CN101272145A - High-speed and high-precision A/D converter - Google Patents
High-speed and high-precision A/D converter Download PDFInfo
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- CN101272145A CN101272145A CNA2007100645891A CN200710064589A CN101272145A CN 101272145 A CN101272145 A CN 101272145A CN A2007100645891 A CNA2007100645891 A CN A2007100645891A CN 200710064589 A CN200710064589 A CN 200710064589A CN 101272145 A CN101272145 A CN 101272145A
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Abstract
The invention discloses a high speed high precision A/D converter which compares a sampling level generated by sampling an input analog signal with a plurality of component level standard voltages generated by a standard voltage generator, obtains a high bit digital code by judging the level that the sampling level is located and gates a pair of analog switches according to the judging result to add the voltage difference of the level that the sampling level is located to a subdivision standard voltage generator; the subdivision standard voltage of multi-level generated by the subdivision standard voltage generator is compared with the sampling level again to judge and converse a low bit digital code; the entire digital codes are synthesized and output by the high bit digital code and the low bit digital code. The A/D converter of the invention reduces the amount of elements and reduces the manufacture difficulties.
Description
Technical field
The present invention relates to a kind of analog to digital (A/D) transducer, particularly a kind ofly can reduce number of elements in a large number, can realize more high-precision high speed, high-precision a/d converter with less circuit scale.
Background technology
Current society has entered the digitized epoch of high speed information, and a large amount of signals needs to handle through high speed, high accuracy number, and this just needs a large amount of high speed, high-precision a/d converter.The early stage complete parallel conversion regime (Flash glimmer structure) that adopts, n position accuracy A/D transducer needs 2n to have the precision resistance that the n bit linear requires, these resistance are connected to precision voltage source through serial connection and with resistance string two, just produce 2n-1 reference power supply signal, connect 2n-1 high-speed comparator behind these reference power supply signals, compare to determine conversion value with input signal.Therefore along with the increase of transducer precision, manufacture difficulty and chip power-consumption will heighten, and to be generally used for precision be A/D converter below eight or eight to this mode.In the high-speed a/d converter of middle and high precision, the normal substep conversion regime that adopts.So-called substep conversion regime, that is, the A/D conversion divides several steps to carry out.The precision of each substep can be lower, therefore can adopt full parallel mode to realize.And the input signal that next is changed step by step is that the digital quantity that last substep converts to is transformed back into analog quantity again with D/A converter, and subtracts each other with the input analog amount of last substep that the back produces.This substep mode has reduced component number significantly, but owing to increased D/A converter and analog quantity subtracter, manufacture difficulty is bigger, and operating rate is difficult for improving.The eighties intermediary and later stages, developed the substep transformation approach of analog switch.This method has been cancelled high-speed d/a transducer required in the conventional method of fractional steps and analog quantity subtracter, and has only increased high-speed analog switch, so operating rate obtains bigger raising, and manufacture difficulty also descends to some extent.
Fig. 1 illustrates the existing A/D converter circuit diagram that adopts the analog switch method of fractional steps.Existing this class A/D converter comprises a multi component level standard voltage generator 102 that is composed in series by m * p equivalent precision resistance, its two ends meet reference voltage V ref1 and Vref2 respectively, m * p wherein equivalent precision resistance is that a component becomes the m group with every p, pick out the rough segmentation component level normal voltage output of (m-1) individual component level by the tie point place of adjacent set, and the tie point place of adjacent resistor picks out the segmentation criteria voltage output end of (p-1) individual component level respectively through an analog switch in group, the control end of the analog switch in the same group formation control end of (n-1) individual analog switch group altogether that links together.(n-1) individual rough segmentation component level normal voltage output of multi component level standard voltage generator 102 is connected to the respective standard voltage input end of a rough segmentation component level normal voltage determining device 103 respectively.The analog signal Vin that imports to rough segmentation component level normal voltage determining device 103, exports rough segmentation component level judgement signal through making comparisons with (m-1) individual rough segmentation component level normal voltage through sampling hold circuit 101 output sampling current potentials.This rough segmentation component level is judged the high order digit value of signal one side through a high order digit encoder 104 output digital signals, provide gating control output through analog switch group Strobe Controller 105 to the control end of the corresponding simulation switches set of institute's gating on the other hand, make interior (p-1) the individual segmentation component level normal voltage of rough segmentation group of institute's gating transport to a segmentation component level normal voltage determining device 106, through segmenting component level judgement signal with the output of comparing from the sampled signal of sampling hold circuit 101.This segmentation component level is judged the low order bit value of signal through a low order bit encoder 107 output digital signals.The high order digit value of digital signal and the low order bit value of digital signal just constitute the high accuracy number output Dout of conversion through numerical digit sign indicating number synthesizer 108 synthetic backs.
Though existing this analog switch method of fractional steps A/D converter does not need high-speed d/a transducer and high speed analog quantity subtracter, operating rate obtains bigger raising, and manufacture difficulty descends to some extent, and required precision resistance of this mode and analog switch quantity are bigger.And the making of precision resistance takies bigger chip area, and the many backs of analog switch quantity line complexity has increased the making complexity, thereby the high-precision a/d converter of making this mode is still brought certain difficulty simultaneously.
Summary of the invention
In order to overcome the above-mentioned defective of prior art, the invention provides a kind of A/D converter that can reduce precision resistance and analog switch quantity in a large number and reduce high speed with the high-precision analog switch method of fractional steps of chip manufacturing difficulty.
A project of the present invention be to reduce the required precision resistance of analog switch method of fractional steps A/D converter and the quantity of analog switch in a large number, reduce the area that they take in chip, thereby reduce the manufacture difficulty of chip, the qualification rate of raising product also reduces cost.
Another object of the present invention is to use the unidirectional analog switch with the effect of being inserted into to guarantee the realization of high-speed and high-precision a/d converter in the A/D converter of the analog switch method of fractional steps.
In order to realize above-mentioned purpose of the present invention, analog switch method of fractional steps A/D converter of the present invention comprises: an input end of analog signal, a sampling hold circuit, a multi-component-level rough segmentation standard capacitance box, a rough segmentation component level voltage determining device, a high order digit encoder, an analog switch Strobe Controller, a multi-component-level fine graduated standard voltage generator, a segmentation component level voltage determining device, a low order bit encoder, a high and low numerical digit sign indicating number synthesizer and a digital signal output end.Multi-component-level rough segmentation standard capacitance box wherein has a high reference voltage input and a low reference voltage input, have by etc. the multiple component levels normal voltage output of component level difference alternation be connected with a plurality of corresponding rough segmentation component level normal voltage input of rough segmentation component level voltage determining device, contiguous per two normal voltage outputs are provided with a pair of analog switch and controlled by the gating of analog switch Strobe Controller, and two normal voltage inputs with multi-component-level fine graduated standard voltage generator are switched on or switched off simultaneously.The analog signal of input is transported to rough segmentation voltage determining device respectively with sampled level and is segmented the voltage determining device after input end of analog signal is transported to sampling hold circuit.Sampled level judges after comparing with multi-component-level rough segmentation normal voltage in rough segmentation component level voltage determining device, judge signal to high order digit code coder and analog switch Strobe Controller output rough segmentation component level voltage respectively then, the analog switch Strobe Controller is connected respectively with two normal voltage inputs of multi-component-level fine graduated standard voltage generator simultaneously according to the corresponding vicinity two normal voltage outputs of the multi-component-level rough segmentation standard capacitance box of judgement signal gating of rough segmentation component level voltage.Sampled level judges after comparing with multi-component-level segmentation criteria voltage from multi-component-level fine graduated standard voltage generator in segmentation component level voltage determining device, to low order bit encoder output segmentation component level judgement signal.After high low order bit sign indicating number synthesizer is synthetic, export high-precision digital signal by the high order digit sign indicating number of high order digit encoder output with by the low order bit sign indicating number of low order bit encoder output at digital signal output end.
The present invention needs prior art to be modified into two multi component level standard voltage generators of rough segmentation and segmentation of being made up of respectively a few components with the single multi component level standard voltage generator that a large amount of elements are formed.To carry out the required analog switch number of gating control to the segmentation determining device by the rough segmentation determining device only reduces to from many groups more than two groups and needs two groups.This has just compressed components and parts number and analog switch number in large quantities, has compressed chip area footprints and circuit scale.It can realize the more A/D converter of seniority top digit with same circuit scale.Even can realize the high-precision a/d converter that to realize under the prior art situation.
Description of drawings
For the clearer understanding to the present invention is provided, most preferred embodiment of the present invention is made detailed description below in conjunction with accompanying drawing.
Fig. 1 is the circuit diagram of existing analog switch method of fractional steps A/D converter.
Fig. 2 is the circuit diagram of the analog switch method of fractional steps A/D converter of one embodiment of the present invention.
Fig. 3 is the electrical block diagram of used analog switch in one embodiment of the present invention analog switch method of fractional steps A/D converter.
Embodiment
Fig. 2 illustrates the circuit schematic construction of the analog switch method of fractional steps A/D converter of one embodiment of the present invention.Multi component level standard voltage generator 202 wherein is that the precision resistance by a plurality of equivalences is composed in series, the two ends of series resistance are respectively just, and drawing of reference voltage meets end Vref1 and Vref2, draw a rough segmentation normal voltage output from per two adjacent precision resistance tie points, each is formed into right rough segmentation component level normal voltage output side by side through an analog switch again at the two ends of each precision resistance, and many control ends to analog switch arranged side by side are formed controlled by analog switch Strobe Controller 205 many to the gating control end; The rough segmentation component level voltage determining device 203 of this embodiment is made up of a plurality of comparators, be connected to an input of each comparator from the sampled level of sampling hold circuit 201, another input of each comparator inserts each the rough segmentation normal voltage that is inserted by rough segmentation standard capacitance box 202 respectively in regular turn, and the output of a plurality of comparators is formed a plurality of judgement outputs of rough segmentation component level voltage determining device 203; The multi-component-level fine graduated standard voltage generator 209 of this embodiment also is that the precision resistance by a plurality of equivalences is composed in series, the two ends of this series resistance are connected with each paired rough segmentation component level normal voltage output of multi-component-level rough segmentation standard capacitance box 202 respectively, and from then on a segmentation criteria voltage output end is drawn at the tie point place of per two adjacent precision resistances of series resistance; The structure of the segmentation component level voltage determining device 206 of this embodiment and the similar that aforementioned crude is divided component level voltage determining device 203.
Fig. 3 shows the used circuit schematic construction that can reduce the unidirectional isolation analog switch that inserts effect in one embodiment of the present invention analog switch method of fractional steps A/D converter.It by the first NPN transistor T3, the second NPN transistor T4, a PNP transistor T 2, the 2nd PNP transistor T 2 ', the 3rd PNP transistor T 1 totally five transistors form.The one PNP transistor T 2 and PNP transistor T 2 ' emitter and collector link to each other respectively, PNP transistor in parallel partners, two transistorized base stages in a pair of PNP transistor in parallel can be elected to be the input end of analog signal Vi and the input control end Vc of analog switch respectively, the base stage of the first NPN transistor T3 links to each other with the tie point of the transistorized emitter of PNP of described a pair of parallel connection, the emitter of the first NPN transistor T3 is then as the output end vo of analog switch, the collector electrode of the first NPN transistor T3 connects reference voltage Vcc, the emitter of NPN transistor T4 links to each other with the PNP transistor T 2 of parallel connection and the collector electrode tie point of T2 ', and be connected to power supply " ".NPN transistor T4 base stage connects the first bias voltage Vb1, the collector electrode of the 3rd PNP transistor T 1 links to each other with collector electrode with the base stage of the first NPN transistor T3 respectively with base stage, the collector electrode of the 3rd PNP transistor T 1 links to each other with collector electrode with the base stage of the first NPN transistor T3 respectively with base stage, and the emitter of the 3rd PNP transistor T 1 connects the second bias voltage Vb2.
The ruuning situation of used analog switch is that the input signal on the Vi is sealed, and can't be sent to output, the output output low level when the control signal of control end Vc is " 0 " (during low level) among embodiment of the invention described above.When the control signal of control end Vc is " 1 " (during high level), input signal on the Vi is through the 2nd PNP transistor T 2 ' follow output, signal level has improved an emitter junction pressure drop, follows output through the first NPN transistor T3 again, and signal level is recovered original value.Input signal is in change procedure, because the constant current effect of T1, T4 pipe, the electric current that flows through in T2 ', the T3 pipe is constant all the time, also is that transistorized emitter junction pressure drop is constant, makes that the signal after analog switch transmission of the present invention can not produce additional distortion.Because to the two-stage emitter following of input signal, the input impedance of switch is very high in the switch, the access of switch can not produce harmful plug-in effect to signal.The speed of this switch is exceedingly fast, and the propagation delay under the conventional manufacture craft by means of it, can ensure high speed of the present invention and high-precision conversion operation less than 1ns.
For used analog switch among embodiment of the invention described above is designed to be able to and the compatible circuit of conventional ambipolar NPN transistor integrated circuit technology, all PNP transistors all adopt the horizontal or vertical structure of making the base and being provided with along substrate level or depth direction with the N type semiconductor material in this embodiment of the present invention.
Following table contrasts for analog switch method of fractional steps A/D converter of the present invention and the existing analog switch method of fractional steps A/D converter quantity of required precision resistance and analog switch under the situation of different accuracy:
As seen from the above table, the present invention has reduced the quantity of precision resistance and analog switch in large quantities, very help realizing high-precision a/d converter, again because the unidirectional isolation analog switch that is adopted in the present invention is a kind of ten minutes device at a high speed, therefore, the present invention is a kind of high speed, high-precision a/d converter.
Claims (7)
1. a high speed, high-precision A/D converter, it is characterized in that it comprises: an input end of analog signal, a sampling hold circuit, a multi-component-level rough segmentation standard capacitance box, a rough segmentation component level voltage determining device, a high order digit encoder, an analog switch Strobe Controller, a multi-component-level fine graduated standard voltage generator, a segmentation component level voltage determining device, a low order bit encoder, a high and low numerical digit sign indicating number synthesizer and a digital signal output end; Wherein said multi-component-level rough segmentation standard capacitance box has a high reference voltage input and a low reference voltage input, have by etc. the multiple component levels normal voltage output of component level difference alternation be connected with a plurality of corresponding rough segmentation component level normal voltage input of described rough segmentation component level voltage determining device, contiguous per two described rough segmentation component level normal voltage outputs are provided with a pair of analog switch and controlled by the gating of described analog switch Strobe Controller, and two normal voltage inputs with described multi-component-level fine graduated standard voltage generator are switched on or switched off simultaneously; The analog signal of input is transported to sampled level respectively described rough segmentation voltage determining device and described segmentation voltage determining device after described input end of analog signal is transported to described sampling hold circuit, sampled level judges after comparing with multi-component-level rough segmentation normal voltage in described rough segmentation component level voltage determining device, then judge signal to described high order digit code coder and described analog switch Strobe Controller output rough segmentation component level voltage respectively, described analog switch Strobe Controller is connected respectively with two described normal voltage inputs of described multi-component-level fine graduated standard voltage generator simultaneously according to the corresponding vicinity two described normal voltage outputs of the described multi-component-level rough segmentation standard capacitance box of judgement signal gating of rough segmentation component level voltage, sampled level judges after comparing with multi-component-level segmentation criteria voltage from described multi-component-level fine graduated standard voltage generator in described segmentation component level voltage determining device, judge signal to described low order bit encoder output segmentation component level, after described high low order bit sign indicating number synthesizer is synthetic, export high-precision digital signal at described digital signal output end by the high order digit sign indicating number of described high order digit encoder output with by the low order bit sign indicating number of described low order bit encoder output.
2. according to the described high speed of claim 1, high-precision A/D converter, it is characterized in that, wherein said multi component level standard voltage generator is composed in series by the precision resistance of a plurality of equivalences, it is high that the two ends of described series resistance are respectively, low drawing of reference voltage connects end, draw a described rough segmentation normal voltage output from per two adjacent described precision resistance tie points, each is formed into right described rough segmentation component level normal voltage output side by side through an analog switch again at the two ends of each described precision resistance, and many control ends to described analog switch arranged side by side are formed controlled by described analog switch Strobe Controller many to the gating control end.
3. according to the described high speed of claim 1, high-precision A/D converter, it is characterized in that, described rough segmentation component level voltage determining device is made up of a plurality of comparators, be connected to an input of each described comparator from the sampled level of described sampling hold circuit, another input of each described comparator inserts each the rough segmentation normal voltage that is inserted by described rough segmentation standard capacitance box respectively in regular turn, and the output of a plurality of described comparators is formed a plurality of judgement outputs of described rough segmentation component level voltage determining device.
4. according to the described high speed of claim 1, high-precision A/D converter, it is characterized in that, described multi-component-level fine graduated standard voltage generator is composed in series by the precision resistance of a plurality of equivalences, the two ends of described series resistance are connected with each paired described rough segmentation component level normal voltage output of described multi-component-level rough segmentation standard capacitance box respectively, draw a described segmentation criteria voltage output end from the tie point of per two adjacent described precision resistances of described series resistance.
5. according to the described high speed of claim 1, high-precision A/D converter, it is characterized in that, described segmentation component level voltage device is made up of a plurality of comparators, be connected to an input of each described comparator from the sampled level of described sampling hold circuit, another input of each described comparator inserts each the segmentation criteria voltage that is inserted by described fine graduated standard voltage generator respectively in regular turn, and the output of a plurality of described comparators is formed a plurality of judgement outputs of described segmentation component level voltage determining device.
6. according to the described high speed of claim 1, high-precision A/D converter, it is characterized in that, described analog switch is all respectively by first NPN transistor, second NPN transistor, the one PNP transistor, the 2nd PNP transistor, totally five transistors of the 3rd PNP transistor is formed, a wherein said PNP transistor links to each other respectively with the transistorized emitter and collector of described the 2nd PNP, PNP transistor in parallel partners, two transistor bases in the described a pair of PNP transistor in parallel are then respectively as the input end of analog signal of described analog switch and input control end, the base stage of described first NPN transistor links to each other with the transistorized emitter tie point of the PNP of described a pair of parallel connection, the emitter of described first NPN transistor is then as the output of described analog switch, the collector electrode of described first NPN transistor connects reference work voltage, the emitter of described second NPN transistor links to each other with the transistorized collector electrode tie point of the PNP of described a pair of parallel connection, and be connected to power supply " ", the collector electrode of described second NPN transistor links to each other with the output of described analog switch, the base stage of described second NPN transistor connects first bias voltage, the transistorized collector electrode of described the 3rd PNP links to each other with collector electrode with the base stage of described first NPN transistor respectively with base stage, and the transistorized emitter of described the 3rd PNP connects second bias voltage.
7. according to the described high speed of claim 6, high-precision A/D converter, it is characterized in that, wherein said first, second be the horizontal or vertical PNP transistor of in integrated circuit (IC) chip, making the base and being provided with the 3rd PNP transistor along substrate level or depth direction with the N mold base material of described chip.
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| CNA2007100645891A CN101272145A (en) | 2007-03-21 | 2007-03-21 | High-speed and high-precision A/D converter |
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| CN109976222A (en) * | 2019-04-16 | 2019-07-05 | 西安建筑科技大学 | A kind of SCM Based A/D acquisition method and device |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN109976222A (en) * | 2019-04-16 | 2019-07-05 | 西安建筑科技大学 | A kind of SCM Based A/D acquisition method and device |
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Open date: 20080924 |