General hauv paus ntsiab lus ntawm cov lag luam ntawm ADC

Cia saib lub ntsiab ntau yam ntawm cov teeb meem uas yuav tsum tau ntaus nqi mus rau lub hauv paus ntsiab lus ntawm cov analog-rau-digital converters (ADCs) muaj ntau hom. Tshwm Sim Los Muaj account, successive balancing - li cas nta qab tej lus no? Yuav ua li cas yog cov ua hauj lwm hauv paus ntsiab lus ntawm cov ADC ntawm lub microcontroller? No thiab lwm yam teeb meem yuav tsum tau tham nyob rau hauv lub moj khaum ntawm qhov tsab xov xwm. Thawj peb yuav tsum mob siab rau cov kev tshawb xav, thiab plaub subtitle yuav kawm yuav ua li cas lawv ua hauj lwm. Koj muaj peev xwm ua tau raws li ntau yam ntaub ntawv ADC thiab DAC cov ntsiab lus uas. Lub hauv paus ntsiab lus ntawm cov lag luam ntawm cov pab kiag li lawm yog me ntsis txawv, yog li ntawd tsis txhob xav yuam kev rau lawv. Yog li, hauv tsab xov xwm yuav tsum tau suav hais tias yog hloov dua siab tshiab ntawm Pib ntsais koj teeb ntawm analog rau digital, thaum lub DAC ua hauj lwm nyob rau hauv rov qab.

txhais

Ua ntej xav tias cov hauv paus ntsiab lus ntawm cov ADC, cia peb kawm seb yog dab tsi lub ntaus ntawv yog. Analog rau cov converters yog pab kiag li lawm tias lub cev muaj nuj nqis yog hloov dua siab tshiab rau hauv ib tug coj numeric sawv cev. Cov thawj zaug parameter yuav ua yuav luag txhua yam - tam sim no, voltage, capacitance, kuj, kev sib hloov ntawm tus ncej, cov mem tes dhia thiab thiaj li nyob. Tab sis nyob rau hauv thiaj li yuav muaj tseeb, peb yuav ua hauj lwm nrog tsuas yog ib hloov dua siab tshiab. Qhov no "code voltage". Qhov kev xaiv ntawm no ua hauj lwm hom ntawv yog tsis lo. Tom qab lub ADC (lub hauv paus ntsiab lus ntawm cov lag luam ntawm no ntaus ntawv) thiab nws cov nta yog lom zem ntau nyob rau dab tsi zoo ntawm kev ntsuas tswvyim yog siv. Qhov no yog hais txog cov txheej txheem kev piv ib yam nqi nrog ib tug yav tas los tsim tus qauv.

yam ntxwv ADC

Lub ntsiab me ntsis yuav yog hu ua, thiab conversion tus nqi. Thawj qhia nyob rau hauv me me, thiab lub thib ob - nyob rau hauv kuaj ib tug thib ob. Niaj hnub nimno analog-rau-digital converters yuav muaj 24-ntsis los yog cov hloov dua siab tshiab ceev, uas los rau GSPS units. Nco ntsoov tias lub ADC yuav ib txhij muab koj nrog rau cov kev siv cov tsuas yog ib qho ntawm nws cov yam ntxwv. Qhov ntau dua lawv cov kev kawm, qhov ntau nyuaj ua hauj lwm nrog lub ntaus ntawv, thiab nws yog kim kim nws tus kheej. Tab sis cov kev pab tej zaum yuav mus tau tus tsim nyog me ntsis tob kev kawm los ntawm kev txi cov kev ceev ntawm lub twj paj nruag.

ADC hom

Hauv paus ntsiab lus ntawm cov lag luam mas nws txawv cov sib txawv pab pawg ntawm cov pab kiag li lawm. Peb xav txog cov nram hom:

1. Txij li thaum direct hloov dua siab tshiab.
2. Nrog successive approximation.
3. Nrog ib tug thaum uas tig mus pom.
4. Analog-rau-digital converter nrog ib tug balancing xwb (raws-sigma).
5. Ua ke ADC.

Muaj ntau ntau lwm yam conveyor thiab ua ke, uas muaj lawv tus kheej tshwj xeeb cov yam ntxwv sib txawv ntawm cov architecture. Tab sis cov neeg kuaj, uas yuav muab suav hais tias nyob rau hauv lub moj khaum ntawm cov khoom yog paj vim hais tias lawv ua si ib tug yam ntxwv lub luag hauj lwm nyob rau hauv nws me me pab kiag li lawm xws things. Yog li ntawd cia peb kawm lub hauv paus ntsiab ntawm lub ADC, raws li zoo raws li nws cov dependence rau lub cev ntaus ntawv.

Direct analog rau cov converters

Lawv tau ua heev nrov nyob rau hauv lub 60-70-ies ntawm lub xeem caug xyoo. Nyob rau hauv daim ntawv ntawm cov kev circuits yog ua nrog 80s. Nws yog yooj yim heev, txawm txheej thaum ub pab kiag li lawm uas yuav tsis khav ntawm tseem ceeb cov nuj nqis. Lawv muaj peev xwm yog feem ntau 6-8 me me, thiab cov kev ceev tsis tshua tshaj 1 GSPS.

Lub hauv paus ntsiab lus ntawm cov lag luam ntawm no hom ntawm ADC yog tias nyob rau hauv ntxiv inputs ntawm comparators tswv yim teeb liab ib txhij. Nyob rau qhov tsis zoo davhlau ya nyob twg voltage yog ib tug tej yam muaj nuj nqis. Thiab ces tus ntaus ntawv txiav txim nws lub lag luam. Qhov no yog ua tsaug rau cov kev siv voltage. Cia peb xav hais tias peb muaj ib tug ntaus ntawv rau qhov twg 8 comparators. Thaum pub ½ ntawm cov kev siv voltage yog enabled xwb 4 ntawm lawv. Qhov muaj feem thib encoder tsim binary code, uas yog tso zis register thiab latches. Tus kwv tij strengths and weaknesses yuav hais tias qhov no paus ntsiab lus ntawm lub lag luam tso cai rau koj los mus tsim high-ceev kiag li lawm. Tab sis kom txais tau lub yuav tsum tau lo lus ntev muaj hws ntau.

Cov kev mis rau tus xov tooj ntawm comparators yog raws li nram no: 2 ^ N. Nyob rau hauv N yog tsim nyog los muab tso rau hauv lub xov tooj ntawm tug lej tom qab. Saib yav dhau los piv txwv li yuav siv tau dua: 2 ^ 3 = 8. Subtotal rau peb paug yuav tsum 8 comparators. Qhov no yog lub ntsiab cai ntawm lub ADC, uas tau raug tsim ua ntej. Tsis yooj yim heev, li ntawd, tom qab muaj lwm yam architecture.

Analog-rau-digital converters, successive approximation

algorithm "weighting" yog siv no. Luv zog pab kiag li lawm kev khiav hauj lwm nyob rau hauv xws li ib tug txheej txheem, xa mus rau cias li ADC successive cov nqi kho mob. Lub hauv paus ntsiab lus ntawm cov lag luam yog raws li nram no: lub ntaus ntawv yog ntsuas los ntawm lub tswv yim teeb liab, thiab ces nws yuav muab piv nrog rau cov xov tooj, uas yog generated raws li ib tug tej yam txheej txheem:

1. Poob lawm tau ib nrab ntawm cov reference voltage.
2. Yog hais tias lub teeb liab magnitude txwv kov yeej txawv tebchaws №1, nws yog muab piv nrog ib tug xov tooj uas dag midway ntawm lub tshuav nqi. Yog li ntawd, nyob rau hauv peb cov ntaub ntawv nws yuav ¾ ntawm tus siv voltage. Yog hais tias cov kev siv lub teeb liab ntog luv luv ntawm no daim duab, cov kev sib piv yuav tsum tau ua nrog rau lwm tus feem ntawm lub luv los ntawm tib lub hauv paus ntsiab lus. Nyob rau hauv qhov kev piv txwv, ¼ ntawm cov kev siv voltage.
3. Kauj ruam 2 yuav tsum tau rov qab n lub sij hawm, uas yuav muab rau peb lub N khoom ntawm lub txiaj ntsim. Qhov no yog vim tus cwj pwm ntawm N tooj ntawm kev sib piv.

Qhov no txoj ntsiab cai ntawm cov apparatus tso cai rau kom muab tau nrog tus kwv tij siab hloov dua siab tshiab tus nqi, uas yog successive approximation ADCs. Lub hauv paus ntsiab lus ntawm lub lag luam, raws li koj tau pom, yooj yim, thiab cov pab kiag li lawm yog zoo tagnrho rau ntau yam ntawm lub sij hawm ntawd.

Parallel analog-rau-digital converters

Lawv ua hauj lwm zoo li ib tug serial ntaus ntawv. Muab xam los mis - (2 ^ n) -1. Rau cov ntaub ntawv xam tau tias yog yav tas los, peb yuav tsum tau (2 ^ 3) -1 comparators. Rau cov lag luam siv ib lub array ntawm cov pab kiag li lawm, txhua tus uas yuav piv tau rau cov tswv yim thiab ib tug neeg siv voltage. Parallel analog-rau-digital converters yog haum ceev ceev kiag li lawm. Tab sis lub ntsiab cai ntawm kev tsim kho ntawm cov pab kiag li lawm yog tias los pab txhawb lawv efficiency yuav tsum tau tseem ceeb lub hwj chim. Yog li ntawd, lawv siv nyob rau hauv roj teeb powered tsis tsim nyog.

Analog-rau-digital converter nrog successive balancing

Nws ua hauj lwm nyob rau hauv ib txoj kev zoo raws li lub yav dhau los ntaus ntawv. Yog li ntawd, nyob rau hauv thiaj li yuav piav qhia txog lub lag luam los ntawm successive balancing ADC, lub hauv paus ntsiab lus ntawm cov lag luam rau cov beginners yuav muab suav hais tias cia rau cov ntiv tes. Nyob rau hauv cov pab kiag li lawm raws li nyob rau tshwm sim ntawm lub dichotomy. Nyob rau hauv lwm yam lus, lub serial sib piv yog nqa tawm ntsuas nqi nrog ib tug tej ib feem ntawm lub siab tshaj plaws muaj nqis. Yuav muab qhov tseem ceeb ½, 1/8, 1/16 thiab thiaj li nyob. Yog li ntawd, analog-rau-digital converter yuav ua tau tus txheej txheem rau N iterations (successive cov kauj ruam). Wherein N sib npaug lub ntsis ADC (saib cov yav tas los saum toj no cov qauv). Yog li, peb muaj ib tug txiav txim nce nyob rau hauv lub sij hawm, yog hais tias nws yog tshwj xeeb tshaj yog ib qho tseem ceeb kawm cov txheej txheem. Dua li ntawm qhov loj ceev, cov pab kiag li lawm yog tseem yus muaj los ntawm cov uas tsis muaj zoo li qub yuam kev.

Analog-rau-digital converters nrog xwb ntsuas (delta-sigma)

Nws yog lub feem ntau nthuav yam ntaus ntawv, tsis yog tsawg kawg vim nws khiav hauj lwm hauv paus ntsiab lus. Nws muaj nyob rau hauv hais tias lub tswv yim voltages piv li hais tias cov sau integrator. Yog cov tswv yim pulses nrog ib tug tsis zoo los yog zoo polarity (nws nyob rau hauv no yav dhau los lub lag luam). Yog li, peb yuav hais tias xws li ib tug analog-rau-digital converter yog ib tug yooj yim mus txog qhovtwg system. Tab sis qhov no yog ib qho piv txwv rau kev sib piv, ces koj yuav to taub li cas cov delta-sigma ADC. Hauv paus ntsiab lus ntawm cov lag luam system, tab sis rau cov zoo lag luam ntawm lub analog-rau-digital converter yog tsis txaus. Qhov kawg no yog ib qho kev txom kwj ntawm cov laug thiab zeros, uas mus los ntawm ib cov tsawg-pass lim. Lawv tsim ib tug tej yam me ntsis ib theem zuj zus. Paub qhov txawv ADC converters ntawm tus thawj thiab thib ob kev txiav txim.

Ua ke analog-rau-digital converter

Qhov no yog ib tug tshwj xeeb cov ntaub ntawv ntawm lub yav tas, uas yuav muab suav hais tias raws li ib feem ntawm qhov tsab xov xwm. Tom ntej no, peb yuav piav qhia txog lub lag luam los ntawm cov pab kiag li lawm, tab sis rau ib qho lawm. Qhov no ADC yog analog-rau-digital converter nrog laub-rub ua ke. Yuav kom tau raws li ib tug ntaus ntawv yuav ua tau ib cov multimeter. Thiab qhov no yog vim li, vim hais tias lawv muab siab raug thiab nyob rau tib lub sij hawm zoo suppress cuam.

Tam sim no cia tus siab rau nws cov hauv paus ntsiab lus ntawm lub lag luam. Nws cov lus dag nyob rau hauv lub fact tias lub tswv yim capacitor yog them rau ib tug taag lub sij hawm. Feem ntau, qhov no lub sij hawm yog ib tug ntawm cov mains zaus uas powers tus ntaus ntawv (50 Hz los yog 60 Hz). Nws kuj yuav muaj ntau yam. Yog li, high-zaus suab nrov yog suppressed. Ib txhij leveled cawv tsis ruaj tsis khov voltage hwj chim qhov twg los ntawm hluav taws xob rau cov neeg ntawm cov kev tshwm sim.

Thaum tus nqi lub sij hawm xaus analog-digital converter, lub capacitor pib tawm nrog ib tug taag ceev. Internal counter ntaus ntawv suav tus xov tooj ntawm moos pulses uas yog generated thaum lub sij hawm tus txheej txheem no. Yog li, ntev lub sij hawm luv, ntau dua qhov kev ua tau zoo.

ADC twostroke kev koom ua ke muaj siab raug thiab daws teeb meem. Vim rau qhov no, raws li zoo raws li qhov kev siv ntawm ib tug kuj yooj yim qauv, lawv yuav tua raws li ib tug nti. Lub ntsiab drawback ntawm xws li ib tug hauv paus ntsiab lus ntawm kev ua hauj lwm - nyob ntawm seb qhov kev kawm network. Nco ntsoov hais tias nws muaj peev xwm yog khi rau lub duration ntawm lub zaus fais fab mov sij hawm.

Ntawm no yog yuav ua li cas lub ADC ob koom ua ke. Lub hauv paus ntsiab lus ntawm cov lag luam ntawm tus dais txawm tias nws yog heev, tab sis nws muab qhov zoo tshaj ntsuas. Nyob rau hauv tej rooj plaub, qhov no yog tsuas indispensable.

Xaiv APC rau peb nrog cov uas tsim nyog hauv paus ntsiab lus ntawm

Wb hais tias, peb yuav ntsib nrog ib tug kev ua hauj lwm. Uas xaiv lub ntaus ntawv thiaj li hais tias nws ua tau raws li tag nrho cov ntawm peb xav tau kev pab? Ua ntej, peb tham txog cov kev daws teeb meem thiab raug. Heev feem ntau lawv feeb tsis meej, txawm hais tias nyob rau hauv xyaum lawv yog heev weakly nyob rau lub thib ob ib. Nco ntsoov hais tias 12-ntsis analog-rau-digital converter tej zaum yuav tsawg tseeb tshaj 8-ntsis. Nyob rau hauv cov ntaub ntawv no, daws teeb meem - yog ib qho kev ntsuas ntawm tus kom muaj nuj nqis ntawm feem yuav muab sau ua ke rau lub measured teeb liab tswv yim ntau yam. Yog li, 8-ntsis ADC muaj yim hli ntuj ² = 256 xws units.

Raug - yog tag nrho cov hloov dua siab tshiab tshwm sim tau txawv los ntawm cov zoo tagnrho qhov tseem ceeb, uas yuav tsum nyob ib tug muab tswv yim voltage. Hais tias yog, tus thawj parameter characterizes lub peev xwm uas muaj lub ADC, thiab lub thib ob qhia tau hais tias yog dab tsi peb muaj nyob rau hauv xyaum. Yog li ntawd, peb yuav nce ntaiv thiab ntau yooj yim hom (piv txwv li, ncaj analog-rau-digital converters), uas yuav ua tau raws li cov uas yuav tsum tau vim nws cov high raug.

Yuav kom muaj ib lub tswv yim dab tsi nws yuav siv sij hawm mus pib xam lub cev tsis thiab tsim ib tug lej mis ntawm kev sis raug zoo. Tseem ceeb lawv yog zoo li qub thiab dynamic uas tsis, vim hais tias thaum uas siv cov ntau yam thiab tej ntsiab cai ntawm kev tsim kho ntawm lub ntaus ntawv lawv yuav muaj ib tug txawv tej yam nyob rau hauv nws cov kev ua tau zoo. Yog xav paub ntaub ntawv muaj nyob rau hauv cov kev cov ntaub ntawv uas muab los ntawm lub chaw tsim tshuaj paus ntawm txhua kev ntaus ntawv.

Piv txwv li

Cia saib cov ADC SC9711. Cov kev khiav hauj lwm hauv paus ntsiab lus ntawm no ntaus ntawv yog txoj vim hais tias ntawm nws loj thiab muaj peev xwm. Hais lus ntawm lub yav tas, nws yuav tsum tau muab sau tseg hais tias lawv yog tiag tiag muaj ntau haiv neeg. Yog li, piv txwv li, tej zaum cov lag luam zaus mas nws txawv ntawm 10 Hz mus rau 10 MHz. Nyob rau hauv lwm yam lus, nws yuav ua 10 lab kuaj ib ob! Thiab tus ntaus ntawv nws tus kheej tsis yog ib yam dab tsi tau, thiab muaj ib tug modular siv cov qauv. Tab sis nws yog feem ntau yog siv nyob rau hauv txoj daim ntaub ntawv twg koj yuav tsum tau mus ua hauj lwm nrog ib tug loj tus naj npawb ntawm Pib ntsais koj teeb.

xaus

Raws li koj tau pom, ADCs inherently muaj ntau cov ntsiab cai ntawm lub lag luam. Qhov no tso cai rau peb xaiv lub ntaus ntawv uas yuav los siav tsob xav tau kev pab thiab yog li cia tsim nyog siv muaj cov kev pab.