CN219085015U

CN219085015U - Micro-current detection circuit

Info

Publication number: CN219085015U
Application number: CN202223548273.9U
Authority: CN
Inventors: 张雷; 刘岩; 黎建爽; 段亚东; 温玉波; 潘雅敏
Original assignee: Qingdao Haiborui Microelectronics Research Institute Co ltd
Current assignee: Qingdao Haiborui Microelectronics Research Institute Co ltd
Priority date: 2022-12-28
Filing date: 2022-12-28
Publication date: 2023-05-26
Anticipated expiration: 2032-12-28

Abstract

The utility model provides a micro-current detection circuit, which comprises an ADA4530-1 type operational amplifier U1 and a MAX338 low-leakage-current eight-selection analog switch U2 connected with the ADA4530-1 type operational amplifier U1, wherein the ADA4530-1 type operational amplifier is connected with a signal input end, the MAX338 low-leakage-current eight-selection analog switch U2 is connected with at least eight groups of precision resistors, the ADA4530-1 type operational amplifier is connected with a first positive power supply and a first negative power supply, and the MAX338 low-leakage-current eight-selection analog switch is connected with a second positive power supply and a second negative power supply; the application adopts a precision current operational amplifier ADA4530-1 and a low leakage current eight-selection analog switch MAX338 to be externally connected with eight precision resistors, so that an eight-gear current detection circuit is formed; the measuring stability is good, and the precision is high.

Description

Micro-current detection circuit

Technical Field

The utility model relates to the technical field of microcurrent monitoring, in particular to a microcurrent detection circuit.

Background

In the field of weak signal monitoring, weak currents of uA and nA levels are often required to be measured, and the weak currents are generally smaller than 10 ^-6 The measurement of the current is called microcurrent measurement, the microcurrent detection belongs to one branch of weak signal detection, is a technology aiming at noise, focuses on how to suppress the noise and improve the signal to noise ratio, and has wide application in many fields of military reconnaissance, physics, electrochemistry, biomedicine, astronomy, geography, magnetism and the like; the current micro-current detection circuit has many defects, such as low measurement precision, poor measurement stability, large measurement error, too large influence of the measured value along with the change of temperature, easy interference of the measured value and the like.

Disclosure of Invention

The present utility model is directed to a micro-current detection circuit, which solves the above-mentioned problems of the prior art.

In order to achieve the above purpose, the present utility model provides the following technical solutions:

for microcurrent measurement there are generally the following methods: the utility model adopts an operational amplifier current feedback method with optimal performance;

a micro-current detection circuit comprises an ADA4530-1 type operational amplifier U1 and a MAX338 low-leakage-current eight-selection analog switch U2 connected with the ADA4530-1 type operational amplifier U1, wherein the ADA4530-1 type operational amplifier is connected with a signal input end, the MAX338 low-leakage-current eight-selection analog switch U2 is connected with at least eight groups of precise resistors, the ADA4530-1 type operational amplifier is connected with a first positive power supply and a first negative power supply, and the MAX338 low-leakage-current eight-selection analog switch is connected with a second positive power supply and a second negative power supply.

Preferably, the circuit comprises eight groups of precise resistors, namely a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7 and a resistor R8, wherein the reverse input end of the ADA4530-1 operational amplifier U1 is connected with one end of a resistor R0, the other end of the resistor R0 is respectively connected with one end of the signal input end, a capacitor C5 and one end of the resistor R1, the resistor R2, the resistor R3, the resistor R4, the resistor R5, the resistor R6, the resistor R7 and the resistor R8, and the other end of the resistor R1, the resistor R2, the resistor R3, the resistor R4, the resistor R5, the resistor R6, the resistor R7 and the other end of the resistor R8 are respectively connected with the 4 pin, the 5 pin, the 6 pin, the 7 pin, the 9 pin, the 10 pin, the 11 pin and the 12 pin of an analog switch U2 with low leakage current of MAX 338; the 1 pin, the 15 pin and the 16 pin of the MAX338 low leakage current eight-selection analog switch U2 are used as gain control ends, and the 2 pin of the MAX338 low leakage current eight-selection analog switch U2 is suspended; the other end of the capacitor C5 is connected with the 6 pin of the ADA4530-1 operational amplifier U1 and the 8 pin of the MAX338 low leakage current eighth one analog switch U2 to be used as a signal output end.

Preferably, the 5 pins of the ADA4530-1 type operational amplifier U1 are respectively connected with one end of a magnetic bead L1 and one end of a capacitor C1, and the other end of the magnetic bead L1 is connected with a first positive power supply; the other end of the capacitor C1 is grounded and is connected with the 14 pins of the MAX338 low leakage current eighth one analog switch U2 and the first end of the capacitor C2, and the first end of the capacitor C2 is grounded and is connected with the 1 pin and the 3 pin of the ADA4530-1 type operational amplifier U1; the magnetic bead L1 and the capacitor C1 form an LC filter circuit of a first positive power supply;

the 4 pins of the ADA4530-1 operational amplifier U1 are respectively connected with one end of the magnetic bead L2 and the second end of the capacitor C2, the other end of the magnetic bead L2 is connected with a first negative power supply, and the magnetic bead L2 and the capacitor C2 form an LC filter circuit of the first negative power supply;

13 pins of MAX338 low leakage current eight-selection analog switch U2 are connected with one end of magnetic bead L2 and one end of capacitor C3, the other end of magnetic bead L2 is connected with a second positive power supply, and the other end of capacitor C3 is grounded; the 3 feet of the MAX338 low leakage current eight-selection analog switch U2 are connected with the magnetic bead L4 and one end of the capacitor C4, the other end of the magnetic bead L4 is connected with the second negative power supply, and the other end of the capacitor C4 is grounded.

Preferably, A2, A1 and A0 of the analog switch U2 are eight switch control ends, and one of eight feedback resistors R1, R2, R3, R4, R5, R6, R7 and R8 can be selected according to the detected current.

Wherein, the corresponding relation is as follows: when a2a1a0=000, the feedback resistance is R1; when a2a1a0=001, the feedback resistance is R2; when a2a1a0=010, the feedback resistance is R3; a2a1a0=011, the feedback resistance is R4; when a2a1a0=100, the feedback resistance is R5; when a2a1a0=101, the feedback resistance is R6; when a2a1a0=110, the feedback resistance is R7; when a2a1a0=111, the feedback resistance is R8.

Preferably, the first positive power supply and the first negative power supply are respectively a positive 5V power supply and a negative 5V power supply; the second positive power supply and the second negative power supply are respectively a positive 15V power supply and a negative 15V power supply.

The circuit is powered by four paths of power supplies, namely positive and negative 5V and positive and negative 15V, the positive and negative 5V supply power to the precision current operational amplifier U1, the magnetic bead L1 and the capacitor C1 are LC filter circuits of positive 5V power supplies, the magnetic bead L2 and the capacitor C2 are LC filter circuits of negative 5V power supplies, the magnetic bead L3 and the capacitor C3 are LC filter circuits of positive 15V power supplies, the magnetic bead L4 and the capacitor C4 are LC filter circuits of negative 15V power supplies, and each path of power supply is added with one-stage LC filter circuit, so that the stability and low noise of the four paths of power supplies can be ensured, and the accuracy of current detection is improved. The detected small current signal enters the inverting input end of the precision current operational amplifier U1 through the buffer resistor R0, one gear of the U2 is selected according to the detected current, the operational amplifier U1 converts the small current signal into a voltage signal, the voltage signal is output by the 8 pins of the U2, and the capacitor C5 is a feedback capacitor output to the input, so that the stability of the operational amplifier is improved.

Compared with the prior art, the utility model provides a micro-current detection circuit, which has the following beneficial effects: the application adopts a precision current operational amplifier ADA4530-1 and a low leakage current eight-selection analog switch MAX338 to be externally connected with eight precision resistors, so that an eight-gear current detection circuit is formed; the measuring stability is good, and the precision is high.

Drawings

Fig. 1 is a schematic structural view of the present utility model.

Detailed Description

The following description of the embodiments of the present utility model will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present utility model, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without making any inventive effort, are intended to be within the scope of the utility model.

Referring to fig. 1, a micro-current detection circuit includes an ADA4530-1 type operational amplifier U1 and a MAX338 low leakage current eighth selection analog switch U2 connected to the ADA4530-1 type operational amplifier U1, the ADA4530-1 type operational amplifier is connected to a signal input end, the MAX338 low leakage current eighth selection analog switch U2 is connected to at least eight groups of precision resistors, the ADA4530-1 type operational amplifier is connected to a first positive power supply and a first negative power supply, and the MAX338 low leakage current eighth selection analog switch is connected to a second positive power supply and a second negative power supply.

ADA4530-1 is a class fA (10-15A) input bias current operational amplifier, useful as an electrometer with integrated protection buffers, having an operating voltage range of 4.5V to 16V, enabling operation in conventional 5V and 10V single power supply systems and + -2.5V and + -5V dual power supply systems; in addition, the new ADA4530 adopts a CMOS process, and the operational amplifier is added with a special ESD diode circuit in design, and the buffer is used to force the currents of D1, D2, D3 and D4 to be 0, so that the problem of leakage current generated by adding diodes before is avoided by the special design, thereby improving ESD performance, and meanwhile, the index of bias current is not influenced. Thus, the ESD performance index of ADA4530 reaches +/-4000V, and the bias current performance is only 20fA at maximum between 20 ℃ and 85 ℃;

the circuit comprises eight groups of precise resistors, namely a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7 and a resistor R8, wherein the reverse input end of an ADA4530-1 type operational amplifier U1 is connected with one end of a resistor R0, the other end of the resistor R0 is respectively connected with one end of a signal input end and a capacitor C5, one end of the resistor R1, the resistor R2, the resistor R3, the resistor R4, the resistor R5, the resistor R6, the resistor R7 and one end of the resistor R8, and the other end of the resistor R1, the resistor R2, the resistor R3, the resistor R4, the resistor R5, the resistor R6, the resistor R7 and the other end of the resistor R8 are respectively connected with 4 pins, 5 pins, 6 pins, 7 pins, 9 pins, 10 pins, 11 pins and 12 pins of an MAX338 low leakage current eight analog switch U2; the 1 pin, the 15 pin and the 16 pin of the MAX338 low leakage current eight-selection analog switch U2 are used as gain control ends, and the 2 pin of the MAX338 low leakage current eight-selection analog switch U2 is suspended; the other end of the capacitor C5 is connected with the 6 pin of the ADA4530-1 type operational amplifier U1 and the 8 pin of the MAX338 low leakage current eighth one analog switch U2 to be used as signal output ends, the 5 pin of the ADA4530-1 type operational amplifier U1 is respectively connected with one end of the magnetic bead L1 and one end of the capacitor C1, and the other end of the magnetic bead L1 is connected with a first positive power supply; the other end of the capacitor C1 is grounded and is connected with the 14 pins of the MAX338 low leakage current eighth one analog switch U2 and the first end of the capacitor C2, and the first end of the capacitor C2 is grounded and is connected with the 1 pin and the 3 pin of the ADA4530-1 type operational amplifier U1; the magnetic bead L1 and the capacitor C1 form an LC filter circuit of a first positive power supply; the 4 pins of the ADA4530-1 operational amplifier U1 are respectively connected with one end of the magnetic bead L2 and the second end of the capacitor C2, the other end of the magnetic bead L2 is connected with a first negative power supply, and the magnetic bead L2 and the capacitor C2 form an LC filter circuit of the first negative power supply; 13 pins of MAX338 low leakage current eight-selection analog switch U2 are connected with one end of magnetic bead L2 and one end of capacitor C3, the other end of magnetic bead L2 is connected with a second positive power supply, and the other end of capacitor C3 is grounded; the 3 feet of the MAX338 low leakage current eight-selection analog switch U2 are connected with the magnetic bead L4 and one end of the capacitor C4, the other end of the magnetic bead L4 is connected with the second negative power supply, and the other end of the capacitor C4 is grounded.

The analog switch U2 has one switch control end selected from A2, A1 and A0, and one of eight feedback resistors R1, R2, R3, R4, R5, R6, R7 and R8 can be selected according to the detected current, wherein the corresponding relation is as follows: when a2a1a0=000, the feedback resistance is R1; when a2a1a0=001, the feedback resistance is R2; when a2a1a0=010, the feedback resistance is R3; a2a1a0=011, the feedback resistance is R4; when a2a1a0=100, the feedback resistance is R5; when a2a1a0=101, the feedback resistance is R6; when a2a1a0=110, the feedback resistance is R7; when a2a1a0=111, the feedback resistor is R8, and the first positive power supply and the first negative power supply are respectively a positive 5V power supply and a negative 5V power supply; the second positive power supply and the second negative power supply are respectively a positive 15V power supply and a negative 15V power supply.

Although embodiments of the present utility model have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made therein without departing from the principles and spirit of the utility model, the scope of which is defined in the appended claims and their equivalents.

Claims

1. A micro-current detection circuit is characterized in that: the high-voltage power supply comprises an ADA4530-1 type operational amplifier U1 and a MAX338 low-leakage-current eight-selection analog switch U2 connected with the ADA4530-1 type operational amplifier U1, wherein the ADA4530-1 type operational amplifier is connected with a signal input end, the MAX338 low-leakage-current eight-selection analog switch U2 is connected with at least eight groups of precise resistors, the ADA4530-1 type operational amplifier is connected with a first positive power supply and a first negative power supply, and the MAX338 low-leakage-current eight-selection analog switch is connected with a second positive power supply and a second negative power supply.

2. The microcurrent detection circuit of claim 1 wherein: the circuit comprises eight groups of precise resistors, namely a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7 and a resistor R8, wherein the reverse input end of an ADA4530-1 type operational amplifier U1 is connected with one end of a resistor R0, the other end of the resistor R0 is respectively connected with one end of a signal input end and a capacitor C5, and one end of the resistor R1, the resistor R2, the resistor R3, the resistor R4, the resistor R5, the resistor R6, the resistor R7 and the resistor R8, and the other end of the resistor R1, the resistor R2, the resistor R3, the resistor R4, the resistor R5, the resistor R6, the resistor R7 and the resistor R8 are respectively connected with the 4 pins, the 5 pins, the 6 pins, the 7 pins, the 9 pins, the 10 pins, the 11 pins and the 12 pins of an MAX338 low leakage current eight analog switch U2; the 1 pin, the 15 pin and the 16 pin of the MAX338 low leakage current eight-selection analog switch U2 are used as gain control ends, and the 2 pin of the MAX338 low leakage current eight-selection analog switch U2 is suspended; the other end of the capacitor C5 is connected with the 6 pin of the ADA4530-1 operational amplifier U1 and the 8 pin of the MAX338 low leakage current eighth one analog switch U2 to be used as a signal output end.

3. The microcurrent detection circuit of claim 1 wherein: the 5 pins of the ADA4530-1 operational amplifier U1 are respectively connected with one end of a magnetic bead L1 and one end of a capacitor C1, and the other end of the magnetic bead L1 is connected with a first positive power supply; the other end of the capacitor C1 is grounded and is connected with the 14 pins of the MAX338 low leakage current eighth one analog switch U2 and the first end of the capacitor C2, and the first end of the capacitor C2 is grounded and is connected with the 1 pin and the 3 pin of the ADA4530-1 type operational amplifier U1; the magnetic bead L1 and the capacitor C1 form an LC filter circuit of a first positive power supply;

4. The microcurrent detection circuit of claim 1 wherein: the analog switch U2 has one switch control end A2, one switch control end A1 and one switch control end A0, and one of eight feedback resistors R1, R2, R3, R4, R5, R6, R7 and R8 can be selected according to the detected current.

5. The microcurrent detection circuit of claim 1 wherein: the first positive power supply and the first negative power supply are respectively a positive 5V power supply and a negative 5V power supply; the second positive power supply and the second negative power supply are respectively a positive 15V power supply and a negative 15V power supply.