CN104168019B - Analog-digital converter and conversion method for digital multimeter - Google Patents
Analog-digital converter and conversion method for digital multimeter Download PDFInfo
- Publication number
- CN104168019B CN104168019B CN201410350774.7A CN201410350774A CN104168019B CN 104168019 B CN104168019 B CN 104168019B CN 201410350774 A CN201410350774 A CN 201410350774A CN 104168019 B CN104168019 B CN 104168019B
- Authority
- CN
- China
- Prior art keywords
- switch
- voltage
- analog
- digital
- operational amplifier
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Abstract
The present invention relates to modulus conversion technique field, and in particular to for the analog-digital converter and conversion method of digital multimeter, it can be changed to alternating voltage, DC voltage.The framework of whole converter is to be detected voltage, positive reference voltage, negative reference voltage to carry out integral operation, then integrated waveform is measured with analog-digital converter, positive reference voltage, negative reference voltage is controlled with respect to the switch time of inductive switch to control the waveform of integration by feeding back.The analog-to-digital conversion of ac voltage signal, d. c. voltage signal can be realized simultaneously；Precision can reach the requirement of six Semi-digital multimeters；Under conditions of equal accuracy, conversion speed is faster than equal analog-digital conversion ic；The RMS conversion of the AC signal of various species can be carried out；The circuit of realization is simple, and integrated circuit used can domesticize, cheap.
Description
Technical field
The present invention relates to modulus conversion technique field, and in particular to for the analog-digital converter of digital multimeter and conversion side
Method, it can be changed to alternating voltage, DC voltage.
Background technology
Digital multimeter needs to measure alternating current and direct current signal simultaneously, because the analog-digital converter in conventional digital multimeter
The true rms measurement that can not be exchanged, so digital multimeter is generally required using two sets of independent analog-digital converters come real
The measurement of existing AC and DC.Measurement DC voltage needs to use high-precision analog-digital converter integrated circuit, expensive, high
The test speed of precision is slow, and integrated circuit used can not domesticize.The real effective of Measuring Alternating Current Signal needs to use
Special RMS conversion integrated circuit, such as AD637, it is expensive, it is necessary to import, and also accuracy and speed is not high,
And the RMS conversion of standard sine wave can only be carried out, has distortion if not sine wave or sine wave, converts
Real effective have error.
The content of the invention
For above-mentioned technical problem, it is an object of the invention to provide the analog-digital converter for digital multimeter and turn
Method is changed, the analog-to-digital conversion of ac voltage signal, d. c. voltage signal can be realized simultaneously；Precision can reach six Semi-digitals
The requirement of multimeter；Under conditions of equal accuracy, conversion speed is faster than equal analog-digital conversion ic；It can enter
The RMS conversion of the AC signal of the various species of row；The circuit of realization is simple, and integrated circuit used can domesticize,
It is cheap.
Realize that the technical scheme of the goal of the invention of the present invention is as follows：
For the analog-digital converter of digital multimeter, including a detection input, the detection input incoming transport is detected
Electric current or access DC detecting electric current are surveyed, for inputting the positive reference voltage input of positive reference voltage and for inputting negative benchmark
The negative reference voltage input of voltage, and the first electric capacity, the second operational amplifier, the first analog-digital converter, the second modulus turn
Parallel operation and digital logic device；
The detection input connects digital logic device, positive reference voltage input by first resistor, first switch
Connected by second resistance, second switch and digital logic device, bear reference voltage input and pass through 3rd resistor, the 3rd switch
It is connected with digital logic device, first switch, second switch, third switch are turned on and off by digital logic device control；
One end of first electric capacity, the input of the second operational amplifier simultaneously connect first switch, second switch, the 3rd opened
Close, the other end of the first electric capacity, the second operational amplifier output end and connect afterwards with and the first analog-digital converter, the second mould that connect
Number converter connects；The data of collection are transferred to digital logic device by first analog-digital converter, the second analog-digital converter
And swapped with the data in digital logic device.
Such scheme is employed, the framework of whole converter is to be detected voltage, positive reference voltage, negative reference voltage to carry out
Integral operation, integrated waveform then is measured with analog-digital converter, control positive reference voltage, negative reference voltage relative by feeding back
The switch time of inductive switch controls the waveform of integration.The technical program is, create a kind of high accuracy, at high speed, can be same
When for the data converting circuit testing DC voltage with exchange real effective.The precision of test DC voltage can meet six and half
The demand of Accuracy Figure multimeter, lower than the integrated circuit cost of equal accuracy, speed is fast.The true of AC signal, which can be tested, to be had
Valid value, there is more preferable accuracy and speed advantage than existing RMS conversion integrated circuit, it is most important that various shapes can be tested
The AC signal real effective of shape, it can meet on electric power to the true rms measurement for the alternating voltage that distorts.This analog-digital converter can
With high-precision digital-to-analogue conversion integrated circuit and RMS conversion integrated circuit outside surrogate simultaneously.
Further, stabilization is connected between the first switch, second switch, third switch and the second operational amplifier
Circuit, the stabilizing circuit include the first operational amplifier, the 5th resistance, the 6th resistance and for protecting the second operation amplifier
The protection circuit of device, the inverting input of the first operational amplifier simultaneously connect first switch, second switch, third switch, with mutually defeated
Enter end ground connection；5th resistance one end is connected with the first operational amplifier output terminal, protection circuit one end and first switch, the first electricity
Hold and the input in the same direction of the second operational amplifier is connected, the 6th resistance one end ground connection, the 5th resistance other end, protection circuit are another
One end, the 6th resistance other end are connected after being connected with the inverting input of the second operational amplifier.
Limited amplitude protection electricity is connected between second operational amplifier and the first analog-digital converter, the second analog-digital converter
Road, limiter protection circuit include being serially connected in the 7th resistance between the second operational amplifier output terminal and the second analog-digital converter,
Second voltage-regulator diode, and the 9th resistance, the 3rd steady being attempted by between the second analog-digital converter and the second voltage-regulator diode
Press diode and the tenth resistance, the 3rd voltage-regulator diode and the tenth the resistance concatenation.
Voltage follower is connected with before second analog-digital converter, it includes the 6th operational amplifier, the 11st electricity
Hinder, second is connected with the output end of the 6th operational amplifier after inverting input the 11st resistance of concatenation of the 6th operational amplifier
Analog-digital converter, the in-phase input end of the 6th operational amplifier connect the output end of the second operational amplifier.
It is a further object of the present invention to provide a kind of D conversion method for digital multimeter, comprise the following steps：
Step 1: alternating voltage to be measured or DC voltage V0 input by turning on first switch, and pass through first resistor
R1 charges to the first electric capacity C1；
Step 2: conducting second switch is passed through positive reference voltage V1, positive reference voltage V1 is by second resistance R2 to first
Electric capacity C1 is charged；
Turn on the 3rd switch and be passed through negative reference voltage V 2, negative reference voltage V 2 is entered by 3rd resistor R3 to the first electric capacity C1
Row charging；
Wherein, when second switch turns on, the 3rd switch OFF；During three switch conductions, second switch shut-off；Second opens
Pass, the 3rd switch are respectively turned on once, are single analog-digital conversion process；
Step 3: the alternating voltage or DC voltage to be measured of input, positive reference voltage, negative reference voltage are by operational amplifier
Carry out operation amplifier output voltage waveforms and pass to the second analog-digital converter to carry out data conversion, obtain oblique when voltage rises
Slope N2 when rate N1 and voltage decline, then the calculation formula by single data conversion：
The real effective of alternating voltage to be measured or the virtual value of DC voltage is calculated；
Step 4: when voltage to be measured is DC voltage, turn by digital logic device computing and by the single repeatedly tested
Data accumulation averaging is changed, obtains DC voltage value；
When voltage to be measured is alternating voltage, the single conversion data summed square repeatedly tested and then averaging are opened into root
Number, obtain the real effective of alternating voltage to be measured.
When control source to be measured is zero, the time of second switch conducting and the time of the 3rd switch conduction are equal；When treating
Survey control source is timing, and second switch ON time is less than the 3rd switch conduction times；When control source to be measured is bears, the
Two switch conduction times are more than the 3rd switch conduction times；So ensure the charge balance on the first electric capacity C1.
The time of the single analog-digital conversion process of the present invention is 100ns~100us, and conversion speed is fast.
Digital logic device controls second switch and the 3rd ON time switched by feeding back, and makes operational amplifier defeated
Go out voltage to swing up and down in the magnitude of voltage of setting, ensure the high accuracy of detection conversion with this.
Brief description of the drawings
Fig. 1 is the circuit theory diagrams of analog-digital converter of the present invention；
Fig. 2 is control source to be measured when being zero, the oscillogram of op-amp output voltage；
Fig. 3 is that control source to be measured is timing, the oscillogram of op-amp output voltage；
Fig. 4 is that control source to be measured is the oscillogram of op-amp output voltage when bearing；
Fig. 5 is the oscillogram of op-amp output voltage when carrying out data conversion to DC voltage and alternating voltage.
Embodiment
The present invention can be used in six Semi-digital multimeters, High-accuracy direct current voltage measurement and AC Voltage TRMS and survey
Amount field.It can be used for substituting the RMS conversion integrated circuit such as existing AD637, AD636, AD536.It may also be used for substituting
The sigma delta data converters of 16~24.The present invention is specifically described below in conjunction with the accompanying drawings.
Referring to Fig. 1, for the analog-digital converter of digital multimeter, including for incoming transport or direct current sensed current
Detection input V0, for the positive reference voltage V1 inputs and the input of negative reference voltage V 2 of input reference voltage, Yi Ji
One electric capacity C1, the second operational amplifier U2, the first analog-digital converter U3, the second analog-digital converter U5 and digital logic device U4；
Positive reference voltage is a positive voltage caused by other circuits or reference voltage source, bear reference voltage V 2 be other circuits or
A negative voltage caused by reference voltage source；
Detection input V0 passes through first resistor R1, first switch K1 connections digital logic device U4, positive reference voltage V1
Input is connected by second resistance R2, second switch K2 with digital logic device U4, bears the input of reference voltage V 2 by the
Three resistance R3, the 3rd switch K3 are connected with digital logic device U4, and first switch, second switch, third switch are by Digital Logic
Device control is turned on and off；Wherein, first switch K1 effect is that voltage signal to be measured is accessed or disconnected, and is entered during access
Row measurement, carry out during disconnection whole analog to digital conversion circuit from resetting, first switch K1 is treated when turning on by first resistor R1
Survey voltage to charge to the first electric capacity C1, because the charging interval is much smaller than R1C1 constants, charging current is approximately equal toWhen second switch K2 is turned on, positive reference voltage V1 charges by second resistance R2 to the first electric capacity C1, because
R2C1 constants are much smaller than for the charging interval, so charging current is approximately equal toDuring the 3rd switch K3 conductings, base is born
Quasi- voltage V2 charges by 3rd resistor R3 to the first electric capacity C1, because the charging interval is much smaller than R3C1 constants, fills
Electric current is approximately equal toFirst switch K1, second switch K2, the 3rd switch K3 are analog switch.First switch
K1, second switch K2, the 3rd switch K3 are controlled by digital logic device U4, realize the work(of the short circuit of 1 and 2 pin or the short circuit of 1 and 3 pin
Energy, the i.e. function of turn-on and turn-off.
Wherein, the first electric capacity C1 one end, the second operational amplifier U2 input and connect first switch K1, second switch
K2, the 3rd switch K3, the other end of the first electric capacity, the second operational amplifier U2 output end and connect afterwards with and the first modulus for connecing
Converter U3, the second analog-digital converter U5 connections；First analog-digital converter U3, the second analog-digital converter U5 pass the data of collection
It is defeated by digital logic device U4 and is swapped with the data in digital logic device.Digital logic device U4 controls the first modulus
Converter U3, the second analog-digital converter U5 carry out analog-to-digital conversion and read the first analog-digital converter U3, the second analog-digital converter U5
The data of output are calculated；In specific implementation, the first analog-digital converter U3 is 8, and the minimum 20MSPS of sample rate modulus turns
Integrated circuit is changed, certain digit is higher or sample rate is higher can；Second analog-digital converter U5 is 10 or 12, is adopted
The minimum 10MSPS of sample rate analog-digital conversion ic, certain digit is more high-precision higher, the higher quilt that can be changed of sample rate
Surveying that signal frequency is more high can be with；Digital logic device U4 programmable digital logic array integrated circuits, generally FPGA；Here
It should be noted that the first analog-digital converter, the second analog-digital converter and digital logic device for commercially directly purchase
Part, concrete model can be used as needed, and superfluous chat just is not done in this particular circuit configurations.
Stabilizing circuit is connected between first switch K1, second switch K2, the 3rd switch K3 and the second operational amplifier U2,
The stabilizing circuit includes the first operational amplifier U1, the 5th resistance R5, the 6th resistance R6 and for protecting the second operation amplifier
The protection circuit CR1 of device, the protection circuit are made up of two diodes；First operational amplifier U1 inverting input simultaneously connects
One switch K1, second switch K2, the 3rd switch K3, the first operational amplifier U1 in-phase input end ground connection, the first operation amplifier
The output end of device concatenates the 5th resistance R5, the 5th resistance and connect after protection circuit CR1, the 6th resistance R6 with the second operational amplifier
U2 inverting input connection, the in-phase input end connection protection circuit CR1 of the second operational amplifier other end.
Limited amplitude protection is connected between second operational amplifier U2 and the first analog-digital converter U3, the second analog-digital converter U5
Circuit, to protect the 6th operational amplifier U6 and the second analog-digital converter U5, limiter protection circuit includes being serially connected in the second fortune
The 7th resistance R7, the second voltage-regulator diode CR2 between amplifier out and the second analog-digital converter are calculated, and is attempted by the
The 9th resistance R9, the 3rd voltage-regulator diode CR3 and the tenth resistance R10 between two analog-digital converters and the second voltage-regulator diode,
3rd voltage-regulator diode CR3 and the tenth resistance the R10 concatenation.And diode group CR4.
Voltage follower is connected with before second analog-digital converter, it includes the 6th operational amplifier U6, the 11st resistance
Output end after R11, the 6th operational amplifier U6 the 11st resistance R11 of inverting input concatenation with the 6th operational amplifier connects
The second analog-digital converter U5 is met, the in-phase input end of the 6th operational amplifier connects the second operational amplifier U2 output end.Its
In, the 8th resistance R8 and the 3rd electric capacity C3 form a LPF.
In the present invention, the first operational amplifier U1, the second operational amplifier U2, the 5th resistance R5, the 6th resistance R6, protection
Circuit CR1, the first electric capacity C1 form an integrating circuit, wherein, protection circuit CR1 is used to protect the second operational amplifier U2,
First electric capacity C1 is integrating capacitor, and the 5th resistance R5, the 6th resistance R6 ensure the stabilization of whole loop；When it is implemented, first
Operational amplifier U1, the 5th resistance R5, the 6th resistance R6, protection circuit CR1, diode group CR4 can be dispensed, to the work(of circuit
It is able to can increase for the optimization of circuit without influence.
Fig. 1 circuit diagram is equally can refer to, realizes another technical scheme of the present invention, the modulus for digital multimeter turns
Method is changed, is comprised the following steps：
Step 1: alternating voltage to be measured or DC voltage V0 input by turning on first switch, and pass through first resistor
R1 charges to the first electric capacity C1；
Step 2: conducting second switch is passed through positive reference voltage V1, positive reference voltage V1 is by second resistance R2 to first
Electric capacity C1 is charged；
Turn on the 3rd switch and be passed through negative reference voltage V 2, negative reference voltage V 2 is entered by 3rd resistor R3 to the first electric capacity C1
Row charging；
Wherein, when second switch turns on, the 3rd switch OFF；During three switch conductions, second switch shut-off；Second opens
Pass, the 3rd switch are respectively turned on once, are single analog-digital conversion process；
Step 3: the alternating voltage or DC voltage to be measured of input, positive reference voltage, negative reference voltage are by operational amplifier
U2 carries out operation amplifier output voltage waveforms and passes to the second analog-digital converter progress data conversion, obtains when voltage rises
Slope N2 when slope N1 and voltage decline, then the calculation formula by single data conversion：
The real effective of alternating voltage to be measured or the virtual value of DC voltage is calculated；Here operational amplifier includes second
Operational amplifier U2 and the 6th operational amplifier U6；
Step 4: when voltage to be measured is DC voltage, turn by digital logic device computing and by the single repeatedly tested
Data accumulation averaging is changed, obtains DC voltage value；
When voltage to be measured is alternating voltage, the single conversion data summed square repeatedly tested and then averaging are opened into root
Number, obtain the real effective of alternating voltage to be measured.
When control source to be measured is zero, the time of second switch conducting and the time of the 3rd switch conduction are equal；When treating
Survey control source is timing, and second switch ON time is less than the 3rd switch conduction times；When control source to be measured is bears, the
Two switch conduction times are more than the 3rd switch conduction times.
The time of single analog-digital conversion process is 100ns~100us, and the specific time sees that practical application is determined.In single mould
In number conversion process, the switches of second switch K2 and the 3rd K3 is respectively turned on once, and the 3rd switch K3 breaks when second switch K2 is turned on
Open, second switch K2 disconnect when the 3rd switch K3 conducting, second switch K2 conducting time plus the 3rd switch K3 conducting when
Between be single analog-to-digital conversion time.Because reference voltage V 1 and reference voltage V 2 one are positive voltage, one is negative voltage,
So being charged when second switch K2 is turned on to the first electric capacity C1, the 3rd switch K3 discharges when turning on to the first electric capacity C1.Second opens
Close the data that K2 and the 3rd switchs the time that K3 is respectively turned on and obtained by digital logic device U4 according to the first analog-digital converter U3
To control.It is typically that second resistance R2 and 3rd resistor R3 resistance is equal in actual circuit, reference voltage V 1 and reference voltage
V2 absolute value of voltage is equal positive and negative opposite.
When control source to be measured is zero, the time just phase of the time of second switch K2 conductings and the 3rd switch K3 conductings
Deng the second operational amplifier U2 output pin voltage oscillogram is shown in Fig. 2.When control source to be measured is timing, second switch K2
ON time will be less than the 3rd switch K3 ON times, to ensure the charge balance on the first electric capacity C1, now the second computing
Amplifier U2 output pin voltage oscillogram is shown in Fig. 3.When control source to be measured is bears, second switch K2 ON times will
More than the 3rd switch K3 ON times, to ensure the charge balance on the first electric capacity C1, the second operational amplifier U2 output is drawn
Pin voltage oscillogram is shown in Fig. 4.
Wherein, digital logic device U4 mainly has two big functions：
First, when controlling the switches of second switch K2 and the 3rd K3 conducting by the first analog-digital converter U3 change data
Between, ensure that the second operational amplifier U2 output voltage is swung up and down in a range of magnitude of voltage of setting, so ensure
Second analog-digital converter collects stable signal.
Second, the voltage waveform that the second analog-digital converter U5 of control exports to the 6th operational amplifier U6 carries out data and turned
Change, obtain slope N2 when slope N1 and the U2 output voltage when the second operational amplifier U2 output voltages rise decline, then
By the way that the magnitude of voltage of direct current to be measured or the real effective of AC signal is calculated；Line number is entered to DC voltage and alternating voltage
During according to conversion, the oscillogram of the second operational amplifier U2 output voltages is shown in Fig. 5, can be with wherein when being changed to alternating current
The exchange of a cycle is electrically divided into some sections to calculate to measure, so reaches the purpose and precision of measurement alternating current
It is high.
Claims (6)
1. the analog-digital converter for digital multimeter, it is characterised in that including a detection input, detection input access
Sensed current or access DC detecting electric current are exchanged, for inputting the positive reference voltage input of positive reference voltage and for defeated
Enter the negative reference voltage input of negative reference voltage, and the first electric capacity, the second operational amplifier, the first analog-digital converter,
Two analog-digital converters and digital logic device；
The detection input connects digital logic device by first resistor, first switch, and positive reference voltage input passes through
Second resistance, second switch and digital logic device connect, and bear reference voltage input and pass through 3rd resistor, the 3rd switch and number
Word logical device is connected, and first switch, second switch, third switch are turned on and off by digital logic device control；
One end of first electric capacity, the input of the second operational amplifier simultaneously connect first switch, second switch, third switch,
The other end of first electric capacity, the second operational amplifier output end and connect afterwards with and the first analog-digital converter, the second modulus that connect
Converter connects；First analog-digital converter, the second analog-digital converter by the data of collection be transferred to digital logic device and
Swapped with the data in digital logic device；
Limiter protection circuit is connected between second operational amplifier and the first analog-digital converter, the second analog-digital converter,
Limiter protection circuit includes being serially connected in the 7th resistance between the second operational amplifier output terminal and the second analog-digital converter, second
Voltage-regulator diode, and be attempted by between the second analog-digital converter and the second voltage-regulator diode the 9th resistance, the 3rd voltage stabilizing two
Pole pipe and the tenth resistance, the 3rd voltage-regulator diode and the tenth the resistance concatenation；
Voltage follower is connected with before second analog-digital converter, it includes the 6th operational amplifier, the 11st resistance, the
After inverting input the 11st resistance of concatenation of six operational amplifiers the second modulus is connected with the output end of the 6th operational amplifier
Converter, the in-phase input end of the 6th operational amplifier connect the output end of the second operational amplifier.
2. it is used for the analog-digital converter of digital multimeter according to claim 1, it is characterised in that the first switch, the
Stabilizing circuit is connected between two switches, the 3rd switch and the second operational amplifier, the stabilizing circuit includes the first operation amplifier
Device, the 5th resistance, the 6th resistance and for protect the second operational amplifier protection circuit, the first operational amplifier it is anti-
Phase input simultaneously connects first switch, second switch, third switch, in-phase input end ground connection；5th resistance one end and the first computing
Amplifier out connects, protection circuit one end and the input in the same direction of first switch, the first electric capacity and the second operational amplifier
Be connected, the 6th resistance one end ground connection, the 5th resistance other end, the protection circuit other end, the 6th resistance other end be connected after with the
The inverting input connection of two operational amplifiers.
3. the D conversion method for digital multimeter, it is characterised in that comprise the following steps：
Step 1: alternating voltage to be measured or DC voltage V0 input by turning on first switch, and pass through R1 pairs of first resistor
First electric capacity C1 is charged；
Step 2: conducting second switch is passed through positive reference voltage V1, positive reference voltage V1 is by second resistance R2 to the first electric capacity
C1 is charged；
Turn on the 3rd switch and be passed through negative reference voltage V 2, negative reference voltage V 2 is filled by 3rd resistor R3 to the first electric capacity C1
Electricity；
Wherein, when second switch turns on, the 3rd switch OFF；During three switch conductions, second switch shut-off；Second switch,
3rd switch is respectively turned on once, is single analog-digital conversion process；
Step 3: the alternating voltage or DC voltage to be measured of input, positive reference voltage, negative reference voltage are carried out by operational amplifier
Operation amplifier output voltage waveforms simultaneously pass to the second analog-digital converter progress data conversion, obtain slope N1 when voltage rises
Slope N2 when declining with voltage, then the calculation formula by single data conversion：
The real effective of alternating voltage to be measured or the virtual value of DC voltage is calculated；
Step 4: when voltage to be measured is DC voltage, pass through digital logic device computing and the single conversion number that will repeatedly test
According to cumulative averaging, DC voltage value is obtained；
When voltage to be measured is alternating voltage, the single conversion data summed square repeatedly tested and then averaging are opened into radical sign, obtained
To the real effective of alternating voltage to be measured.
4. the D conversion method according to claim 3 for digital multimeter, it is characterised in that when voltage to be measured is defeated
Enter when being zero, the time of second switch conducting and the time of the 3rd switch conduction are equal；When control source to be measured is timing, second
Switch conduction times are less than the 3rd switch conduction times；When control source to be measured for it is negative when, second switch ON time is more than the
Three switch conduction times.
5. the D conversion method according to claim 3 for digital multimeter, it is characterised in that single analog-to-digital conversion
The time of process is 100ns~100us.
6. the D conversion method according to claim 3 for digital multimeter, it is characterised in that digital logic device
Second switch and the 3rd ON time switched are controlled by feeding back, makes op-amp output voltage in the magnitude of voltage of setting
Inside swing up and down.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410350774.7A CN104168019B (en) | 2014-07-22 | 2014-07-22 | Analog-digital converter and conversion method for digital multimeter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410350774.7A CN104168019B (en) | 2014-07-22 | 2014-07-22 | Analog-digital converter and conversion method for digital multimeter |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN104168019A CN104168019A (en) | 2014-11-26 |
| CN104168019B true CN104168019B (en) | 2017-11-24 |
Family
ID=51911685
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201410350774.7A Active CN104168019B (en) | 2014-07-22 | 2014-07-22 | Analog-digital converter and conversion method for digital multimeter |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN104168019B (en) |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19938045C2 (en) * | 1998-08-18 | 2003-03-27 | Tektronix Inc | Extended common-mode input range for a delta-sigma modulator |
| CN101741387A (en) * | 2009-12-17 | 2010-06-16 | 上海贝岭股份有限公司 | Integral analogue-to-digital converter and sampling control method thereof |
| CN103245814A (en) * | 2013-05-23 | 2013-08-14 | 张培 | Combined intelligent universal meter |
| CN203984398U (en) * | 2014-07-22 | 2014-12-03 | 常州同惠电子股份有限公司 | Analog to digital converter for digital multimeter |
-
2014
- 2014-07-22 CN CN201410350774.7A patent/CN104168019B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19938045C2 (en) * | 1998-08-18 | 2003-03-27 | Tektronix Inc | Extended common-mode input range for a delta-sigma modulator |
| CN101741387A (en) * | 2009-12-17 | 2010-06-16 | 上海贝岭股份有限公司 | Integral analogue-to-digital converter and sampling control method thereof |
| CN103245814A (en) * | 2013-05-23 | 2013-08-14 | 张培 | Combined intelligent universal meter |
| CN203984398U (en) * | 2014-07-22 | 2014-12-03 | 常州同惠电子股份有限公司 | Analog to digital converter for digital multimeter |
Also Published As
| Publication number | Publication date |
|---|---|
| CN104168019A (en) | 2014-11-26 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN102590609B (en) | The method of mobile terminal and measurement mobile terminal power consumption | |
| CN203630198U (en) | Battery voltage detection circuit | |
| CN204909403U (en) | Electronic clinical thermometer | |
| CN204462255U (en) | Apparatus for measuring capacitance capacity | |
| CN102890243B (en) | A kind of battery electric quantity measuring circuit, measurement apparatus and battery meter | |
| CN206710549U (en) | Multistation DC parameter test device for UIS tests | |
| CN102098368B (en) | Mobile phone | |
| CN103440073B (en) | Get rid of the capacitance sensing circuit of effect of parasitic capacitance | |
| CN103543323A (en) | Current detection device for large direct current charge-discharge facility | |
| CN103604992A (en) | Wireless nuclear phase on-load correction protection method and system for secondary circuit of substation | |
| CN105573391A (en) | Open-circuit voltage control circuit of solar array simulator and open-circuit voltage control method thereof | |
| CN103499733A (en) | Circuit and method for high-precision voltage detection | |
| CN104569899A (en) | High-accuracy high-voltage direct-current transformer calibrator | |
| CN104034956A (en) | Positive/negative voltage measuring circuit | |
| CN104168019B (en) | Analog-digital converter and conversion method for digital multimeter | |
| CN112180176A (en) | Capacitance value measuring circuit and method based on constant current source | |
| CN204228946U (en) | A kind of electric energy meter error calibrating installation | |
| CN203984398U (en) | Analog to digital converter for digital multimeter | |
| CN105675960A (en) | Apparatus and method for measuring open-circuit voltage of piezoelectric device | |
| CN207007937U (en) | A kind of detection circuit of multi-section serial battery voltage | |
| CN205725711U (en) | Highly integrated digital integrator for squirrel cage type hollow-core current transformer | |
| CN203204078U (en) | Test system for measuring earth grounding resistance | |
| CN203894320U (en) | Voltage measuring device | |
| CN103063928B (en) | System for testing earth grounding resistance, and digital coherent detection method | |
| CN203572875U (en) | Current detection device for large direct current charge-discharge facility |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |