CN104168023B - A kind of high-precision adc - Google Patents
A kind of high-precision adc Download PDFInfo
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- CN104168023B CN104168023B CN201410426242.7A CN201410426242A CN104168023B CN 104168023 B CN104168023 B CN 104168023B CN 201410426242 A CN201410426242 A CN 201410426242A CN 104168023 B CN104168023 B CN 104168023B
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Abstract
The invention belongs to electronic circuit technology field, and in particular to a kind of high-precision adc.The present invention forms voltage measuring section by the second voltage follower 102 and analog-digital converter 104 being sequentially connected；The digital analog converter 103 and first voltage follower 101 being sequentially connected form voltage generation section；Subtraction circuit 108 is formed by first resistor 110, second resistance 111,3rd resistor 112, the 4th resistance 113 and operational amplifier 115；By the 5th resistance 114 voltage amplifier 109 is formed with instrument amplifier 116；Subtraction circuit 108 forms residual voltage discharge portion with voltage amplifier 109.Beneficial effects of the present invention are, 20bit resolution ratio can be realized, 1MHZ sample rates, 1LSB maximum integral nonlinearities, full scale transformed error is less than 1ppm, 6 Semi-digital universal meters are can apply to, can also be applied to require higher high accuracy digital acquisition device and high-end instrument and meter to sample rate.Present invention is particularly suitable for high-precision adc.
Description
Technical field
The invention belongs to electronic circuit technology field, and in particular to a kind of high-precision adc.
Background technology
With the continuous development of semiconductor technology, Digital Signal Processing and e measurement technology, the production of analog-digital converter
Product quantity is skyrocketed through, and product type is enriched constantly.Analog-digital converter is the conversion of analog signal and data signal, is modern number
The most basic and most important part of word e measurement technology.First item modulus is designed from the last century 50's AT＆T Labs
Converter, various types of analog-digital converters, also experienced by the change of discrete component to large scale integration by now.
The now precision level of commercial integrated high-resolution analog-digital converter limits it in many delicate metering occasions
Use, such as microvolt step voltage measurement, smart power metering.The static accuracy performance of analog-digital converter, it is non-to lead to common integral
Linearly (Integral Nonlinearity, INL), differential nonlinearity (Differential nonlinearity, DNL), mistake
Error (Zero Error), gain error (Gain Error) is adjusted to characterize.Above-mentioned parameter is respectively provided with temperature characterisitic, with temperature
Change can accordingly change.
The integrated A/D converter of actual use, offset error and gain error are easily calibrated.And the non-linear table of device
Now at different temperatures in the inhomogeneities of each code value, then high-resolution integrates A/D and needs to establish based on each code value not
Calibration table under synthermal improves precision.So substantial amounts of data operation make it that this method is worthless.Therefore line is improved
Property degree for improve A/D converter precision property it is significant.
Integrated 16bit, 18bit the resolution ratio A/D converter of commercialization, which is typically based on, gradually compares type structure, 22bit, 24bit
Resolution ratio A/D converter is typically based on sigma-delta type structures.Such as：16bit resolution ratio AD7626, its LNL are 1LSB；
18bit resolution ratio AD7960, its LNL are 0.8LSB；22bit resolution ratio AD7716, its LNL are 20LSB；23-24bit resolution ratio
ADS1675, its LNL are 147LSB；24bit resolution ratio AD7760, its LNL are 125LSB.It can draw：High-resolution modulus
Converter, its linearity are simultaneously bad.Therefore commercial integrated high resolution A/D converters by its it is nonlinear influence, its precise voltage
Conversion digit is less than 18bit.
High-accuracy voltage measurement needs the A/D converter of high linearity.Used in traditional 6 half -8 Semi-digital universal meters
Double-bevel integrates structure or more inclineds integration structure, such as " 70 series " digital multimeter of FLUKE companies, Agilent companies
" 3458A " digital multimeter [2].The analog-digital converter of this kind of structure is generally by integrator, comparator, accurate voltage or electric current
With reference to and precision interval clock with reference to composition, its general principle is to convert voltages into time quantum to measure.Although it has excellent
Different precision property, but its sample rate is very low, and circuit using discrete component by largely being formed so that and it has design
The defects of difficulty is big, manufacturing cost is high, bulky.
The content of the invention
The purpose of the present invention, aiming above mentioned problem, propose a kind of 20 high-precision adcs.
Technical scheme：As shown in figure 1, a kind of high-precision adc, it is characterised in that including the first electricity
Press follower 101, second voltage follower 102, digital analog converter 103, analog-digital converter 104, control logic module 105, list
Dpdt double-pole double-throw (DPDT) analog switch 106, first resistor 110, second resistance 111,3rd resistor 112, the 4th resistance 113, the 5th resistance
114th, operational amplifier 115 and instrument amplifier 116；Digital analog converter 103 and analog-digital converter 104 and control logic module
105 interconnection；The output end and reverse input end of the input termination second voltage follower 102 of analog-digital converter 104；Single-pole double throw
The control termination control logic module 105 of analog switch 106, the moving contact for switching 106 connect the forward direction of second voltage follower 102
Input；The positive input of the output termination first voltage follower 101 of digital analog converter 103；First voltage follower 101
Reverse input end and its output end interconnect, its output end is followed by the reverse input of operational amplifier 115 by 3rd resistor 112
End；3rd resistor 112 and the tie point of the reverse input end of operational amplifier 115 are followed by operational amplifier by the 4th resistance 113
115 output end and the positive input of instrument amplifier 116；The positive input of operational amplifier 115 passes through second resistance
It is grounded after 111；The tie point of the positive input of operational amplifier 115 and second resistance 111 is followed by defeated by first resistor 110
Enter signal and control the first stationary contact of analog switch 106；Second stationary contact of control analog switch 106 connects instrument amplifier
116 output end；The 5th resistance 114, its reverse input end ground connection are accessed in the resistance port of instrument amplifier 116.
Beneficial effects of the present invention are, analog-digital converter of the invention can realize 20bit resolution ratio, 1MHZ sample rates,
1LSB maximum integral nonlinearities, full scale transformed error are less than 1ppm, can apply to 6 Semi-digital universal meters, can also apply
In to the sample rate higher high accuracy digital acquisition device of requirement and high-end instrument and meter；Also have global design it is simplified, into
The advantages of this reduction, small volume, simple to operate and stable performance.
Brief description of the drawings
Fig. 1 is the structural representation of the analog-digital converter of the present invention.
Embodiment
The present invention is described in detail below in conjunction with the accompanying drawings
As shown in figure 1, the high-precision adc of the present invention, including first voltage follower 101, second voltage follow
Device 102, digital analog converter 103, analog-digital converter 104, control logic module 105, the electricity of single pole double throw analog switch 106, first
Resistance 110, second resistance 111,3rd resistor 112, the 4th resistance 113, the 5th resistance 114, operational amplifier 115 and instrument amplification
Device 116；Digital analog converter 103 and analog-digital converter 104 interconnect with control logic module 105；The input of analog-digital converter 104
Connect the output end and reverse input end of second voltage follower 102；The control termination control logic of single pole double throw analog switch 106
Module 105, the moving contact for switching 106 connect the positive input of second voltage follower 102；The output end of digital analog converter 103
Connect the positive input of first voltage follower 101；The reverse input end of first voltage follower 101 interconnects with its output end,
Its output end is followed by the reverse input end of operational amplifier 115 by 3rd resistor 112；3rd resistor 112 and operational amplifier
The tie point of 115 reverse input ends is followed by the output end and instrument amplifier 116 of operational amplifier 115 by the 4th resistance 113
Positive input；The positive input of operational amplifier 115 after second resistance 111 by being grounded；Operational amplifier 115 is just
The of input signal and control analog switch 106 is followed by by first resistor 110 to the tie point of input and second resistance 111
One stationary contact；Second stationary contact of control analog switch 106 connects the output end of instrument amplifier 116；The electricity of instrument amplifier 116
Hinder port and access the 5th resistance 114, its reverse input end ground connection.
Wherein, the second voltage follower 102 and analog-digital converter 104 being sequentially connected form voltage measuring section；Successively
The digital analog converter 103 and first voltage follower 101 of connection form voltage generation section；By first resistor 110, second resistance
111st, 3rd resistor 112, the 4th resistance 113 and operational amplifier 115 form subtraction circuit 108；By the 5th resistance 114 with
Instrument amplifier 116 forms voltage amplifier 109；Subtraction circuit 108 forms residual voltage electric discharge with voltage amplifier 109
Part.
Control logic 105 controls analog switch 106 to access input signal Vin(t), analog-digital converter 104 assesses input signal
Amount, control logic 105 control high-precision adc 103 to produce and the approximate voltage V of input signal amountda(t).Subtraction is transported
Circuit 108 is calculated by input voltage signal Vin(t) V is subtractedda(t), difference voltage amplifies g times by voltage amplifier 109.Control
Logic 105 controls analog switch 106 to access the output signal of voltage amplifier 109, and analog-digital converter 104 measures residual voltage Vrs
(t) it is V that, control logic 105, which calculates analog-digital converter output quantity,da(t)+Vrs(t)/g。
The present invention needs to be more than the commercial integrated digital to analog converter of 20bit, INL less than 1LSB using resolution ratio.Its precision
Level depends on the precision level of digital analog converter 103.In the range of precision level, the resolution ratio of analog-digital converter depends on instrument
The multiplication factor of table amplifier 116.
The present invention operation principle be：
Digital analog converter 103 generates one and the approximate known voltage amount V of input signal amount sizeda(t), i.e. input voltage
Small magnitude of voltage is differed with known voltage；Small voltage difference is obtained using subtraction circuit 108, then to this small electric
Voltage V is obtained after pressing big g timesrs(t)；Measured again using analog-digital converter 104, obtain the transformation result of input voltage
For Vda(t)+Vrs(t)/g.Its specific implementation process is as follows：
First time voltage measurement：Control logic 105 controls analog switch 106 to turn on input signal Vin(t), analog-digital converter
104 assess input signal amount, and it is approximately electric with input signal amount that control logic 105 controls high-precision adc 103 to produce
Pressure amount Vda(t).When high-precision adc 103 selects a 20bit resolution ratio, INL is less than 1LSB, and sample rate is more than 1Mhz
During integrated digital to analog converter, such as ADI companies AD5791, then caused voltage Vda(t) there is 1ppm precision.
After first time voltage measurement and before second of voltage measurement, subtraction circuit 108 is by input voltage signal Vin(t)
Subtract Vda(t), difference voltage is amplified g times by voltage amplifier 109 and exported.
Second of voltage measurement：Control logic 105 controls the output signal of 106 conducting voltage amplifier of analog switch 109, mould
Number converter 104 measures residual voltage Vrs(t) it is V that, control logic 105, which calculates analog-digital converter output quantity,da(t)+Vrs(t)/g。
Work as Vrs(t) when/g precision is less than 20 analog-digital converter 1LSB, and voltage Vda(t) there is 1ppm precision, then analog-to-digital conversion
Device integral nonlinearity can be less than 1LSB.
Need to realize the analog-digital converter of 20bit resolution ratio, and reach 1ppm full scale precision.Such as range is 10V,
It is required that converter can identify 19uV voltages, then the V in output quantityrs(t)/g items need the accuracy rating in analog-digital converter 104
Within, and multiplication factor g enables to Vrs(t)/g is accurate to 19uV.
Analog-digital converter 104 can have the integrated converter of 10-16 effective accuracy positions.When analog-digital converter 104
, it is necessary to which the multiplication factor of instrument amplifier 116 is bigger when digit is lower.Such as design analog-digital converter 104 only identifies 10-3Magnitude
Voltage, then multiplication factor g must be at least 103Times.
All operational amplifiers used in converter are respectively provided with low-noise characteristic, and pink noise characteristic should be than overall essence
The horizontal small an order of magnitude of degree,
As the multiplication factor g of instrument amplifier 119 and 104 rational design at a high speed, and exclude amplifier noise influence, then mould
The precision of number converter is determined by the precision of digital analog converter 103, such as digital analog converter 103 has the 1LSB linearities, then mould
Number converter has the 1LSB linearities.
Analog-digital converter sample rate is by conversion speed of the sample rate of analog-digital converter 104 with digital analog converter 103, mould
Intend the maximum in the switching speed of switch to determine.According to current integrated device manufacture level, high-precision adc 103 exists
1Mhz, such as ADI companies AD5791 can most be reached during 20bit soon, i.e. sampling rate of the invention can most reach 1Mhz soon.For
Realize 1MHZ sample rate, control logic 108 work clock in the present invention should be 1 to 2 times of sample rate, therefore ARM,
FPGA, DSP can be used as control logic.
Claims (1)
1. a kind of high-precision adc, it is characterised in that including first voltage follower (101), second voltage follower
(102), digital analog converter (103), analog-digital converter (104), control logic module (105), single pole double throw analog switch
(106), first resistor (110), second resistance (111), 3rd resistor (112), the 4th resistance (113), the 5th resistance (114),
Operational amplifier (115) and instrument amplifier (116)；Digital analog converter (103) and analog-digital converter (104) and control logic mould
Block (105) interconnects；The output end and reverse input end of the input termination second voltage follower (102) of analog-digital converter (104)；
The control termination control logic module (105) of single pole double throw analog switch (106), the moving contact of switch (106) connect second voltage
The positive input of follower (102)；The output of digital analog converter (103) terminates the positive defeated of first voltage follower (101)
Enter end；The reverse input end of first voltage follower (101) interconnects with its output end, and its output end passes through 3rd resistor (112)
It is followed by the reverse input end of operational amplifier (115)；3rd resistor (112) and the company of operational amplifier (115) reverse input end
Contact is followed by the output end of operational amplifier (115) by the 4th resistance (113) and the positive of instrument amplifier (116) inputs
End；The positive input of operational amplifier (115) is grounded afterwards by second resistance (111)；Operational amplifier (115) it is positive defeated
Enter end to be followed by input signal by first resistor (110) with the tie point of second resistance (111) and control analog switch (106)
First stationary contact；Second stationary contact of control analog switch (106) connects the output end of instrument amplifier (116)；Instrument amplifier
(116) the 5th resistance (114), its reverse input end ground connection are accessed in resistance port；
Wherein, the second voltage follower (102) and analog-digital converter (104) being sequentially connected form voltage measuring section；Successively
The digital analog converter (103) and first voltage follower (101) of connection form voltage generation section；By first resistor (110),
Two resistance (111), 3rd resistor (112), the 4th resistance (113) and operational amplifier (115) form subtraction circuit
(108)；Voltage amplifier (109) is formed by the 5th resistance (114) and instrument amplifier (116)；Subtraction circuit (108) with
Voltage amplifier (109) forms residual voltage discharge portion；
The control logic (105) is used to control single pole double throw analog switch (106) access input signal Vin(t) or access voltage
The output signal of amplifier 109, and control digital analog converter (103) to produce and the approximate voltage V of input signal amountda(t)；
The subtraction circuit (108) is used for input voltage signal Vin(t) V is subtractedda(t), difference voltage is put through overvoltage
Big device (109) amplifies g times；
The analog-digital converter (104) is used to measure residual voltage Vrs(t), control logic (105) calculates analog-digital converter output
Measure as Vda(t)+Vrs(t)/g；
The specification of the digital analog converter (103) is that resolution ratio 20bit, INL is less than 1LSB, and sample rate is more than 1Mhz；Then obtain
Vda(t) there is 1ppm precision；
Analog-digital converter (104) range is 10V, and can identify 19uV voltages, then analog-digital converter (104) is put with voltage
The relation of big device (109) is：Analog-digital converter (104) can identify 10-3The voltage of magnitude, then multiplication factor g be at least 103Times.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410426242.7A CN104168023B (en) | 2014-08-27 | 2014-08-27 | A kind of high-precision adc |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410426242.7A CN104168023B (en) | 2014-08-27 | 2014-08-27 | A kind of high-precision adc |
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| Publication Number | Publication Date |
|---|---|
| CN104168023A CN104168023A (en) | 2014-11-26 |
| CN104168023B true CN104168023B (en) | 2017-12-01 |
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| CN201410426242.7A Expired - Fee Related CN104168023B (en) | 2014-08-27 | 2014-08-27 | A kind of high-precision adc |
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Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2020181485A1 (en) | 2019-03-12 | 2020-09-17 | 深圳市汇顶科技股份有限公司 | Analog-to-digital converter and related chip |
| US10873338B1 (en) | 2019-07-30 | 2020-12-22 | Analog Devices International Unlimited Company | Calibration method for precision signal chain linearity |
| CN116203084B (en) * | 2023-02-09 | 2024-01-23 | 广州海谷电子科技有限公司 | Method for realizing humidity-sensitive capacitance sensor based on switch capacitance measurement and sensor |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6127958A (en) * | 1997-09-11 | 2000-10-03 | Hyundai Electronics Industries Co., Ltd. | Analog/digital converting circuit |
| CN1929309A (en) * | 2005-09-08 | 2007-03-14 | 安捷伦科技有限公司 | Precision low noise-delta-sigma adc |
| CN100471069C (en) * | 2001-10-03 | 2009-03-18 | Nxp股份有限公司 | Analogue to digital converter |
-
2014
- 2014-08-27 CN CN201410426242.7A patent/CN104168023B/en not_active Expired - Fee Related
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6127958A (en) * | 1997-09-11 | 2000-10-03 | Hyundai Electronics Industries Co., Ltd. | Analog/digital converting circuit |
| CN100471069C (en) * | 2001-10-03 | 2009-03-18 | Nxp股份有限公司 | Analogue to digital converter |
| CN1929309A (en) * | 2005-09-08 | 2007-03-14 | 安捷伦科技有限公司 | Precision low noise-delta-sigma adc |
Non-Patent Citations (1)
| Title |
|---|
| 高精度低成本仪表放大器的分析研究;高涛;《自动化仪表》;19871127;第14-17页 * |
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