CN105137162A - pA current detector - Google Patents
pA current detector Download PDFInfo
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- CN105137162A CN105137162A CN201510451837.2A CN201510451837A CN105137162A CN 105137162 A CN105137162 A CN 105137162A CN 201510451837 A CN201510451837 A CN 201510451837A CN 105137162 A CN105137162 A CN 105137162A
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Abstract
The invention relates to a pA current detector, which comprises a low noise system power supply circuit, a current-voltage conversion circuit, an analog-digital reference source circuit and an analog-to-digital conversion circuit, wherein the low noise system power supply circuit is used for providing low-noise power for the current-voltage conversion circuit, the reference source circuit and the analog-to-digital conversion circuit; the current-voltage conversion circuit is used for converting a signal source current signal into a voltage signal; the analog-digital reference source circuit is used for providing a reference source for the analog-to-digital conversion circuit; and the analog-to-digital conversion circuit is used for converting an output analog voltage signal of the current-voltage conversion circuit into a digital signal and sending the digital signal to a rear single chip microcomputer for treatment. PA current can be accurately sampled.
Description
Technical field
The present invention relates to micro-current detection technology field, particularly relate to a seed coat peace level current detector.
Background technology
Along with the development of science and technology, current detection technology is also in develop rapidly, from detecting that the electric current of nA rank even can detect the electric current of fA rank till now before, the mankind have entered the fA electric current epoch, and how can stablize the accurate pA level electric current that detects is that the emphasis of current detection technology development is with crucial.
Summary of the invention
Technical matters to be solved by this invention is to provide a seed coat peace level current detector, skin of can accurately sampling peace level electric current.
The technical solution adopted for the present invention to solve the technical problems is: provide a seed coat peace level current detector, comprise low noise system power supply circuit, current-voltage conversion circuit, modulus reference source circuit and analog to digital conversion circuit, described low noise system power supply circuit is used for providing low noise power supply to described current-voltage conversion circuit, reference source circuit and analog to digital conversion circuit; Described current-voltage conversion circuit is used for converting signal source current signal to voltage signal; Described modulus reference source circuit is used for providing reference source to analog to digital conversion circuit; Analog-digital conversion circuit as described is used for converting the output analog voltage signal of current-voltage conversion circuit to digital signal and gives the process of rear class single-chip microcomputer.
Described low noise system power supply circuit comprises the TPS4901 chip of three pieces of Texas Instrument and the TPS3001 chip of Liang Kuai Texas Instrument; Described three pieces of TPS4901 chips are used for inputting+15V voltage transitions and become+8V voltage ,+3.3V voltage and+2.5V voltage; Described two pieces of TPS3001 chips are used for inputting-15V voltage transitions and become-8V voltage and-2.5V voltage.
Described current-voltage conversion circuit comprises operational amplifier; The reverse input end of described operational amplifier connects signal source current signal, positive input ground connection; A glass tube resistance is also connected with between the output terminal of described operational amplifier and reverse input end.
The output terminal of described operational amplifier and reverse input end all adopt Teflon material to be fixed connection.
Described glass tube resistance two ends are also parallel with the electric capacity with glass tube.
Described operational amplifier is the AD549 of Ya De promise semiconductor; The resistance of described glass tube resistance is 1G ohm; The capacitance of described electric capacity is 5pF.
Described modulus reference source circuit is made up of the ADR4520 chip of Ya De promise semiconductor, for being exported at 2.048V voltage by the 3.3V voltage stabilization of input.
Analog-digital conversion circuit as described is made up of the AD7175-2 chip of Ya De promise semiconductor.
Beneficial effect
Owing to have employed above-mentioned technical scheme, the present invention compared with prior art, has following advantage and good effect: the present invention can stablize and accurately detects pA level current signal, has more accuracy than the method for traditional detection current signal, circuit scale is less simultaneously, more simply.
Accompanying drawing explanation
Fig. 1 is system chart of the present invention;
Fig. 2 is low noise power supply connection diagram in the present invention;
Fig. 3 is the schematic diagram of current-to-voltage converting circuit in the present invention;
Fig. 4 is analog to digital conversion circuit schematic diagram in the present invention.
Embodiment
Below in conjunction with specific embodiment, set forth the present invention further.Should be understood that these embodiments are only not used in for illustration of the present invention to limit the scope of the invention.In addition should be understood that those skilled in the art can make various changes or modifications the present invention, and these equivalent form of values fall within the application's appended claims limited range equally after the content of having read the present invention's instruction.
Embodiments of the present invention relate to a seed coat peace level current detector, as shown in Figure 1, comprise low noise system power supply circuit, current-voltage conversion circuit, modulus reference source circuit and analog to digital conversion circuit, described low noise system power supply circuit is used for providing low noise power supply to described current-voltage conversion circuit, reference source circuit and analog to digital conversion circuit; Described current-voltage conversion circuit is used for converting signal source current signal to voltage signal; Described modulus reference source circuit is used for providing reference source to analog to digital conversion circuit; Analog-digital conversion circuit as described is used for converting the output analog voltage signal of current-voltage conversion circuit to digital signal and gives the process of rear class single-chip microcomputer.
As shown in Figure 2, described low noise system power supply circuit comprises the TPS4901 chip of three pieces of Texas Instrument and the TPS3001 chip of Liang Kuai Texas Instrument; Described three pieces of TPS4901 chips are used for inputting+15V voltage transitions and become+8V voltage ,+3.3V voltage and+2.5V voltage; Described two pieces of TPS3001 chips are used for inputting-15V voltage transitions and become-8V voltage and-2.5V voltage, for system provides required power supply.This power supply is low noise power supply, and characteristic noise is less than 20uV, and the noise that whole exquisite system is produced by Power supply reaches minimum, and in other words, the ripple of power supply is less than 20uV, makes the output of system can not produce fluctuation because of ripple for this reason.
As shown in Figure 3, current-voltage conversion circuit is used for converting signal source current signal to voltage signal so that analog to digital conversion circuit collection.This circuit is built into I-V (current-voltage) change-over circuit, comprises operational amplifier; The reverse input end of described operational amplifier connects signal source current signal, positive input ground connection; Also be connected with one between the output terminal of described operational amplifier and reverse input end and amplify resistance.Wherein, operational amplifier adopts the AD549 of Ya De promise semiconductor, this amplifier has low maladjustment voltage (500uV), ultralow bias current (40fA), amplifying resistance adopts the glass tube resistance of 1G to amplify, this ohmic leakage stream with glass tube is very little, and temperature stability is very high.In order to accelerate the reaction time and increase bandwidth, can at the electric capacity with glass tube amplifying a resistance two ends 5pF in parallel.Reverse input end and the output terminal of AD549 are not connected directly between on pcb board, but adopt the good Teflon material of insulating coefficient to be fixed connection, and this measure is also to reduce leakage current.
As shown in Figure 4, modulus reference source circuit is used for providing reference source to analog to digital conversion circuit.This reference source circuit mainly provides a high precision to analog to digital conversion circuit, high stability reference voltage signal.This reference power supply chip adopts the ADR4520 of Ya De promise semiconductor, input 3.3V is stabilized in 2.048V, for modulus sample circuit provides reference source.Analog to digital conversion circuit is used for converting the output analog voltage signal of current-to-voltage converting circuit to digital signal and gives the process of rear class single-chip microcomputer.Modulus conversion chip adopts the AD7175-2 of Ya De promise semiconductor, is the ADC chip of 24, has the advantages that also there are 20 bit resolutions when sample frequency is 600hz, can meet the demand of system accuracy.
Claims (8)
1. a seed coat peace level current detector, comprise low noise system power supply circuit, current-voltage conversion circuit, modulus reference source circuit and analog to digital conversion circuit, it is characterized in that, described low noise system power supply circuit is used for providing low noise power supply to described current-voltage conversion circuit, reference source circuit and analog to digital conversion circuit; Described current-voltage conversion circuit is used for converting signal source current signal to voltage signal; Described modulus reference source circuit is used for providing reference source to analog to digital conversion circuit; Analog-digital conversion circuit as described is used for converting the output analog voltage signal of current-voltage conversion circuit to digital signal and gives the process of rear class single-chip microcomputer.
2. skin peace level current detector according to claim 1, it is characterized in that, described low noise system power supply circuit comprises the TPS4901 chip of three pieces of Texas Instrument and the TPS3001 chip of Liang Kuai Texas Instrument; Described three pieces of TPS4901 chips are used for inputting+15V voltage transitions and become+8V voltage ,+3.3V voltage and+2.5V voltage; Described two pieces of TPS3001 chips are used for inputting-15V voltage transitions and become-8V voltage and-2.5V voltage.
3. skin peace level current detector according to claim 1, it is characterized in that, described current-voltage conversion circuit comprises operational amplifier; The reverse input end of described operational amplifier connects signal source current signal, positive input ground connection; A glass tube resistance is also connected with between the output terminal of described operational amplifier and reverse input end.
4. skin peace level current detector according to claim 3, it is characterized in that, the output terminal of described operational amplifier and reverse input end all adopt Teflon material to be fixed connection.
5. skin peace level current detector according to claim 3, it is characterized in that, described glass tube resistance two ends are also parallel with the electric capacity with glass tube.
6. skin peace level current detector according to claim 5, it is characterized in that, described operational amplifier is the AD549 of Ya De promise semiconductor; The resistance of described glass tube resistance is 1G ohm; The capacitance of described electric capacity is 5pF.
7. skin peace level current detector according to claim 1, it is characterized in that, described modulus reference source circuit is made up of the ADR4520 chip of Ya De promise semiconductor, for being exported at 2.048V voltage by the 3.3V voltage stabilization of input.
8. skin peace level current detector according to claim 1, it is characterized in that, analog-digital conversion circuit as described is made up of the AD7175-2 chip of Ya De promise semiconductor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201510451837.2A CN105137162A (en) | 2015-07-28 | 2015-07-28 | pA current detector |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201510451837.2A CN105137162A (en) | 2015-07-28 | 2015-07-28 | pA current detector |
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| CN105137162A true CN105137162A (en) | 2015-12-09 |
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| CN201510451837.2A Pending CN105137162A (en) | 2015-07-28 | 2015-07-28 | pA current detector |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107390009A (en) * | 2017-07-28 | 2017-11-24 | 北京无线电计量测试研究所 | A kind of micro-current test device and method |
| CN110456144A (en) * | 2019-09-04 | 2019-11-15 | 珠海市运泰利自动化设备有限公司 | A kind of nA grade current measurement system for test equipment |
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|---|---|---|---|---|
| CN107390009A (en) * | 2017-07-28 | 2017-11-24 | 北京无线电计量测试研究所 | A kind of micro-current test device and method |
| CN107390009B (en) * | 2017-07-28 | 2019-11-29 | 北京无线电计量测试研究所 | A kind of micro-current test device and method |
| CN110456144A (en) * | 2019-09-04 | 2019-11-15 | 珠海市运泰利自动化设备有限公司 | A kind of nA grade current measurement system for test equipment |
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Application publication date: 20151209 |
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