CN105527501B - A kind of micro capacitance method - Google Patents

A kind of micro capacitance method Download PDF

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Publication number
CN105527501B
CN105527501B CN201510894356.9A CN201510894356A CN105527501B CN 105527501 B CN105527501 B CN 105527501B CN 201510894356 A CN201510894356 A CN 201510894356A CN 105527501 B CN105527501 B CN 105527501B
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China
Prior art keywords
capacitance
testing
discharge time
voltage value
capacitor
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CN201510894356.9A
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Chinese (zh)
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CN105527501A (en
Inventor
谢念
何峰
寻骈臻
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中国电子科技集团公司第四十八研究所
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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01RMEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R27/00Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
    • G01R27/02Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
    • G01R27/26Measuring inductance or capacitance; Measuring quality factor, e.g. by using the resonance method; Measuring loss factor; Measuring dielectric constants ; Measuring impedance or related variables
    • G01R27/2605Measuring capacitance

Abstract

The present invention discloses a kind of micro capacitance method, the measurement method includes measured capacitance value, measured capacitance value are as follows: required discharge time when measurement testing capacitance and reference capacitance are discharged to second voltage value from the first voltage value respectively calculates the capacitance of testing capacitance according to the discharge time that the relationship and measurement of discharge time and capacitance obtain.The present invention is based on the relationships of discharge time and capacitance to measure capacitance, have realize it is easy to operate, required it is at low cost, small capacitance can be measured and do not limited by capacitance, while measurement efficiency and advantage with high accuracy.

Description

A kind of micro capacitance method

Technical field

The present invention relates to capacitance measuring technique field more particularly to a kind of micro capacitance methods.

Background technique

Characteristic of the capacitance sensor because of its small size and low-power consumption and in high precision etc., in industry and consumer production There is very extensive application in the multiple fields such as product.It is directed to the measurement of capacitor at present, common method has resonance method, oscillation Method, charge and discharge electrical method and ac-excited method etc., wherein resonance method and succusion are not suitable for being applied to survey the high-precision of small capacitance It measures in occasion, drift and temperature drift are larger when charge and discharge electrical method, thus the stability of system is limited;The ac-excited method response time is long, and It is not easy to practical application.Above-mentioned capacitance measurement method usually also needs to rely in addition to all having the limitation that can not respectively overcome Complicated circuit design, realization is complicated for operation, and capacitive measurement scales are fixed and are difficult to be extended, thus cannot achieve to various The measurement of size small capacitance.Circuit knot can be simplified to a certain extent even by the mode of capacitive digital converter chip Structure, but the price of usually such chip is high and using complicated, and performance and a variety of limitations are still remained to measurement capacitor itself.

Summary of the invention

The technical problem to be solved in the present invention is that, for technical problem of the existing technology, the present invention provides one Kind realize it is easy to operate, required it is at low cost, small capacitance can be measured and do not limited by capacitance, while measurement efficiency and precision High micro capacitance method.

In order to solve the above technical problems, technical solution proposed by the present invention are as follows:

A kind of micro capacitance method, the measurement method include measured capacitance value step, the measured capacitance value step Suddenly are as follows: required discharge time when measurement testing capacitance and reference capacitance are discharged to second voltage value from the first voltage value respectively, The capacitance of testing capacitance is calculated according to the discharge time that the relationship and measurement of discharge time and capacitance obtain.

As a further improvement of the present invention, the specific measuring process of the discharge time are as follows: successively by testing capacitance, ginseng It examines capacitor to be connected in same charging and discharging circuit, will be made after the capacitor charging to the first voltage value of access by the charging and discharging circuit The capacitor of the access starts to discharge, and record be discharged to second voltage value needed for discharge time, respectively measurement obtain it is to be measured Discharge time needed for capacitor, reference capacitance.

As a further improvement of the present invention: the charging and discharging circuit by pulse signal generator to the capacitor of access into Row charging makes the capacitor of access discharge by discharge resistance;The charging and discharging circuit records discharge time by time converter.

As a further improvement of the present invention: the measured capacitance value step further includes reference capacitance configuration step, specifically The capacitor of same quantitative levels is in as reference capacitance with testing capacitance for configuration.

As a further improvement of the present invention: the second voltage value is the first voltage value of designated ratio, wherein 0 < refer to Certainty ratio < 100%.

As a further improvement of the present invention, the capacitance of the testing capacitance with specific reference to reference capacitance capacitance, And the ratio calculation of discharge time obtains between testing capacitance and reference capacitance.

As a further improvement of the present invention: the capacitance of the testing capacitance is specifically calculated according to the following formula;

C = C0* μ/(μ+n)

Wherein C is the capacitance of testing capacitance, C0For the capacitance of reference capacitance, μ is testing capacitance from the first voltage value V0 It is discharged to second voltage value VtThe discharge time of Shi Suoxu, μ+n are reference capacitance from the first voltage value V0It is discharged to second voltage value VtThe discharge time of Shi Suoxu, wherein the discharge time between testing capacitance and reference capacitance is poor.

As a further improvement of the present invention, the measurement method further includes distributed capacitance removal step, specific steps Are as follows: successively using the distribution capacity of testing capacitance both ends conducting wire as target capacitance, mesh is calculated according to the measured capacitance value step The capacitance for marking capacitor obtains the distributed capacitance of testing capacitance both ends conducting wire, and is gone according to obtained distributed capacitance calculating Except the final capacitance of testing capacitance after distributed capacitance.

As a further improvement of the present invention: when the capacitance for calculating target capacitance, especially by by target capacitance The conducting wire at place end is connected in charging and discharging circuit, discharge time needed for measuring target capacitance.

As a further improvement of the present invention: the final capacitance of the testing capacitance is by the testing capacitance that is calculated The distributed capacitance that capacitance subtracts both ends conducting wire obtains.

Compared with the prior art, the advantages of the present invention are as follows:

1) micro capacitance method of the present invention, it is to be measured by measuring based on the characteristic between discharge time and capacitance Discharge time between capacitor and reference capacitance calculates the capacitance of testing capacitance, needs not rely on complicated circuit structure, Realize that easy to operate and measurement efficiency and precision are high, simultaneously because based on discharge time between reference capacitance and testing capacitance Comparison, thus the measurement of the very small small capacitance of capacitance may be implemented, and measurement range is unrestricted, the application of measurement Occasion is extensive;

2) micro capacitance method of the present invention, by successively connecing testing capacitance, reference capacitance when discharge time measures To in same charging and discharging circuit, the capacitor of access is carried out by identical charge and discharge process by charging and discharging circuit, can make to It surveys capacitor and reference capacitance is under same charge and discharge operating condition, so that discharge time and capacitance are established linear relationship, be based on Discharge time comparison in the discharge process can accurately calculate the capacitance of testing capacitance;

3) micro capacitance method of the present invention, when discharge time only needs measurement to be discharged to a certain proportion of supply voltage value The required time, without completing entire discharge process, compared with traditional measurement method needs to complete entire discharge process, Ke Yi great It is big to shorten time of measuring, effectively improve measurement efficiency;

4) in micro capacitance method of the present invention, by configuring the reference capacitance with the same order of magnitude of testing capacitance, by The comparison of discharge time determines the capacitance of testing capacitance between the capacitor of the same order of magnitude, can reduce gain offsets, thus Further increase the precision of capacitance measurement;Simultaneously by reference to the configuration of capacitor, the small electric to each quantitative levels may be implemented The measurement of appearance, is not limited by capacitance size;

5) micro capacitance method of the present invention, on the basis of measured capacitance value, by measuring testing capacitance two respectively The distributed capacitance at end can effectively eliminate distribution capacity pair in micro capacitance compared to more traditional resonance method, advocate approach etc. The influence of measurement result obtains the accurate capacitance of testing capacitance.

Detailed description of the invention

Fig. 1 is the implementation process schematic diagram of the present embodiment micro capacitance method.

Fig. 2 is the structural schematic diagram of charging and discharging circuit in the present embodiment.

Fig. 3 is the realization principle schematic diagram of the present embodiment micro capacitance method.

Fig. 4 is the discharge curve contrast schematic diagram of testing capacitance and reference capacitance in the present embodiment.

Fig. 5 is the principle schematic diagram of distribution capacity in testing capacitance.

Fig. 6 is the realization principle schematic diagram that the present embodiment micro capacitance method includes removal distribution capacity step.

Specific embodiment

Below in conjunction with Figure of description and specific preferred embodiment, the invention will be further described, but not therefore and It limits the scope of the invention.

As shown in Figure 1, the present embodiment micro capacitance method includes measured capacitance value step, measured capacitance value step Are as follows: required discharge time, root when measurement testing capacitance and reference capacitance are discharged to second voltage value from the first voltage value respectively The capacitance of testing capacitance is calculated according to the discharge time that the relationship and measurement of discharge time and capacitance obtain.

Since under identical operating condition, the discharge time length of capacitor is related to capacitance, i.e. discharge time is in capacitance Linear relationship, the present embodiment pass through measurement testing capacitance and reference capacitance based on the characteristic between discharge time and capacitance Between discharge time calculate the capacitance of testing capacitance, need not rely on complicated circuit structure, realize it is easy to operate and The efficiency and precision of measurement are high, simultaneously because based on reference capacitance compared with discharge time between testing capacitance, thus can To realize the measurement of the very small small capacitance of capacitance, and measurement range is unrestricted, and the application of measurement is extensive.

In the present embodiment, the specific measuring process of discharge time are as follows: testing capacitance, reference capacitance are successively connected to same fill In discharge loop, the capacitor of access will be made to start to discharge after the capacitor charging to the first voltage value of access by charging and discharging circuit, And record be discharged to second voltage value needed for discharge time, respectively measurement obtain testing capacitance, reference capacitance needed for electric discharge Time.By the way that successively testing capacitance, reference capacitance are connected in same charging and discharging circuit, by charging and discharging circuit by the capacitor of access Identical charge and discharge process is carried out, testing capacitance and reference capacitance can be made to be under same charge and discharge operating condition, thus will Discharge time and capacitance establish linear relationship, can accurately be calculated based on the discharge time comparison in the discharge process to be measured The capacitance of capacitor.

The present embodiment charging and discharging circuit is as shown in Fig. 2, include pulse signal generator, the testing capacitance of access or reference electricity Appearance and discharge resistance put the capacitor of access to the capacitor charging of access, by discharge resistance by pulse signal generator Electricity, structure is simple and stability is good.The present embodiment also sets up the discharge time in time converter record charging and discharging circuit, specifically Using High-precision time-to-digital converter, high-precision discharge time can be intuitively acquired.Testing capacitance and reference electricity When the discharge time measurement of appearance, successively testing capacitance, reference capacitance are accessed in charging and discharging circuit, so that being put with same Resistance connection composition Low-pass low-pass filter circuit;As shown in figure 3, pulse signal is generated by pulse signal generator, it will The capacitor charging accessed in charging and discharging circuit to the supply voltage of the first voltage value, then charging and discharging circuit by discharge resistance into Row electric discharge, required time is recorded by time-to-digit converter when being discharged to second voltage value, testing capacitance and reference electricity Hold respectively execute above-mentioned steps after i.e. can measure obtains corresponding discharge time, the discharge time obtained by measurement can calculate to Survey the capacitance of capacitor.

The electricity of capacitor and the voltage at its both ends are linear, are represented by Q=UC, and wherein Q is the electricity of capacitor, U For the voltage at capacitor both ends, C is capacitance, thus can determine corresponding electric capacitance change by voltage value.In the present embodiment, Second voltage value is the first voltage value of designated ratio, wherein 0 < designated ratio < 100%, can be configured according to actual needs, I.e. discharge time only needs measurement to be discharged to the time required when a certain proportion of supply voltage value, entirely discharges without completing Journey can greatly shorten time of measuring compared with traditional measurement method needs to complete entire discharge process, effectively improve measurement effect Rate.The present embodiment specifically takes 90%, that is, the discharge time measured be discharged to the first voltage value 90%(original capacitor electricity 90%) When the time required to, second voltage value specifically can also be configured according to actual needs.

In the present embodiment, measured capacitance value step further includes reference capacitance configuration step, specially configuration and testing capacitance Capacitor in same quantitative levels is as reference capacitance, if testing capacitance is pF grades, then pF grades of capacitors of corresponding selection are made For reference capacitance.Before testing capacitance measurement, can usually determine its quantitative levels (order of magnitude), the present embodiment by configure with to The reference capacitance for surveying the same order of magnitude of capacitor, determines testing capacitance by the comparison of discharge time between the capacitor of the same order of magnitude Capacitance can reduce gain offsets, to further increase the precision of capacitance measurement, while by reference to the configuration of capacitor, The measurement that the small capacitance to each quantitative levels may be implemented, is not limited by capacitance size, and testing capacitance is specifically as follows several Capacitor of the fF to tens nF.

In the present embodiment, the value of testing capacitance is with specific reference to the capacitance and testing capacitance of reference capacitance and with reference to electricity The ratio calculation of discharge time obtains between appearance.Discharge time is in a linear relationship with capacitance, i.e. testing capacitance and reference capacitance Between capacitance ratio and the ratio of discharge time it is in a linear relationship, then according to the capacitance of reference capacitance, then by be measured The capacitance of testing capacitance can be calculated in the ratio of discharge time between capacitor and reference capacitance.

Discharge curve that the present embodiment testing capacitance, reference capacitance are recorded as shown in figure 4, wherein abscissa is the time, Testing capacitance is from the first voltage value V0It is discharged to second voltage value VtThe discharge time of Shi Suoxu is μ s, testing capacitance and reference electricity Discharge time difference between appearance is ns, then μ+n is reference capacitance from the first voltage value V0It is discharged to second voltage value VtShi Suoxu's Discharge time, specifically (1) is calculated the value of testing capacitance according to the following formula;

C = C0*μ/(μ+n) (1)

Wherein C is the capacitance of testing capacitance, C0For the capacitance of reference capacitance.

In the present embodiment, measurement method further includes distributed capacitance removal step, specific steps are as follows: successively with testing capacitance The distribution capacity of both ends conducting wire calculates the capacitance of target capacitance according to measured capacitance value step as target capacitance, obtain to The distributed capacitance of capacitor both ends conducting wire is surveyed, and calculates the final capacitance of testing capacitance according to obtained distributed capacitance.

Capacitor all exists between any two insulated electric conductor, adjacent two circle of adjacent conducting wire, coil, discrete element and All there is certain capacitor, as distribution capacity, influence etc. of the distribution capacity to circuit between each section inside one element Imitate a capacitor on to circuit in parallel.In low-frequency ac circuit, the capacitive reactance of distribution capacity is very big, and the influence to circuit is not Greatly, therefore in low-frequency ac circuit, it can not generally consider the influence of distribution capacity, but for high frequency ac circuit, distribution The influence of capacitor cannot be ignored.

Since the size of small capacitance is in millimeter rank, the capacitance signal that can be obtained is very faint, thus directly surveys Distribution capacity is also superimposed in the capacitor measured, and the value of usually distribution capacity is often more much greater than testing capacitance itself. The present embodiment is on the basis of above-mentioned measured capacitance value, by measuring the distributed capacitance at testing capacitance both ends, Ke Yiyou respectively Effect eliminates influence of the distribution capacity to measurement result in micro capacitance, obtains the accurate capacitance of testing capacitance, and traditional Resonance method and succusion etc. can not overcome the influence of distribution capacity.

In the present embodiment, when calculating the capacitance of target capacitance, connected especially by by the conducting wire at end where target capacitance Into charging and discharging circuit, discharge time needed for measuring target capacitance.Testing capacitance both ends conducting wire is successively connected to charge and discharge In circuit, that is, it can measure discharge time needed for obtaining both ends distribution capacity, so that both ends distributed capacitance be calculated.

In the present embodiment, the distributed capacitance of both ends conducting wire is subtracted by the capacitance for the testing capacitance being calculated, and is obtained Obtain the final capacitance of testing capacitance.

As shown in figure 5, C1 and C2 are equivalent to the spuious distribution capacity of the both ends testing capacitance C conducting wire etc. respectively, A, B are respectively The wire interface at testing capacitance both ends.When being measured to testing capacitance, as shown in fig. 6, the end A, B is accessed to charge and discharge first In circuit, the capacitance of testing capacitance is calculated by above-mentioned measured capacitance value step, that is, includes the total capacitance value of distribution capacity; The both ends testing capacitance C distribution capacity C1 and C2 are measured respectively again, wherein distribution capacity C1 is electricity of the end A relative to ground Appearance, distribution capacity C2 are capacitor of the end B relative to ground, respectively terminate the end A, B in charging and discharging circuit according to above-mentioned capacitor Value measuring process measures, and can be obtained the capacitance of distribution capacity C1 and C2;Finally by capacitance (A, B of testing capacitance Capacitor between both ends) subtract acquisition distribution capacity C1 and C2 capacitance to get arrive testing capacitance C final capacitance, Distributed capacitance is eliminated in final capacitance.

Above-mentioned only presently preferred embodiments of the present invention, is not intended to limit the present invention in any form.Although of the invention It has been disclosed in a preferred embodiment above, however, it is not intended to limit the invention.Therefore, all without departing from technical solution of the present invention Content, technical spirit any simple modifications, equivalents, and modifications made to the above embodiment, should all fall according to the present invention In the range of technical solution of the present invention protection.

Claims (8)

1. a kind of micro capacitance method, which is characterized in that the measurement method includes measured capacitance value step, the capacitor It is worth measuring process are as follows: required when measurement testing capacitance and reference capacitance are discharged to second voltage value from the first voltage value respectively to put The electric time calculates the capacitance of testing capacitance according to the discharge time that the relationship and measurement of discharge time and capacitance obtain; The specific measuring process of the discharge time are as follows: successively testing capacitance, reference capacitance are connected in same charging and discharging circuit, passed through The charging and discharging circuit will make the capacitor of the access start to discharge after the capacitor charging to the first voltage value of access, and records and put Discharge time needed for electricity to second voltage value, discharge time needed for measurement obtains testing capacitance, reference capacitance respectively;It is described The capacitance of testing capacitance is with specific reference to discharge time between the capacitance and testing capacitance and reference capacitance of reference capacitance Ratio calculation obtains.
2. micro capacitance method according to claim 1, it is characterised in that: the charging and discharging circuit is believed by pulse Number generator makes the capacitor of access discharge to the capacitor charging of access, by discharge resistance;The charging and discharging circuit passes through the time Converter records discharge time.
3. micro capacitance method according to claim 2, it is characterised in that: the measured capacitance value step further includes Reference capacitance configuration step, specially configuration are in the capacitor of same quantitative levels as reference capacitance with testing capacitance.
4. micro capacitance method according to claim 3, it is characterised in that: the second voltage value is designated ratio The first voltage value, wherein 0 < designated ratio < 100%.
5. micro capacitance method according to claim 1, which is characterized in that the capacitance of the testing capacitance is specific It is calculated according to the following formula;
C = C0*μ/(μ+n)
Wherein C is the capacitance of testing capacitance, C0For the capacitance of reference capacitance, μ is testing capacitance from the first voltage value V0Electric discharge To second voltage value VtThe discharge time of Shi Suoxu, μ+n are reference capacitance from the first voltage value V0It is discharged to second voltage value VtWhen Required discharge time, wherein discharge time of the n between testing capacitance and reference capacitance is poor.
6. micro capacitance method described according to claim 1~any one of 4, which is characterized in that the measurement side Method further includes distributed capacitance removal step, specific steps are as follows: successively using the distribution capacity of testing capacitance both ends conducting wire as mesh Capacitor is marked, the capacitance of target capacitance is calculated according to the measured capacitance value step, obtains the distribution of testing capacitance both ends conducting wire Capacitance, and according to the final capacitance of testing capacitance after obtained distributed capacitance calculating removal distributed capacitance.
7. micro capacitance method according to claim 6, it is characterised in that: the capacitance for calculating target capacitance When, it is connected in charging and discharging circuit especially by by the conducting wire at end where target capacitance, when electric discharge needed for measuring target capacitance Between.
8. micro capacitance method according to claim 7, it is characterised in that: the final capacitance of shown testing capacitance It is obtained by the distributed capacitance that the capacitance for the testing capacitance being calculated subtracts both ends conducting wire.
CN201510894356.9A 2015-12-08 2015-12-08 A kind of micro capacitance method CN105527501B (en)

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CN106501618B (en) * 2016-12-30 2019-02-26 上海东软载波微电子有限公司 Capacitor's capacity measuring circuit
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