm, and the impedance is 50 ohms.
The detection device for the micro-current signal provided by the embodiment of the invention has higher detection precision and better anti-interference capability on external interference signals when the micro-current signal is detected.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and those skilled in the art can also obtain other drawings according to the drawings without creative efforts.
FIG. 1 is a schematic structural diagram of a detection apparatus for a micro-current signal according to an embodiment of the present invention;
FIG. 2 is a schematic circuit diagram of a micro-current signal amplifying circuit according to an embodiment of the present invention;
fig. 3 is a schematic diagram of a first shielding shell according to an embodiment of the invention;
fig. 4 is a schematic diagram of a second shielding shell according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Fig. 1 is a schematic structural diagram of a detection apparatus for a micro-current signal according to an embodiment of the present invention, and as shown in fig. 1, an embodiment of the present invention provides a detection apparatus for a micro-current signal, which includes a micro-current signal acquisition port 101, a micro-current signal amplification circuit 102, and a shielding housing 103, where:
the micro-current signal acquisition port 101 is used for shielding interference noise in the micro-current signal to obtain the micro-current signal after the interference noise is shielded, and the output end of the micro-current signal acquisition port 101 is connected with the micro-current signal amplification circuit 102.
In the embodiment of the invention, the micro-current signal is acquired through the micro-current signal acquisition port 101, and interference noises such as power frequency electromagnetic field, spike pulse, radio frequency noise, mechanical noise and the like in the pA (pico-ampere) level micro-current signal can be shielded, so that the micro-current signal after the interference noises are shielded is obtained.
The micro-current signal amplifying circuit 102 is arranged inside the shielding shell 103 and is used for amplifying the micro-current signal after shielding the interference noise to obtain a target micro-current signal so as to obtain a signal detection result according to the target micro-current signal.
In the embodiment of the present invention, the micro-current signal amplifying circuit 102 amplifies the micro-current signal after shielding the interference noise, so as to output a stable standard signal voltage, that is, a target micro-current signal, so that a subsequent detection circuit detects the target micro-current signal.
The shielding housing 103 is configured to shield the micro-current signal amplifying circuit 102 from interference signals. In the embodiment of the present invention, the shielding case 103 shields external interference signals, so that the micro-current signal amplifying circuit 102 has stronger interference resistance when performing amplification processing.
The detection device for the micro-current signal provided by the embodiment of the invention has higher detection precision and better anti-interference capability on external interference signals when the micro-current signal is detected.
On the basis of the foregoing embodiment, fig. 2 is a circuit schematic diagram of a micro-current signal amplifying circuit according to an embodiment of the present invention, and as shown in fig. 2, in the embodiment of the present invention, the micro-current signal amplifying circuit includes a first amplifying circuit module 1021 and a second amplifying circuit module 1022, where:
the first amplifying circuit module 1021 is a U1A composed of a first resistor R1, a second resistor R2, a third resistor R3, a fifth resistor R5, a seventh resistor R7, a first capacitor C1, a second capacitor C2, a third capacitor C3, a fourth capacitor C4 and a first operational amplifier; specifically, a first end of the first resistor R1 is connected to a second end of the first capacitor C1, a second end of the second resistor R2, a first end of the third resistor R3 and a first end of the second capacitor, a second end of the first resistor R1 is grounded, a first end of the first capacitor is connected to a first end of the second resistor R2, a second end of the fifth resistor R5 and a first input end of the first operational amplifier U1A, a second end of the third resistor R3 is connected to a second end of the second capacitor C2, an output end of the first operational amplifier UIA and an input end of the second amplification circuit module 1022, a first end of the third capacitor C3 is grounded, a second end of the third capacitor C3 is connected to a negative electrode of the driving power supply and a first driving end of the first operational amplifier UIA, a first end of the fourth capacitor C4 is grounded, a second end of the fourth capacitor C4 is connected to a positive electrode of the driving power supply and a second driving end of the first operational amplifier UIA, a first end of the fifth resistor R5 is connected to the input end of the first amplification circuit module 1022, a first end of the seventh resistor R7 is connected to ground, and a second end of the seventh resistor R7 is connected to a second input terminal of the first operational amplifier U1A.
Further, the second amplifying circuit module 1022 is composed of a fourth resistor R4, a sixth resistor R6, an eighth resistor R8, and a second operational amplifier U1B. Referring to fig. 2, in the embodiment of the present invention, a first end of a sixth resistor R6 is connected to the output end of the first amplifying circuit module 1021, a second end of the sixth resistor R6 is connected to the first end of a fourth resistor R4 and the first input end of the second operational amplifier U1B, a second end of the fourth resistor R4 is connected to the output end of the second operational amplifier U1B and the output end of the micro-current amplifying circuit, a first end of an eighth resistor R8 is grounded, and a second end of the eighth resistor R8 is connected to the second input end of the second operational amplifier U1B.
In an embodiment of the present invention, referring to fig. 2, the I-V conversion circuit of the T-type resistor network structure formed by the first amplifying circuit module 1021 and the second amplifying circuit module 1022 obtains higher sensitivity through a smaller resistance value. Specifically, in the embodiment of the present invention, the second resistor R2 is 0603 type, and has a resistance value ranging from 800M Ω to 1G Ω; the first resistor R1 is of 0603 type, and the resistance value ranges from 10K to 100K; the third resistor R3 is of 0603 type, and has a resistance value ranging from 47K to 470K; the fifth R5, the seventh resistor R7 and the eighth resistor R8 are 0603 type, and the resistance values are all 10K; the sixth resistor R6 is of 0603 type and has a resistance value of 100K; the fourth resistor R4 is of 0603 type, and the resistance value ranges from 100K to 900K; the first capacitor C1 is of 0603 type, and has a capacitance value ranging from 10 to 100 pF; the second capacitor C2, the third capacitor C3 and the fourth capacitor C4 are of 0603 type, and the capacitance values are all 100 nF;
when the second resistor R2' is connected to the third resistor R3, the corresponding input-output relationship is as follows:
VO＝-IiR2(1+R3/R1)；
the response time constant relationship is as follows:
τ＝R2×C1；
according to the first amplification circuit module 1021 and the second amplification circuit module 1022 provided by the embodiment of the invention, the TI ultralow input bias current operational amplifier chip is adopted, the selection of the feedback resistor is only in the level of M omega, the temperature drift error is reduced, meanwhile, the higher input resistor and the larger amplification factor are obtained, the stable condition of the circuit and the loop compensation circuit are further determined by analyzing the reliability of the circuit loop, the influence factor of the circuit bandwidth is solved, and the waveform distortion degree is reduced. And then, a standard signal voltage for signal detection, namely a target micro-current signal, can be stably output through a post-stage filter circuit, so that the detection of the micro-current is finished.
On the basis of the above embodiment, the shield case includes a first shield case and a second shield case, wherein:
the first shielding shell is used for shielding the first amplifying circuit module from interference signals, and the first amplifying circuit module is arranged in the first shielding shell;
the second shielding shell is used for shielding the micro-current signal amplification circuit, and the first amplification circuit module, the second amplification circuit module and the first shielding shell are arranged inside the second shielding shell.
In an embodiment of the present invention, fig. 3 is a schematic diagram of a first shielding shell according to an embodiment of the present invention, and referring to fig. 3, a first amplifying circuit module is disposed inside a first shielding shell 301, so as to locally protect a micro-current signal input into the first amplifying circuit module; fig. 4 is a schematic diagram of a second shielding shell according to an embodiment of the present invention, and as shown in fig. 4, the second shielding shell 401 wraps the entire circuit board therein, and only the input end 402 of the micro-current signal collecting port is exposed, so as to perform overall signal protection on the micro-current signal amplifying circuit.
Further, on the basis of the above embodiment, the first shielding shell 301 is made of a metal material, and the second shielding shell 401 is made of an aluminum material, so that the shielding structure has the characteristics of strong anti-interference capability, high modularization degree, light appearance quality, small volume and the like. As shown in fig. 4, the second shielding shell 401 has a rectangular structure and a specification of 45 × 13 × 28mm, the first shielding shell is connected to a board PCB ground signal of the micro-current signal amplifying circuit, and the fixing hole 403 for the board PCB ground signal is fixedly disposed at the bottom of the second shielding shell 401, so that the second shielding shell 401 is connected to ground.
According to the embodiment of the invention, two groups of interference signal shielding shells are arranged, so that the waveform anti-interference capability is improved, more effective data support is provided for data processing of an explosive detection instrument, and the detection resolution of an explosive sample is improved while the detection precision of equipment is improved.
On the basis of the above embodiment, the first amplification circuit module is provided with a guard ring, and the guard ring is obtained by performing guard ring processing on an input end of the first amplification circuit module.
The existing signal transmission uses a shielding cable to shield interference signals, and the shielding layer is usually grounded, so that a shielding capacitor, i.e. a parasitic capacitor between an input lead and the shielding layer, is introduced, and the shielding capacitor affects the operational accuracy and stability of the circuit, so that the pA-level current is easily submerged by the shielding capacitor. In the embodiment of the present invention, referring to fig. 2, the input end of the shielding layer (the first amplifying circuit module 1021) is looped, that is, a guard loop process is performed, so as to avoid generating a parasitic capacitance.
On the basis of the above embodiment, the micro-current signal acquisition port is an MMCX connector.
Based on the above embodiment, the interface diameter of the MMCX connector is not more than 5mm, and the impedance is 50 ohms.
Before the micro-current signal is amplified, a stable and low-noise signal current source needs to be input. The existing micro-current signal input end generally adopts a BNC radio frequency coaxial cable connector as a signal input interface for signal input and shielding, and an outer grounding shielding layer of the interface surrounds a central conductor to ensure good transmission of weak signals. However, the BNC rf coaxial cable connector has a large volume, and the corresponding wires are thick, hard and have a low bending degree, which results in a low utilization rate of the internal space of the BNC rf coaxial cable connector for a portable device with a compact internal structure. In the embodiment of the invention, the micro-current signal acquisition port is an MMCX connector with 50-ohm impedance, the cut-off frequency DC-6GHz, the diameter of the interface is not more than 5mm, and optionally, the interface plug-in tortuosity is 90 degrees or 180 degrees. The detection device for the micro-current signal provided by the embodiment of the invention has the characteristics of small volume, convenience in plugging and the like, and the wire rod has better flexibility and can be suitable for bending and expanding in a small space.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (7)
1. The utility model provides a detection device for little current signal which characterized in that, includes little current signal acquisition port, little current signal amplifier circuit and shielding shell, wherein:
the micro-current signal acquisition port is used for shielding interference noise in the micro-current signal to obtain the micro-current signal after the interference noise is shielded, and the output end of the micro-current signal acquisition port is connected with the micro-current signal amplification circuit;
the micro-current signal amplifying circuit is arranged in the shielding shell and used for amplifying the micro-current signal after shielding the interference noise to obtain a target micro-current signal so as to obtain a signal detection result according to the target micro-current signal;
and the shielding shell is used for shielding the micro-current signal amplifying circuit from interference signals.
2. The detection apparatus for a micro-current signal according to claim 1, wherein the micro-current signal amplification circuit comprises a first amplification circuit module and a second amplification circuit module, wherein:
the first amplifying circuit module consists of a first resistor, a second resistor, a third resistor, a fifth resistor, a seventh resistor, a first capacitor, a second capacitor, a third capacitor, a fourth capacitor and a first operational amplifier;
the second amplifying circuit module is composed of a fourth resistor, a sixth resistor, an eighth resistor and a second operational amplifier.
3. The detection device for micro-current signals according to claim 2, wherein the shielding enclosure comprises a first shielding enclosure and a second shielding enclosure, wherein:
the first shielding shell is used for shielding the first amplifying circuit module from interference signals, and the first amplifying circuit module is arranged in the first shielding shell;
the second shielding shell is used for shielding the micro-current signal amplification circuit, and the first amplification circuit module, the second amplification circuit module and the first shielding shell are arranged inside the second shielding shell.
4. The device according to claim 3, wherein the first shielding shell is made of metal, the second shielding shell is made of aluminum, the first shielding shell is connected with a PCB ground signal of the micro-current signal amplifying circuit, and a fixing hole of the PCB ground signal is fixedly arranged at the bottom of the second shielding shell, so that the second shielding shell is connected with the ground.
5. The apparatus according to claim 2, wherein a guard ring is disposed in the first amplifying circuit module, and the guard ring is obtained by performing guard ring processing on the input terminal of the first amplifying circuit module.
6. The detection device for microcurrent signal according to claim 1, wherein the microcurrent signal acquisition port is an MMCX connector.
7. The detection device for micro-current signals according to claim 5, wherein the interface diameter of the MMCX connector is not greater than 5mm, and the impedance is 50 ohms.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911326753.0A CN111077358A (en) | 2019-12-20 | 2019-12-20 | Detection device for micro-current signal |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911326753.0A CN111077358A (en) | 2019-12-20 | 2019-12-20 | Detection device for micro-current signal |
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| CN111077358A true CN111077358A (en) | 2020-04-28 |
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| CN201911326753.0A Pending CN111077358A (en) | 2019-12-20 | 2019-12-20 | Detection device for micro-current signal |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112290899A (en) * | 2020-10-26 | 2021-01-29 | 杭州爱华仪器有限公司 | Measuring circuit preamplifier |
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2019
- 2019-12-20 CN CN201911326753.0A patent/CN111077358A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112290899A (en) * | 2020-10-26 | 2021-01-29 | 杭州爱华仪器有限公司 | Measuring circuit preamplifier |
| CN112290899B (en) * | 2020-10-26 | 2024-02-06 | 杭州爱华仪器有限公司 | Preamplifier of measuring circuit |
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