CN109239432A - A kind of weak current circuit of nitrogen oxide sensor - Google Patents
A kind of weak current circuit of nitrogen oxide sensor Download PDFInfo
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- CN109239432A CN109239432A CN201810836245.6A CN201810836245A CN109239432A CN 109239432 A CN109239432 A CN 109239432A CN 201810836245 A CN201810836245 A CN 201810836245A CN 109239432 A CN109239432 A CN 109239432A
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- G—PHYSICS
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
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- G01R19/0092—Arrangements for measuring currents or voltages or for indicating presence or sign thereof measuring current only
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Abstract
The invention discloses a kind of weak current circuits of nitrogen oxide sensor, comprising: sequentially connected current-to-voltage converting circuit, differential low-pass filter and instrumentation amplifier；The current-to-voltage converting circuit is constituted by accessing sampling resistor in signal circuit, the current-to-voltage converting circuit is used to be converted to the current signal that nitrogen oxide sensor acquires N times of voltage signal；The voltage signal export after accurately and effectively amplifying by the instrumentation amplifier again after the differential low-pass filter filters out High-frequency Interference；Wherein the value of N is equal to the resistance value size of sampling resistor.The accurate amplification of weak voltage signals may be implemented in the present invention, and this magnifier has the characteristics that low imbalance, low output error, high s/n ratio, high cmrr, high-gain.
Description
Technical field
The invention belongs to signal detection fields, more particularly, to a kind of faint electricity applied to automobile-used nitrogen oxide sensor
Current detection circuit.
Background technique
With the high speed development of world economy, Global Auto total amount persistently rises, and the development of auto industry is largely
The progress of human society is promoted, but due to the limitation of its power resources, also largely exacerbates environmental pollution and the energy
Shortage.Automobile-used nitrogen oxide sensor will test result and feed back to Motronic control maps control by the oxygen concentration in detection vehicle exhaust
Unit (ECU) processed improves fuel combustion utilization rate, also, improves the catalysis of three-way catalyst in vehicle maintenance service system
Efficiency, the effective noxious gas emission reduced including NO.
The combustion utilization efficiency of fuel is to be changed by adjusting the concentration of institute's oxygen, and the concentration of NO is catalyzed by it
What the oxygen concentration generated after reaction changed.Automobile-used nitrogen oxide sensor application in, oxygen, nitrogen oxygen concentration further through electric current
Size reaction therefore in order to accurately learn that the concentration of gas just must accurately measure its electric current, then pass through control electric current
It reaches a certain level, discharge standard is reached with the gas concentration guaranteed in vehicle exhaust.
According to the requirement of automobile exhaust emission standard, oxygen concentration and oxynitride concentration in tail gas are relatively low
, the especially concentration of oxynitrides, and the lower electric current very little for meaning that generation of concentration.This just needs us quasi-
Really, it quickly measures by the weak current of oxygen and oxynitrides generation.
This weak current circuit detection is complex, is mainly reflected in:
(1) low noise.Often carry such or such noise, this main packet of making an uproar secretly in faint input signal
Include the radio frequency interference at amplifier A1, A2 input terminal end, 1/f noise and broadband noise in amplifying circuit.Noise can be micro- in amplification
Be amplified when weak input signal, thus the noise of amplifying circuit entirety have to it is low.
(2) high-gain.Input signal is very faint, resolution ratio 0.1uA, measures for convenience, is passing through Current Voltage
After conversion, it is desirable that the amplification factor of amplifying circuit is sufficiently high.
(3) high cmrr.Difference mode signal voltage amplification factor is bigger, and common-mode voltage amplification is smaller, then common mode
Inhibit than bigger, it means that circuit is capable of the common-mode signal at effective suppression circuit both ends, enhances the anti-interference of detection circuit
Ability.
(4) low maladjustment voltage.Refer in the operational amplifier of difference amplifier or Differential Input, in order to be obtained in output end
Constant no-voltage output, and need to the DC voltage added by two input terminals difference.The sheet of this parameter characterization difference amplifier
Grade matching degree.When two input terminals of difference amplifier add equal input voltage, differential output voltage, which is known as exporting, to be lost
Adjust voltage.In amplifying circuit, offset voltage should be low as far as possible.
Summary of the invention
In view of the drawbacks of the prior art, the purpose of the present invention is to provide a kind of strong antijamming capability, measurement error it is low, point
Resolution reaches the weak current circuit of 0.1uA.
The present invention provides a kind of weak current circuits of nitrogen oxide sensor, comprising: sequentially connected Current Voltage
Conversion circuit, differential low-pass filter and instrumentation amplifier；By being accessed in signal circuit described in sampling resistor composition
Current-to-voltage converting circuit, the current-to-voltage converting circuit are used to the current signal that nitrogen oxide sensor acquires being converted to N times
Voltage signal；The voltage signal is put by the instrumentation op again after the differential low-pass filter filters out High-frequency Interference
Big device export after accurately and effectively amplifying；Wherein the value of N is equal to the resistance value size of the sampling resistor.
Wherein, the resistance value size of sampling resistor is 80 Ω.
Wherein, differential filter circuit includes: resistance R1a, resistance R1b, capacitor C1a, capacitor C1b and capacitor C2；The electricity
Hold C1a, the capacitor C2 and the capacitor C1b to be sequentially connected in series, the non-series connection end ground connection of the capacitor C1a is described
The non-series connection end of capacitor C1b is grounded, and the series connection end of the capacitor C1a and the capacitor C2 are as the differential filtering
Output of the series connection end of the output cathode of circuit, the capacitor C1b and the capacitor C2 as the differential filter circuit
Cathode；Input anode of the one end of the resistance R1a as the differential filter circuit, the other end of the resistance R1a and institute
Capacitor C1a is stated to connect with the series connection end of the capacitor C2；One end of the resistance R1b is as the differential filter circuit
Cathode is inputted, the other end of the resistance R1b is connect with the series connection end of the capacitor C1b and the capacitor C2.
Wherein, instrumentation amplifier includes: the first amplifier A1, the second amplifier A2, third amplifier A3, resistance R3, resistance
R4, resistance R5, resistance R6, resistance R7, resistance R8 and resistance R9；The normal phase input end of first amplifier A1 is as the instrumentation op
The inverting input terminal of the input anode of amplifier, the first amplifier A1 is inputted by the positive that resistance R3 is connected to the second amplifier A2
End, input cathode of the inverting input terminal of the second amplifier A2 as the instrumentation amplifier, the reverse phase of the first amplifier A1
Input terminal also passes through the output end that resistance R4 is connected to the first amplifier A1, and the normal phase input end of the second amplifier A2 is connected by resistance R5
It is connected to the output end of the second amplifier A2；The output end of first amplifier A1 passes through the resistance R6 being sequentially connected in series and connects with resistance R8
To the output end of third amplifier A3, the series connection end of resistance R6 and resistance R8 are connected to the normal phase input end of third amplifier A3；
The output end of second amplifier A2 passes through the resistance R7 being sequentially connected in series and resistance R9 ground connection；The series connection of resistance R7 and resistance R9 connect
Connect the inverting input terminal that end is connected to third amplifier A3；The output end of third amplifier A3 is as the defeated of the instrumentation amplifier
Outlet.
Compared with prior art, weak current circuit disclosed by the invention has following technological merit:
(1) low current signal for being difficult to detect accurately can be converted into voltage signal.Due to weak output signal, to protect
Demonstrate,prove voltage signal it is accurate it is necessary that sampling resistor it is accurate, after a variety of sampling resistors of contrast test, have chosen error
The sampling resistor for being 25ppm for 0.01%, temperature drift, this sampling resistor greatly reduce the conversion of current-to-voltage converting circuit
Error, and the very little that is acted upon by temperature changes；
(2) accurately amplify voltage signal, resolution ratio can reach 0.1uA.Voltage signal it is accurate amplification mainly by
To the influence of noise jamming and amplifier input offset voltage.Amplifying circuit has used the magnifier structure of three amplifiers, tool
There is high common-mode rejection ratio, and accessed a differential low-pass filter between input voltage signal and amplifying circuit,
Radiofrequency signal can effectively be inhibited, reduce the influence of noise, enhance the anti-interference ability of amplifying circuit；In addition, selected
Sampling resistor resistance value be 80 Ω, offset voltage 0.4uV, when current signal be 0.1uA when, input difference voltage signal
For 8uV, offset voltage accounts for the 5% of differential voltage, this value is smaller, and the three amplifier structures used are with extremely strong total
Mould rejection ability, and the input offset voltage of two amplifiers A1, A2 can be inhibited, therefore resolution ratio can reach 0.1uA.
Detailed description of the invention
Fig. 1 is the circuit diagram of nitrogen oxide sensor weak current circuit provided in an embodiment of the present invention；
Fig. 2 is current-to-voltage converting circuit in nitrogen oxide sensor weak current circuit provided in an embodiment of the present invention
Physical circuit figure；
Fig. 3 is the tool of differential low-pass filter in nitrogen oxide sensor weak current circuit provided in an embodiment of the present invention
Body circuit diagram；
Fig. 4 is the circuit analysis for causing output error；
Fig. 5 is instrumentation op amplifying circuit in nitrogen oxide sensor weak current circuit provided in an embodiment of the present invention
Physical circuit figure.
Specific embodiment
In order to make the objectives, technical solutions, and advantages of the present invention clearer, with reference to the accompanying drawings and embodiments, right
The present invention is further elaborated.It should be appreciated that the specific embodiments described herein are merely illustrative of the present invention, and
It is not used in the restriction present invention.
Weak current circuit provided by the invention includes: current-to-voltage converting circuit, differential low-pass filter and puts
Big circuit；Firstly, high-accuracy, Low Drift Temperature a sampling resistor is linked into signal circuit, Current Voltage conversion electricity is constituted
Original current signal is changed into voltage signal by road, and multiple is the sizes values of the sampling resistor of access；Then, after conversion
Voltage signal be flowed into differential low-pass filter circuit, filtering out the radio noise being mixed in weak voltage signals, reduce
The influence of noise improves signal-to-noise ratio；Finally, connect amplifying circuit after differential low-pass filter, this amplifying circuit be by
Several zero shift operational amplifiers and several resistance, capacitor are built.The amplification factor of circuit is 41200, current measurement point
Resolution is 0.1uA, and amplifying circuit amplifies voltage signal, and resolution ratio is mainly pressed down by the input offset voltage and common mode of amplifier used
The influence of ability processed.Firstly, 0.1uA current signal is after the sampling resistor of 80 Ω, the pressure difference at resistance both ends is
8uV, and the input offset voltage of selected amplifier is 0.4uV, accounts for the 5% of input pressure difference, the influence to input signal is very little
's；In addition circuit has high common mode inhibition capacity, can reduce the input for being present in two amplifiers of input amplifier
Offset voltage.
Wherein current-to-voltage converting circuit, in faint current signal loop, a high-accuracy, Low Drift Temperature of connecting, resistance
Value is the sampled voltage of 80 Ω, so that biggish voltage signal is converted by very faint current signal, so that rear class amplifies electricity
Road detection.
Wherein differential low-pass filter can solve the radio frequency commutation issue of rear class magnifier, i.e., in strong radio frequency
When interference, ESD diode, input structure and other non-linear elements can be in amplifier ins to radio frequency in amplifier
Signal is rectified, and is then embodied in the form of direct current output offset error；Meanwhile filter can be in entirely measurement band
Sufficiently high input impedance is maintained in wide, to avoid the load for increasing signal source.
Wherein magnifier can extract faint differential signal from stronger common-mode noise and interference, and accurately put
Greatly, measurement error is effectively reduced.As R4=R5, R6=R7, R8=R9, magnifier amplification factor is
In embodiments of the present invention, current-to-voltage converting circuit, in circuit signal circuit, electric current flows through sampling resistor, by
It is faint in current signal, sampling resistor resistance value answer it is larger, then the size of electric current can pass through the voltage response at resistance both ends
Out.In order to guarantee accurate kinetic current signal, high-precision sampling resistor need to be used, while to reduce temperature as far as possible
Fluctuation influences conversion bring, therefore sampling resistor should also have lower temperature drift.
In embodiments of the present invention, differential low-pass filter can be filtered out effectively in instrumentation amplifier input terminal
Radio frequency interference.In the presence of radio frequency interference, this interference will cause DC maladjustment error, that is to say, that amplified voltage
It is compared with theoretical value and has certain fluctuation, and this fluctuation can not be observed in measurement.Differential low-pass filter adds
It is added in the input end of signal, this radio frequency interference is completely cut off outside as far as possible, increases the anti-interference energy of late-class circuit
Power.
In embodiments of the present invention, amplifier A1, A2 improves the input impedance of amplifier A3 in magnifier, and fortune
The common mode inhibition capacity for putting A3 enhancesTimes, so that circuit has biggish common-mode rejection ratio.Meanwhile instrument is put
Resistance used in big circuit is the metalfilmresistor of 0.1% precision, Low Drift Temperature, ensure that amplifier A3 and R6, R7, R8,
The common mode rejection performance of the difference amplifier of R9 composition.
For further description nitrogen oxide sensor weak current circuit provided in an embodiment of the present invention, now in conjunction with
Specific example and details are as follows with reference to attached drawing:
The weak current circuit is applied to automobile-used nitrogen oxide sensor and pumps current measurement, when nitrogen oxide sensor works normally
When, it is 7uA that auxiliary pump, which pumps electric current Ip1, and measurement pump pump electric current Ip2 is 1~2uA, and this requires current detection circuit resolution ratio to reach
To 0.1uA, and there is lower measurement error.And measurement error mainly by noise, bias current, input imbalance (offset voltage,
Offset current) it causes, therefore, amplifying circuit should reduce the influence of three as far as possible.For above situation, a tool is devised
There are high s/n ratio (SNR), low input to lack of proper care, the detection circuit of high-gain.As shown, the circuit is mainly converted by I/V, is poor
Divide low-pass filter, amplifying circuit three parts composition.
Current-to-voltage converting circuit as shown in Figure 2, current signal loop include: internal resistance R, sampling resistor R0, R and R0 string
Connection.Current signal Is flows through R0 from top to bottom, and a voltage signal, value V are generated on resistance R0i+-Vi-, meet ohm
Law:Amplification factor K1=R0=80 Ω.
Differential low-pass filter as shown in Figure 3, R1a and C1a, R1b and C1b constitute two-way low-pass filtering, two resistance, electricity
Holding size should be identical as far as possible.Because if to will lead to bridge unbalance and reduce high frequency for the time constant mismatch of filter circuit
Common mode rejection performance, and this mismatch is very difficult to avoid completely.However, when in input terminal flying capcitor C2, it will be able to
It is effectively reduced caused by being mismatched because of R1a, R1b, C1a, C1b and exchanges common mode inhibition error.When C2 ratio C1a (C1a=C1b) is big by 10
Times when, common mode inhibition error caused by this connection type can mismatch capacitor be reduced to original 1/20, and filter
Device does not influence DC common-mode inhibition.
In Fig. 3, there are two types of different bandwidth, difference bandwidth and common mode bandwidth for rfi filter.The former refers to filter
Frequency response in circuit input end input differential signal ,-three dB bandwidth are as follows:The latter
Refer to that common mode radiofrequency signal is added in the frequency response between two input terminals and ground, therefore C2 does not influence common mode bandwidth ,-three dB bandwidth are as follows:In Fig. 3, -3dB differential signal bandwidth is about 7579Hz, increases C2 and R1a, R1b (R1a=
R1b its rf attenuation ability) can be enhanced, but resistance is too big can generate larger thermal noise.
In-phase proportion circuit output error analysis circuit as shown in Figure 4, it is used to analyze and put in the difference of instrument amplifier
Output error caused by the input imbalance of big device.In Fig. 4, input signal is flowed into in-phase end through resistance Rc, is flowed into amplifier
The electric current of in-phase end and reverse side is respectively IB+、IB-, offset current IOS=IB+-IB-, bias currentInput
Offset voltage VOSIndicate that output voltage is folded to the voltage on input terminal when two input end groundings.According to Ohm's law, with mutually defeated
Enter to hold voltage VP=-RcIB+, the output error as caused by electric current can be obtained using superposition theorem are as follows:Due to bias currentOffset current IOS=IB+-IB-, above formula can deform are as follows:Work as Rc=Ra||RbWhen, it obtains
It arrivesIt has thus obtained exporting caused by offset current and miss
Difference.
In-phase proportion circuit output error analysis circuit as shown in Figure 4, VOSFor the input offset voltage of operational amplifier,
The size of this value is related with the thermal drift of amplifier, common-mode rejection ratio, power supply rejection ratio, output swing, in the present invention, selected
The input offset voltage V of amplifierOSVery little is 0.4uV.The output error as caused by input offset voltage are as follows:Thus obtain whole output error are as follows:In general VOSWith IOSPolarity be arbitrary, then negative sign is just simultaneously
Do not mean that the two has the tendency that mutually compensating.Usually select VOSAnd IOSAll integrated transporting dischargings of very little, to guarantee output error
It is worth very little.
Instrumentation op amplifying circuit as shown in Figure 5, amplifying circuit have low noise, low biasing, low imbalance, high-gain
Feature.The operational amplifier of selection have low-voltage noise spectrum density, low current noise spectrum density, low maladjustment voltage,
Meanwhile circuit amplification factor with higher,
Shown in Fig. 5, A1 and A2 operational amplifier buffers input voltage.In this configuration, single gain resistor R3
It is connected between the summing junction of two input buffers, that is, has been connected to the inverting input terminal of two amplifiers.It is put due to each
The voltage of big device summing junction is equal to the voltage for being applied to respective positive input terminal, and therefore, entire differential input voltage is all presented now
At the both ends R3.Because the differential voltage that input voltage obtains after amplification is presented on this three resistance of R3, R4 and R5, that
, differential gain can be adjusted by only changing R3.In addition, this be connected with another advantage: once this is electric
After the matched resistor setting of the gain ratio on road, there will not be any requirement to resistors match again when changing gain.If
R4=R5, R6=R7, R8=R9 are then exported are as follows:
As shown in Figure 5, since the voltage at the both ends R3 is equal to Vin+-Vin-, so the electric current for flowing through R3 is (Vin+-Vin-)/
R3, therefore input signal will be obtained gain and be amplified by A1 and A2.However it is noted that it is added to amplifier in
Common-mode voltage in the both ends R3 current potential having the same, then, electric current would not be generated on R3.Due to there is no electric current to flow through
R3 also just flows through R4 and R5 without electric current, and amplifier A1 and A2 will work as unity gain follower.Therefore, common mode is believed
Number will be with unit gain by input buffer, and differential voltage will be byGain coefficient be amplified.This also just anticipates
Taste the circuit common-mode rejection ratio compared to being increased with original difference channelTimes.
Current-to-voltage converting circuit and instrumentation op amplifying circuit shown in fig. 5 as shown in connection with fig. 2, weak current
Electric current accurate transformation is voltage signal by circuit, and weak voltage signals is amplified, amplification factor are as follows:
As it will be easily appreciated by one skilled in the art that the foregoing is merely illustrative of the preferred embodiments of the present invention, not to
The limitation present invention, any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should all include
Within protection scope of the present invention.
Claims (4)
1. a kind of weak current circuit of nitrogen oxide sensor characterized by comprising sequentially connected Current Voltage conversion
Circuit, differential low-pass filter and instrumentation amplifier；
The current-to-voltage converting circuit, the current-to-voltage converting circuit are constituted by accessing sampling resistor in signal circuit
Current signal for acquiring nitrogen oxide sensor is converted to N times of voltage signal；The voltage signal is low by the difference
Bandpass filter export after accurately and effectively amplifying by the instrumentation amplifier again after filtering out High-frequency Interference；Wherein N
Value is equal to the resistance value size of the sampling resistor.
2. weak current circuit as described in claim 1, which is characterized in that the resistance value size of the sampling resistor is 80
Ω。
3. weak current circuit as claimed in claim 1 or 2, which is characterized in that the differential filter circuit includes: electricity
Hinder R1a, resistance R1b, capacitor C1a, capacitor C1b and capacitor C2；
The capacitor C1a, the capacitor C2 and the capacitor C1b are sequentially connected in series, the non-series connection end of the capacitor C1a
The series connection end of ground connection, the non-series connection end ground connection of the capacitor C1b, the capacitor C1a and the capacitor C2 are as institute
State the output cathode of differential filter circuit, the series connection end of the capacitor C1b and the capacitor C2 are as the differential filtering
The output negative pole of circuit；
One end of the resistance R1a as the differential filter circuit input anode, the other end of the resistance R1a with it is described
Capacitor C1a is connected with the series connection end of the capacitor C2；One end of the resistance R1b is as the defeated of the differential filter circuit
Enter cathode, the other end of the resistance R1b is connect with the series connection end of the capacitor C1b and the capacitor C2.
4. weak current circuit as described in any one of claims 1-3, which is characterized in that the instrumentation amplifier
It include: the first amplifier A1, the second amplifier A2, third amplifier A3, resistance R3, resistance R4, resistance R5, resistance R6, resistance R7, resistance
R8 and resistance R9；
Input anode of the normal phase input end of first amplifier A1 as the instrumentation amplifier, the reverse phase of the first amplifier A1
Input terminal is connected to the normal phase input end of the second amplifier A2 by resistance R3, and the inverting input terminal of the second amplifier A2 is as the instrument
The input cathode of table operational amplifier, the inverting input terminal of the first amplifier A1 also pass through resistance R4 and are connected to the first amplifier A1's
Output end, the normal phase input end of the second amplifier A2 are connected to the output end of the second amplifier A2 by resistance R5；
The output end of first amplifier A1 passes through the output that the resistance R6 being sequentially connected in series and resistance R8 is connected to third amplifier A3
The series connection end of end, resistance R6 and resistance R8 are connected to the normal phase input end of third amplifier A3；
The output end of second amplifier A2 passes through the resistance R7 being sequentially connected in series and resistance R9 ground connection；The string of resistance R7 and resistance R9
Connection connecting pin is connected to the inverting input terminal of third amplifier A3；
Output end of the output end of third amplifier A3 as the instrumentation amplifier.
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| CN201810836245.6A CN109239432A (en) | 2018-07-26 | 2018-07-26 | A kind of weak current circuit of nitrogen oxide sensor |
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| CN201810836245.6A CN109239432A (en) | 2018-07-26 | 2018-07-26 | A kind of weak current circuit of nitrogen oxide sensor |
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| CN109709151A (en) * | 2019-01-30 | 2019-05-03 | 南通大学 | A kind of thin dielectric film electrical properties measuring system |
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| CN112630516A (en) * | 2020-12-05 | 2021-04-09 | 西安翔腾微电子科技有限公司 | High-precision sensor current signal sampling method and circuit |
| CN112834804A (en) * | 2020-12-30 | 2021-05-25 | 成都杰启科电科技有限公司 | Low-cost high-precision current acquisition sensor and control method thereof |
| CN113428096A (en) * | 2021-08-27 | 2021-09-24 | 武汉元丰汽车电控系统股份有限公司 | Data acquisition card, apparatus and method |
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|---|---|---|---|---|
| CN109709151A (en) * | 2019-01-30 | 2019-05-03 | 南通大学 | A kind of thin dielectric film electrical properties measuring system |
| CN111446936A (en) * | 2020-05-14 | 2020-07-24 | 山东恒德智能装备科技有限公司 | Instrument circuit and ship instrument adopting same |
| CN111446936B (en) * | 2020-05-14 | 2023-08-25 | 山东恒力电机有限公司 | Instrument circuit and ship instrument adopting same |
| CN111740759B (en) * | 2020-06-11 | 2021-08-10 | 泰宇建筑工程技术咨询有限公司 | Building construction information transmission system based on Internet of things |
| CN111740759A (en) * | 2020-06-11 | 2020-10-02 | 包九月 | Building construction information transmission system based on Internet of things |
| CN112505536A (en) * | 2020-11-13 | 2021-03-16 | 上海金智晟东电力科技有限公司 | Weak signal anti-interference measurement method |
| CN112630516A (en) * | 2020-12-05 | 2021-04-09 | 西安翔腾微电子科技有限公司 | High-precision sensor current signal sampling method and circuit |
| CN112834804A (en) * | 2020-12-30 | 2021-05-25 | 成都杰启科电科技有限公司 | Low-cost high-precision current acquisition sensor and control method thereof |
| CN113899940A (en) * | 2021-08-24 | 2022-01-07 | 北京京医合符医药科技发展有限公司 | Acquisition and test circuit system for narrow pulse current |
| CN113428096A (en) * | 2021-08-27 | 2021-09-24 | 武汉元丰汽车电控系统股份有限公司 | Data acquisition card, apparatus and method |
| CN114640349A (en) * | 2022-05-12 | 2022-06-17 | 苏州联讯仪器有限公司 | Differential signal sampling circuit, differential signal sampling method and differential signal sampling device |
| CN116165420A (en) * | 2023-04-20 | 2023-05-26 | 杭州瑞盟科技股份有限公司 | Current detection circuit and device |
| CN116165420B (en) * | 2023-04-20 | 2023-10-03 | 杭州瑞盟科技股份有限公司 | Current detection circuit and device |
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Application publication date: 20190118 |
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