CN102507997A - Measuring circuit - Google Patents

Measuring circuit Download PDF

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Publication number
CN102507997A
CN102507997A CN2011103763307A CN201110376330A CN102507997A CN 102507997 A CN102507997 A CN 102507997A CN 2011103763307 A CN2011103763307 A CN 2011103763307A CN 201110376330 A CN201110376330 A CN 201110376330A CN 102507997 A CN102507997 A CN 102507997A
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China
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amplifier
analog
digital
signal
bipolarity
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CN2011103763307A
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Chinese (zh)
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许春香
张亦兰
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许春香
张亦兰
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Priority to CN2011103763307A priority Critical patent/CN102507997A/en
Publication of CN102507997A publication Critical patent/CN102507997A/en

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Abstract

The invention relates to a measuring circuit which consists of a primary inverting amplifier, a multistage gear amplifier, a multi-way electronic selective switch, an analog to digital converter, an embedded processing module, a testing voltage driving amplifier and the like, wherein the primary inverting amplifier consists of a resistor to be measured, a feedback resistor and an amplifier. After being added behind the end of the resistor to be measured of the primary inverting amplifier, a testing voltage passes through the multistage gear amplifier and is output by selecting the optimal gear amplifier to carry out analog to digital conversion so as to obtain testing data. The measuring circuit completely solves the problem of low accuracy of a dynamic measurement result and the problem of low measuring speed. The comprehensive measuring speed can achieve the range of less than 1ms. When a begohm sensor resistor is measured, only a precision resistor with a common resistance value is required, so that the difficulty of precision reference resistor is completely solved. The problem of nondeterminacy of voltage measurement on a sensor is solved and before and after reaction, the voltage added on the sensor is constant. Therefore, according to the measuring circuit, the requirements of modern micro/nano sensors on research and measurement are directly met and undoubtedly, the measuring circuit has far-reaching significance for promoting the research on the nano sensor and the Internet of things.

Description

A kind of metering circuit

Technical field

The present invention relates to rechargeable battery and management system thereof.

Background technology

Alcohol, CO, H 2The sensor of employing traditional handicrafts such as various gas sensors such as S, Temperature Humidity Sensor preparations is because sensitivity low (generally having only about 10), response speed slow (general 10-60 second); The various high-performance sensors that just are being used micro Nano material development replace with high sensitivity (up to 100,000), the unrivaled superior characteristics such as response speed (less than 10ms) that are exceedingly fast; Especially developing rapidly of modern technology of Internet of things; These Internet of Things front end novel sensor spares are received much concern; Demand heightens; Scientific research institutions at different levels develop, improve various kinds of sensors one after another, yet they but are to use traditional sensor measurement instrument to measure, analyze, and these instruments can not adapt to the characteristics of modern micro-nano sensor.

Traditional sensor measurement principle is to take the electric resistance partial pressure measuring principle, and promptly the sensor dividing potential drop of connecting with reference resistance is come the dead reckoning sensor resistance value through measuring partial pressure value.For example; Regular higher educational institutions's electrical category planning teaching material " detecting and switch technology " third edition China Machine Press (book number ISBN 7-111-03106-7); Chapter 8, the second solar term dependent sensor the 5th trifle basic test circuit (217 pages); Its measuring principle figure is as shown in Figure 3 to be exactly this partial pressure type measuring principle, can be through the resistance R s=UcR of formula calculating sensor QM-N5 from figure L/ U RL-R L(R in the formula LBe reference resistance, Uc is the test voltage source, U RLBe sampling voltage).And for example; Gansu science journal " the detection technique research of semiconductor gas sensor and array thereof " (2009), instrumental technique and sensor " based on the high resistant gas sensor test circuit of ARM " papers such as (2006); " the HW-C30A gas sensor test appearance " that Han Wei electronics corporation of Henan listed company produces also all takes this partial pressure type principle to measure.The measurement of this mode causes following several big problem, and causes the maximum error of measurement result:

The one, the dynamic measurement results precision is low; The result of dividing potential drop directly causes the precision of A/D conversion to reduce by 50%, and present micro-nano transducer sensitivity reached thousands of even tens thousand of times, and the measurement of this mode causes turning round and look under the so big dynamic amplitude of oscillation situation head and ignores tail; As measuring error is 1% before reacting; If the then reacted measuring error of reaction sensitivity 100 is just up to 1%*100=100%, so dynamic measurement precision is very low, well below the precision of the full scale of institute's nominal;

The 2nd, the resistance value scope of micro-nano sensor is extremely wide; Greatly to more than the begohm; Measure the accurate reference resistance that to select gigabit with this dividing potential drop mode; And the scope of conventional precision resistance is limited to below 2 megaohms, and very expensive material and special process making can not make or will be adopted to the precision resistance of this big resistance in fact, so can't realize measuring;

The 3rd, the uncertainty of sensor measurement voltage, and need clear and definite test voltage when micro-nano sensor research and test that is to say that if the actual voltage that is added on the sensor is a Dynamic Uncertain value, rather than 5V when using the 5V voltage measurement.Can know from Fig. 3, can derive the voltage U s=Uc*Rs/ (R on the sensor L+ Rs), the voltage U s that obviously is added on the sensor can change along with the variation before and after the sensor resistance reaction significantly, and therefore, the result who utilizes sort circuit to measure will directly mislead the result of study and the direction of micro-nano sensor experiment.

In addition, the traditional sensors surveying instrument takes manual shifting to solve the measurement range problem mostly, and obviously manual shifting can't solve the fast-changing measurement gearshift when reaction of sensor electrical resistance on a large scale and require (because reaction velocity is very fast); Industry is also taked self-shifting once in a while; The principle of gearshift generally is to adopt relay to switch accurate reference resistance (is to lower precision because it has conducting resistance without electronic switch); The intrinsic responsiveness of relay is generally about 10ms; If there are 8 grades, then possibly need examination survey 8 times, last the gear that 8*10ms=80ms just can seek needs, limited shift speed.In fact will catch up with the reaction velocity of micro-nano sensor 10ms, measuring speed should just can reflect the details of its variation at 1ms at least.

Sensor and control signal are measured general very low frequency signal and direct current signal is measured, and therefore, the zero point of metering circuit and drifting problem thereof also become a critical problem, and the method for taking usually is manual setting.How effectively, practicably the zero point and the drifting problem thereof that solve at present metering circuit, amplifier are difficult problems.

By on can know that existing measuring technique does not reach the research requirement of modern micro-nano sensor far away.

In addition, sensor or other circuit, device usually need be measured small voltage and Weak current signal, and they need the measuring basis problem of dynamic measurement precision problem, small voltage or electric current equally in measurement.

The present invention is devoted to develop the gordian technique that is applicable to modern micro-nano sensor measurement instrument---modern micro-nano sensor measuring circuit.

Summary of the invention

In view of above-mentioned, the present invention provides a kind of parallel quick gear, measures reasonable, accurate, the reliable a kind of metering circuit of result.

A kind of metering circuit is characterized in that:

Comprise by testing resistance Rs, feedback resistance Rf, amplifier AR1 and form first order inverting amplifier; The end of said testing resistance Rs and the end of said feedback resistance Rf are connected to the inverting input of said amplifier AR1, and the other end of said feedback resistance Rf is connected to the output terminal of said amplifier AR1;

Also comprise the gear amplifier AR2 that some gain per stages increase successively, AR3 ..., ARn and multichannel electronic selection switch M13; The output terminal of said amplifier AR1 is first grade output signal Vo1, directly or indirectly is connected to said gear amplifier AR2 at different levels, AR3 ...; The input end of ARn, and said gear amplifier AR2 at different levels, AR3; ..., the output terminal of ARn be output as successively second grade, third gear ... the output signal Vo1 of n shelves, Vo2; Vo3 ... Von, the multi-channel input selection that is connected respectively to said multichannel electronic selection switch M13 again is output as a drive test and gets bipolarity simulating signal VP;

Said gear amplifier AR2 amplifies on the basis of said amplifier AR1 and enlargement factor is said second grade of ratio with said first grade full grade of resistance value again; Said gear amplifier AR3 amplifies on the basis of said gear amplifier AR2 and enlargement factor is said third gear and the ratio of said second grade full grade of resistance value again, and all the other by that analogy;

Also comprise bipolarity analog to digital converter M12, the drive test that its input end is connected to the selection output of said multichannel electronic selection switch M13 gets bipolarity simulating signal VP, and is converted into and records digital signal;

Also comprise embedded processing module M11, the selection control end that both had been connected to said multichannel electronic selection switch M13 is to realize that described selection is output as a drive test and gets bipolarity simulating signal VP; Be connected to said bipolarity analog to digital converter M12 control end again and obtain the said digital signal that records;

Also comprise one by the first digital to analog converter M16 and the automatic back bias circuit at zero point that amplifier reverse bias circuit M17 forms; Said embedded processing module M11 connects the control line of the said first digital to analog converter M16; The said first digital to analog converter M16 analog output is connected to said amplifier reverse bias circuit M17 input end; Offset digital signal and convert bipolarity into zero point by said embedded processing module M11 output and offset simulating signal zero point, join said gear amplifier AR1, AR2 through said amplifier reverse bias circuit M17 again by the said first digital to analog converter M16; AR3; ..., in the one or more amplifier input terminal among the ARn, to offset the zero point of said amplifier;

Also comprise the second digital to analog converter M15 and test voltage driving amplifier M16; The said second digital to analog converter M15 control end is connected to said embedded processing module M11; Convert the digital signal of the test voltage of said embedded processing module M11 output into analog voltage signal; The said second digital to analog converter M15 analog output is connected to said test voltage driving amplifier M16 input end; Said test voltage driving amplifier M16 output terminal is exported test voltage signal Vt, and is connected to the other end of said testing resistance Rs;

Said bipolarity analog to digital converter M12 is a single-chip bipolarity analog to digital converter; Perhaps form by an analog inverter, a SS and a unipolarity analog to digital converter; Said analog inverter is connected to a described drive test and gets bipolarity simulating signal VP; Its output terminal is exported a drive test must simulate inversion signal VN; Said SS is controlled by said embedded processing module M11, and timesharing is selected saidly to record bipolarity simulating signal VP and to record simulation inversion signal VN and deliver to said unipolarity analog to digital converter, being the said digital signal that records with the bipolarity analog signal conversion.

Adopt above-mentioned metering circuit provided by the invention, have the significant advantage of following ten minutes:

(1) fast automatic gearshift has thoroughly solved low problem of dynamic measurement results precision and the slow problem of measuring speed, and composite measurement speed can reach in the 1ms, can reach the requirement of modern micro-nano sensor super big dynamic range, ultrafast response speed fully;

Do not need the high value precision resistance when (2) measuring big supreme begohm sensor resistance yet, thoroughly solve an accurate reference resistance difficult problem;

(3) solved the uncertain problem of sensor measurement voltage, the voltage that in measurement, is added on the sensor before and after the reaction is constant all the time.

(4) through automatic suppressed zero technology with zero point the automatic back bias technology thoroughly solved the zero point of metering circuit and the difficult problem of drifting about thereof.

(5) above advantage, the research and the measurement requirement of directly satisfied modern rice sensor, this has profound significance to the research that promotes modern nano-sensor and Internet of Things undoubtedly.

(6) metering circuit of the present invention not only is used for the resistance measurement with upper sensor; And can be used for the measurement of other type of electrical resistance; The measurement of especially big resistance resistance also can be owing to the measurement (this moment, test voltage need not to add) of Weak current and small voltage.

Description of drawings

Fig. 1 is a circuit composition diagram of the present invention.

Fig. 2 is the circuit diagram of a practical implementation case of the present invention.

Fig. 3 is the traditional measurement circuit diagram.

Embodiment

Fig. 1 is a circuit composition diagram of the present invention; Comprise by testing resistance Rs, feedback resistance Rf, amplifier AR1 and form first order inverting amplifier; The end of said testing resistance Rs and the end of said feedback resistance Rf are connected to the inverting input of said amplifier AR1, and the other end of said feedback resistance Rf is connected to the output terminal of said amplifier AR1.

Input test voltage is Vt, then first grade output signal

Vo1=-Vt*Rf/Rs

Can know the testing resistance that records through first grade

Rs=Rf*(-Vt/Vo1)

Here testing resistance is exactly the resistance of sensor to be measured.It is the said digital signal that records that Vo1 will obtain digital quantity through following bipolarity analog to digital converter, and Vt is the analog quantity that is provided with through the test voltage digital signal, and Rf is a known quantity, so can calculate the resistance value Rs of sensor.

Also comprise the gear amplifier AR2 that some gain per stages increase successively, AR3 ..., ARn and multichannel electronic selection switch M13; The output terminal of said amplifier AR1 is first grade output signal Vo1, directly or indirectly is connected to said gear amplifier AR2 at different levels, AR3 ...; The input end of ARn, and said gear amplifier AR2 at different levels, AR3; ..., the output terminal of ARn be output as successively second grade, third gear ... the output signal Vo1 of n shelves, Vo2; Vo3 ... Von, the multi-channel input selection that is connected respectively to said multichannel electronic selection switch M13 again is output as a drive test and gets bipolarity simulating signal VP.

Said gear amplifier AR2 amplifies on the basis of said amplifier AR1 and enlargement factor is said second grade of ratio with said first grade full grade of resistance value again; Said gear amplifier AR3 amplifies on the basis of said gear amplifier AR2 and enlargement factor is said third gear and the ratio of said second grade full grade of resistance value again, and all the other by that analogy.One of scheme that satisfies this regular gear amplifier is that amplifiers at different levels are connected successively, also can divide into groups series connection and parallel connection (seeing following specific embodiment).

Usually the ratio of each gear is certain, is made as A, and then n shelves output voltage does

Von=A (n-1)*Vo1=A (n-1)*(-Vt Rf/Rs)

If the testing resistance that the n shelves calculate is Rs (n), then

Rs(n)=A (n-1)*Rf*(-Vt/Vo1)

Also comprise bipolarity analog to digital converter M12, the drive test that its input end is connected to the selection output of said multichannel electronic selection switch M13 gets bipolarity simulating signal VP, and is converted into and records digital signal.In fact VP equals the output signal Vo1 of above gear amplifiers at different levels, Vo2, and Vo3 ... Von.

Also comprise embedded processing module M11, the selection control end that both had been connected to said multichannel electronic selection switch M13 is to realize that described selection is output as a drive test and gets bipolarity simulating signal VP; Be connected to said bipolarity analog to digital converter M12 control end again and obtain the said digital signal that records.

The bipolarity simulating signal VP has here comprised useful measuring-signal and useless zero signal, and the zero signal intrinsic characteristic that is amplifier, just must have, have negative, promptly is ambipolar, and is difficult in advance know.Automatically the suppressed zero technology is that the present invention improves and guarantees one of gordian technique of dynamic measurement precision.Circuit structure of the present invention provides all conditions of automatic suppressed zero; (Vt=0) measures the output valve Vo1~Von of each gear before promptly measuring; As zero point value record on record; The value at zero point that when formal the measurement, measured value is deducted (value at zero point for the useful signal anti-phase is a negative value, is actually the absolute value that adds zero point) this respective notch gets final product.

Also comprise one by the first digital to analog converter M16 and the automatic back bias circuit at zero point that amplifier reverse bias circuit M17 forms; Said embedded processing module M11 connects the control line of the said first digital to analog converter M 16; The said first digital to analog converter M, 16 analog outputs are connected to said amplifier reverse bias circuit M17 input end; Offset digital signal and convert bipolarity into zero point by said embedded processing module M11 output and offset simulating signal zero point, join said gear amplifier AR1, AR2 through said amplifier reverse bias circuit M17 again by the said first digital to analog converter M16; AR3; ..., in the one or more amplifier input terminal among the ARn, to offset the zero point of said amplifier.

Aforesaid amplifier inherent characteristic---zero point; Since can be from NMO correction; Why also need automatic back bias circuit at this at zero point? Reason is after being amplified step by step the zero point of the amplifier selected, possibly can compare mutually with a full shelves output voltage even surpasses a full shelves magnitude of voltage, therefore; Be necessary automatic back bias circuit at zero point to be set in one or several gear amplifier input terminal of back; In case and certain grade of gear amplifier adds zero-bias, then follow-up gear amplifier has all also added zero-bias in the lump, and zero-bias is to amplify according to the amplification quantity of these grades.Zero point, the course of work of automatic back bias circuit was: the common state of voltage Vz that zero point, the automatic back bias circuit was added is 0 voltage; And offset the half the amount of digital signal (increase and decrease can realize that the zero bias-voltage of exporting is the bipolarity degree of amplitude modulation on this basis) zero point of usually corresponding this first digital to analog converter M16; Gather the output voltage of final stage gear amplifier this moment; Offset digital signal and output zero point according to the reverse adjustment of its value, and then measure, adjustment again, till the output voltage of final stage gear amplifier is near 0; Note the reverse biased digital quantity of this moment, in measuring process, be provided with and keep it constant.Here the output voltage of final stage gear amplifier does not need furnishing 0, because this very little value at zero point can be removed through aforesaid automatic suppressed zero.

Therefore, through above automatic zero adjustment and zero point the automatic back bias technology thoroughly solved metering circuit zero point and the drift difficult problem.

Also comprise the second digital to analog converter M15 and test voltage driving amplifier M16; The said second digital to analog converter M15 control end is connected to said embedded processing module M11; Convert the digital signal of the test voltage of said embedded processing module M11 output into analog voltage signal; The said second digital to analog converter M15 analog output is connected to said test voltage driving amplifier M16 input end; Said test voltage driving amplifier M16 output terminal is exported test voltage signal Vt, and is connected to the other end of said testing resistance Rs.

Need add this test voltage Vt at its two ends during sensor measurement; Just can reflect the variation of its characteristic, and from researching and analysing needs, this test voltage must be constant in measuring process; Can also be provided with artificially, with observation analysis response characteristic under different test voltages.The test voltage Vt of above circuit is controlled with digital form by flush bonding module M11, so the user can be provided with arbitrarily as required.

Certainly, then Vt need be provided when metering circuit of the present invention is used for measuring voltage and electric current, but import voltage to be measured or current signal at this end of resistance R s.

Said bipolarity analog to digital converter M12 is a single-chip bipolarity analog to digital converter; Perhaps form by an analog inverter, a SS and a unipolarity analog to digital converter; Said analog inverter is connected to a described drive test and gets bipolarity simulating signal VP; Its output terminal is exported a drive test must simulate inversion signal VN; Said SS is controlled by said embedded processing module M11, and timesharing is selected saidly to record bipolarity simulating signal VP and to record simulation inversion signal VN and deliver to said unipolarity analog to digital converter, being the said digital signal that records with the bipolarity analog signal conversion.

This bipolarity analog to digital converter of back is the loose mail assembling mode of single-chip bipolarity analog to digital converter; Mainly provide a kind of lower-cost bipolarity analog to digital converter scheme, because existing cost quick, single-chip bipolarity analog to digital converter is all higher.

Further specify the principle of accurate measurement below from actual angle.

Embedded processing module M11 collects the output signal Vo1 of gears at different levels through the work of the above circuit of control, Vo2, and Vo3 ... Von, the output signal of analyzing the best gear of selection then is to calculate testing resistance value Rs.If the set every grade of amplification quantity of preamble is A=2 3=8, establishing analog-to-digital converter resolution is 10, and the gear amplifier output voltage is in maximal value in the time of then full grade, and corresponding testing resistance value is the minimum resistance of this grade, and the measuring resistance precision is 1/2 10≈ 0.1%, so need fall the one-level gear during the full shelves of voltage, also promptly selects the output of little gear amplifier to calculate the testing resistance value; And at this gear amplifier output voltage during for the 1/A=1/8 of full shelves threshold voltage, the A=8 of corresponding testing resistance value resistance during for full shelves doubly, precise decreasing is 1/2 10-3≈ 0.78%, descends for guaranteeing that precision is unlikely again, and at this moment need being changed to more, high tap position amplifies the back measurement with signal.In other words; The purpose of changing gear with upper type be in order to ensure precision between 0.1%~0.78%; And owing to be that each gear amplifier is exported simultaneously; We need only the gear output that can in very short time, obtain a best through aforementioned analog to digital converter fast, guarantee that promptly precision is between 0.1%~0.78%.We can select analog to digital converter faster, are 50KBPS (this speed is the medium speed in the A/D converter) like slewing rate, and then above at most through 8 A/D conversions, needing the time is 8/50K=0.16mS.Because gear amplifiers at different levels are stably to amplify (the parameter device that does not switch its input signal or amplifier); Therefore the speed of signal only depends on the speed of amplifier itself; If we select slower amplifier; For example postponing is 20 μ S, and then 8 grades of amplifiers are 8*20 μ S=0.16mS.Then measuring at interval, minimum is 0.16mS+0.16mS=0.32mS.Above data all are very conservative data, and therefore, we are easy to accomplish to measure at interval measure less than the high speed of 1ms.

In addition, first order amplifier Rf gets 100 Europe, and test voltage is conventional Vt=5V, and full shelves voltage Vo1=-5V according to above gear, can calculate:

Resistance value Rs* (8)=87*Rf* during the full shelves of maximum gear (Vt/Vo1)=209M Europe (this moment, the resolution precision 0.1%).

Then resolution is that precision is testing resistance value Rs=8*209M Europe=1618M Europe=1.618G Europe of measuring in 0.78% o'clock.Therefore the present invention could measure high-precision super large resistance value easily! Improve precision, only needing the resolution of raising A/D converter (analog to digital converter or bipolarity analog to digital converter) is that figure place gets final product.

Influence the resistance of decision amplification quantity in also having of the above measuring accuracy gear amplifiers at different levels; The precision of these resistance can select 0.01%; And can (promptly changing testing resistance into accurate resistance measures through the calibration of adjustable resistance or software coefficient; So the measuring error that this part precision causes can be eliminated the calibration factor of the ratio of this accurate resistance and the value of measuring when measuring later on).But above because the precision problem that A/D converter causes is impossible eliminate, can only be through improving the resolution of A/D converter.

In addition; In fact the precision of test voltage does not influence the precision of above resistance measurement; As long as the reference voltage that the sampling of the digital to analog converter of analog to digital converter (or bipolarity analog to digital converter) and test voltage is identical; Test voltage all is directly proportional with this reference voltage with the measuring voltage of above amplifier output, so the influence that digital quantity has just in time been offset the reference voltage deviation when calculating.

Fig. 2 is the circuit diagram of a practical implementation case of the present invention; With flush bonding processor---single-chip microcomputer U1 is a processing enter; U1 selects STC12C5A60S2, has 10 unipolarity analog to digital converters of multichannel ADC, 2 way weighted-voltage D/A converter PWM (DAC); General controls mouth lines etc. are the reference voltage of working power voltage and ADC, PWM (DAC) with+5V.Convenient for principle analysis, we suppose that still the second level and later gear amplifier gain all are set at A=8.

First order gear amplifier is formed inverting amplifier by testing resistance Rs, feedback resistance Rf, operational amplifier A R1; N level gear amplifier is formed in-phase amplifier by stake resistance Rn1, feedback resistance Rn2, operational amplifier A Rn; The output signal is Von (n=2; 3 ... 8), as shown in Figure 2; The time-delay synergistic effect when lowering the amplifier cascade and the accumulative total effect of amplification quantity precision (the more accumulative total of amplifier progression precision are low more); According to one group of every two-stage be concatenated into after the input side by side next group (why can not amplify as one-level separately by each grade, be because the single-stage amplification quantity when too big amplifier be difficult to steady operation), therefore the amplification quantity of every group high one-level amplifier should for low one-level amplification quantity square times.Like this,

The time-delay of a gear amplifier of signal lag=5* of high tap position amplifier

The precision of the precision of * resistance=11* resistance of the amplification quantity precision of high tap position amplifier=(1+4*2+2*1)

(having comprised the influence of precision of 2 resistance of analog inverter)

If every grade of delay is 20 μ S, the signal lag of then high tap position amplifier is 100 μ S.

(Rf, Rn1, amplification quantity precision=0.11% of the high tap position amplifier of 0.01% of accuracy selection Rn2) if the resistance that the amplifier amplification quantity is relevant.

Analog-to-digital converter resolution is 10 in the present case, promptly 0.1%, and resultnat accuracy therefore basic and gear amplifier amplification quantity is complementary.In case selected analog-to-digital converter resolution, the full accuracy of system confirm that at this point then can remove its error through calibration as for the precision of above amplifier amplification quantity, the way preamble is explained.

In addition and since more than amplification quantity at different levels little, be 8 or 64, therefore; For instance, if establish resistance R _ f=100 Europe, Rn1=1K Europe (n=2~8); R22=R42=R62=R82=8K Europe then, R32=R52=R72=64K Europe, these resistance are all in the scope that 0.01% precision resistance is produced easily.Before explain that the 8th grade of gear amplifier measuring can be the testing resistance value Rs=1.618G Europe of measuring in precision at 0.78% o'clock.Like this, the precision of measurement super large resistance need not depend on the super large precision resistance.

U2 is one 8 and selects an analog selection switch; Adopt CD4051B, by the mouth line P1.2 of single-chip microcomputer U1, P1.3; It is the ADC0 that a bipolarity simulating signal VP delivers to single-chip microcomputer U1 that the output signal Vo1~Vo8 of each gear amplifier is selected in P1.4 control timesharing; Also deliver to simultaneously the analog inverter of being made up of input resistance R1, feedback resistance R2 and operational amplifier A R9, it is output as and records the ADC1 that simulation inversion signal VN delivers to single-chip microcomputer U1, selects VP or VN to be input to built-in ADC through the built-in SS of single-chip microcomputer; Form the bipolarity analog to digital converter, being the said digital signal that records with the bipolarity analog signal conversion.Wherein R3, R4 play the current-limiting protection effect.

Single-chip microcomputer has been formed second digital to analog converter through built-in pulse width modulator PWM1 output and through R8, C3 low-pass filter; Pass through then by resistance R 9; The test voltage driving amplifier output test voltage signal Vt that R10 and operational amplifier A R10 form is added in testing resistance Rs left end.

Simultaneously, in order to remove the excessive zero-point voltage of possibility, also added automatic back bias circuit at zero point in the present embodiment; Single-chip microcomputer exported and passed through R11, C4 composition through built-in pulse width modulator PWM0 low-pass filter has constituted first digital to analog converter, through R5, and R6; R7 forms amplifier reverse bias circuit; The anti-phase input resistance R41 that joins fourth speed position amplifier sentences input zero bias-voltage Vz, and follow-up gear also will obtain this zero bias-voltage, and amplify step by step.Because need the zero bias-voltage Vz of input very little, below millivolt, and PWM output intermediate value is+5V/2=+2.5V; R5 connects-5V, and amplitude is all very big, so R7 can be very little; Little of comparing with R41 and can ignore, thus the amplification quantity of the measuring-signal of fourth speed position amplifier do not influenced.Its at zero point the automatic back bias circuit principle of work with aforesaid identical.Below be zero concrete partially computing formula:

The zero bias-voltage Vz that zero inclined to one side circuit adds:

Vz=(5/(R6+R11)-5/R5)/(1/(R6+R11)+1/R5+1/R7)

Outputs at different levels behind adding zero bias-voltage:

Vo4=8 3*(-Vt*Rf/Rs)-Vz*R42/R41=8 3*(-Vt*Rf/Rs)-8 0*Vz*7

Vo5=8 4*(-Vt*Rf/Rs)-8 1*Vz*7

Vo6=8 5*(-Vt*Rf/Rs)-8 2*Vz*7

Vo7=8 6*(-Vt*Rf/Rs)-8 3*Vz*7

Vo8=8 7*(-Vt*Rf/Rs)-8 4*Vz*7

In this example, Vo1~Vo3 is irrelevant with zero bias-voltage Vz.

In addition, metering circuit of the present invention not only is used for the resistance measurement with upper sensor, and can be used for the measurement of other type of electrical resistance, the measurement of especially big resistance resistance.Also can be used for the measurement (this moment, test voltage need not to add) of Weak current and small voltage, get final product at Rs left end input voltage or electric current this moment.Rs possibly need to select the value different with resistance measurement with the Rf value when small voltage or Weak current were measured certainly, and wherein Rs adopts fixed resistance to replace.

When measuring Weak current, can select to import the amplifier of leakage current below the pA level, can measure the above Weak current of pA level, measuring method identical with above resistance except test voltage not.

When measuring small voltage; Can select the amplifier of input offset voltage below μ V level; And Rs and Rf can select bigger precision resistance such as 100K~2000K Europe, can measure the above small voltage of μ V level, measuring method identical with above resistance except test voltage not.

Obviously, those skilled in the art can carry out various changes and modification to the present invention and not break away from the spirit and scope of the present invention.Like this, belong within the scope of claim of the present invention and equivalent technologies thereof if of the present invention these are revised with modification, then the present invention also is intended to comprise these changes and modification interior.

Although described the preferred embodiments of the present invention, in a single day those skilled in the art get the basic inventive concept could of cicada, then can make other change and modification to these embodiment.So accompanying claims is intended to be interpreted as all changes and the modification that comprises preferred embodiment and fall into the scope of the invention.

The above is merely preferred embodiment of the present invention, and is in order to restriction the present invention, not all within spirit of the present invention and principle, any modification of being made, is equal to replacement, improvement etc., all should be included within the scope that the present invention protects.

Claims (12)

1. metering circuit is characterized in that:
Comprise by testing resistance (Rs), feedback resistance (Rf), amplifier (AR1) and form first order inverting amplifier; One end of one end of said testing resistance (Rs) and said feedback resistance (Rf) is connected to the inverting input of said amplifier (AR1), and the other end of said feedback resistance (Rf) is connected to the output terminal of said amplifier (AR1);
Also comprise the gear amplifier that some gain per stages increase successively (AR2, AR3 ..., ARn) with multichannel electronic selection switch (M13); The output terminal of said amplifier (AR1) is first grade an output signal (Vo1), directly or indirectly be connected to said gear amplifier at different levels (AR2, AR3 ...; ARn) input end, and said gear amplifier (AR2, AR3 at different levels; ..., output terminal ARn) be output as successively second grade, third gear ... the output signal of n shelves (Vo1, Vo2; Vo3 ... Von), the multi-channel input selection that is connected respectively to said multichannel electronic selection switch (M13) again is output as a drive test and gets bipolarity simulating signal (VP);
Said gear amplifier (AR2) is on the basis of said amplifier (AR1), to amplify and enlargement factor is said second grade of ratio with said first grade full grade of resistance value again; Said gear amplifier (AR3) is on the basis of said gear amplifier (AR2), to amplify and enlargement factor is said third gear and the ratio of said second grade full grade of resistance value again, and all the other by that analogy;
Also comprise bipolarity analog to digital converter (M12), the drive test that its input end is connected to the selection output of said multichannel electronic selection switch (M13) gets bipolarity simulating signal (VP), and is converted into and records digital signal;
Also comprise embedded processing module (M11), the selection control end that both had been connected to said multichannel electronic selection switch (M13) is to realize that described selection is output as a drive test and gets bipolarity simulating signal (VP); Be connected to said bipolarity analog to digital converter (M12) control end again and obtain the said digital signal that records.
2. a kind of metering circuit according to claim 1; It is characterized in that: also comprise an automatic back bias circuit at zero point of forming by first digital to analog converter (M16) and an amplifier reverse bias circuit (M17); Said embedded processing module (M11) connects the control line of said first digital to analog converter (M16); Said first digital to analog converter (M16) analog output is connected to said amplifier reverse bias circuit (M17) input end, is exported to offset digital signal and convert bipolarity into by said first digital to analog converter (M16) zero point by said embedded processing module (M11) and offsets simulating signal zero point, joins said gear amplifier (AR1 through said amplifier reverse bias circuit (M17) again; AR2; AR3 ..., in the one or more amplifier input terminal in ARn).
3. a kind of metering circuit according to claim 1; It is characterized in that: also comprise second digital to analog converter (M15) and test voltage driving amplifier (M16); Said second digital to analog converter (M15) control end is connected to said embedded processing module (M11); Convert the digital signal of the test voltage of said embedded processing module (M11) output into analog voltage signal; Said second digital to analog converter (M15) analog output is connected to said test voltage driving amplifier (M16) input end, and said test voltage driving amplifier (M16) output terminal is exported test voltage signal (Vt), and is connected to the other end of said testing resistance (Rs).
4. a kind of metering circuit according to claim 1 is characterized in that: said bipolarity analog to digital converter (M12) is a single-chip bipolarity analog to digital converter, is the said digital signal that records with the bipolarity analog signal conversion.
5. a kind of metering circuit according to claim 1; It is characterized in that: said bipolarity analog to digital converter (M12) is made up of an analog inverter, a SS and a unipolarity analog to digital converter; Said analog inverter is connected to a described drive test and gets bipolarity simulating signal (VP); Its output terminal is exported a drive test must simulate inversion signal (VN); Said SS is controlled by said embedded processing module M11, and timesharing is selected saidly to record bipolarity simulating signal (VP) and simulate inversion signal (VN) and deliver to said unipolarity analog to digital converter with recording, being the said digital signal that records with the bipolarity analog signal conversion.
6. a kind of metering circuit according to claim 1 is characterized in that: have claim 2 and 3 all technical characteristics that limit.
7. a kind of metering circuit according to claim 1 is characterized in that: have claim 2 and 4 all technical characteristic that limits.
8. a kind of metering circuit according to claim 1 is characterized in that: have claim 3 and 4 all technical characteristic that limits.
9. a kind of metering circuit according to claim 1 is characterized in that: have claim 2,3 and 4 all technical characteristics that limit.
10. a kind of metering circuit according to claim 1 is characterized in that: have claim 2 and 5 all technical characteristic that limits.
11. a kind of metering circuit according to claim 1 is characterized in that: have claim 3 and 5 all technical characteristic that limits.
12. a kind of metering circuit according to claim 1 is characterized in that: have claim 2,3 and 5 all technical characteristics that limit.
CN2011103763307A 2011-11-10 2011-11-10 Measuring circuit CN102507997A (en)

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104779958A (en) * 2014-01-10 2015-07-15 亚德诺半导体集团 Amplifying system
CN105675995A (en) * 2016-02-01 2016-06-15 凯迈(洛阳)电子有限公司 Embedded multi-channel automatic resistance measurement module
CN106324331A (en) * 2015-06-30 2017-01-11 大唐半导体设计有限公司 Isolated power supply front-end voltage sampling method and device
CN109975731A (en) * 2018-12-28 2019-07-05 北京航天测控技术有限公司 A kind of measuring system based on real time calibration
CN110618309A (en) * 2019-09-20 2019-12-27 北京大学 Semiconductor detector leakage current measuring device and measuring method

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104779958A (en) * 2014-01-10 2015-07-15 亚德诺半导体集团 Amplifying system
CN104779958B (en) * 2014-01-10 2018-06-22 亚德诺半导体集团 amplification system
CN106324331A (en) * 2015-06-30 2017-01-11 大唐半导体设计有限公司 Isolated power supply front-end voltage sampling method and device
CN106324331B (en) * 2015-06-30 2019-03-12 大唐半导体设计有限公司 A kind of isolated power supply front voltage method of sampling and device
CN105675995A (en) * 2016-02-01 2016-06-15 凯迈(洛阳)电子有限公司 Embedded multi-channel automatic resistance measurement module
CN109975731A (en) * 2018-12-28 2019-07-05 北京航天测控技术有限公司 A kind of measuring system based on real time calibration
CN110618309A (en) * 2019-09-20 2019-12-27 北京大学 Semiconductor detector leakage current measuring device and measuring method

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Application publication date: 20120620