Yog hais tias lub analog circuit (RF) thiab digital circuit (microcontroller) ua haujlwm zoo ib tus zuj zus, tab sis thaum koj muab ob qho tib si rau hauv tib lub rooj tsavxwm thiab siv tib lub zog los ua haujlwm ua ke, tag nrho cov kab ke yuav tsis ruaj khov.Qhov no feem ntau yog vim tias cov teeb liab digital nquag txav ntawm av thiab cov khoom siv hluav taws xob zoo (qhov loj 3 V), thiab lub sijhawm tshwj xeeb yog luv, feem ntau ns theem.Vim muaj qhov loj me me thiab lub sijhawm hloov me me, cov teeb liab digital no muaj cov khoom siv ntau zaus uas tsis muaj kev hloov pauv ntau zaus.Nyob rau hauv qhov analog, lub teeb liab los ntawm lub kav hlau txais xov tuning voj mus rau qhov tau txais ib feem ntawm lub wireless ntaus ntawv feem ntau tsawg dua 1μV.
Kev cais tsis txaus ntawm cov kab rhiab thiab cov kab teeb liab nrov yog qhov teeb meem tsis tu ncua.Raws li tau hais los saum no, cov teeb liab digital muaj lub viav vias siab thiab muaj ntau qhov sib txawv ntawm qhov sib txawv.Yog hais tias lub teeb liab digital thaiv ntawm PCB nyob ib sab ntawm cov teeb liab analog rhiab heev, kev sib raug zoo siab zaus yuav raug ua ke yav dhau los.Cov nodes rhiab heev ntawm RF cov khoom siv feem ntau yog lub voj lim lim ntawm lub voj voog lub voj voog (PLL), sab nraud voltage tswj oscillator (VCO) inductor, siv lead ua siv teeb liab thiab lub kav hlau txais xov davhlau ya nyob twg, thiab cov seem ntawm lub Circuit Court yuav tsum tau kho. nrog kev saib xyuas tshwj xeeb.
Txij li thaum lub tswv yim / tso zis teeb liab muaj lub viav vias ntawm ob peb V, cov kab hluav taws xob digital feem ntau siv tau rau lub suab nrov (tsawg dua 50 mV).Analog circuits yog rhiab heev rau lub hwj chim mov suab nrov, tshwj xeeb tshaj yog rau burr voltages thiab lwm yam high zaus harmonics.Yog li ntawd, cov kab hluav taws xob routing ntawm PCB pawg thawj coj saib uas muaj RF (los yog lwm yam analog) circuits yuav tsum tau ceev faj ntau dua li cov xaim ntawm lub rooj tsav xwm digital digital, thiab tsis siv neeg routing yuav tsum raug zam.Nws tseem yuav tsum tau muab sau tseg tias microcontroller (los yog lwm yam digital circuit) yuav dheev nqus nyob rau hauv feem ntau ntawm cov tam sim no rau ib lub sij hawm luv luv ntawm lub sij hawm nyob rau hauv txhua lub sij hawm nyob rau hauv lub moos, vim CMOS txheej txheem tsim ntawm niaj hnub microcontrollers.
Lub rooj tsav xwm RF yuav tsum ib txwm muaj cov kab hauv av txuas nrog rau qhov tsis zoo ntawm cov khoom siv hluav taws xob, uas yuav ua rau muaj qee qhov txawv txav yog tias tsis ua haujlwm zoo.Qhov no tej zaum yuav nyuaj rau tus tsim digital Circuit Court kom nkag siab, vim hais tias feem ntau cov digital circuits ua haujlwm zoo txawm tias tsis muaj txheej hauv av.Hauv RF band, txawm tias ib lub xov hlau luv luv ua zoo li inductor.Kwv yees kwv yees, qhov inductance ib hli ntev yog li 1 nH, thiab inductive reactance ntawm 10 hli PCB kab ntawm 434 MHz yog hais txog 27 Ω.Yog tias cov kab hauv av tsis siv, feem ntau cov kab hauv av yuav ntev dua thiab cov kab hluav taws xob yuav tsis lav cov yam ntxwv tsim.
Qhov no feem ntau tsis saib xyuas hauv circuits uas muaj xov tooj cua zaus thiab lwm qhov chaw.Ntxiv rau qhov RF feem, feem ntau muaj lwm yam analog circuits ntawm lub rooj tsavxwm.Piv txwv li, ntau lub microcontrollers muaj built-in analog-to-digital converters (ADCs) los ntsuas analog inputs nrog rau cov roj teeb voltage lossis lwm yam tsis.Yog hais tias RF transmitter lub kav hlau txais xov nyob ze (los yog ntawm) PCB no, lub teeb liab emission high-frequency yuav ncav cuag lub analog input ntawm ADC.Tsis txhob hnov qab tias txhua kab hluav taws xob tuaj yeem xa lossis tau txais RF signals zoo li lub kav hlau txais xov.Yog tias ADC cov tswv yim tsis ua tiav, RF teeb liab tuaj yeem ua rau nws tus kheej zoo siab hauv ESD diode input rau ADC, ua rau ADC sib txawv.
Tag nrho cov kev sib txuas rau hauv av txheej yuav tsum yog luv li sai tau, thiab hauv av los ntawm lub qhov yuav tsum tau muab tso rau (los yog ze heev rau) lub ncoo ntawm cov khoom.Tsis txhob cia ob lub hauv paus teeb liab sib qhia hauv av los ntawm lub qhov, uas tuaj yeem ua rau crosstalk ntawm ob lub ncoo vim qhov kev sib txuas ntawm lub qhov impedance.Lub decoupling capacitor yuav tsum muab tso rau ze li ntawm tus pin li sai tau, thiab capacitor decoupling yuav tsum tau siv ntawm txhua tus pin uas yuav tsum tau decoupled.Siv cov khoom siv hluav taws xob zoo tshaj plaws, cov dielectric hom yog "NPO", "X7R" kuj ua haujlwm zoo hauv ntau daim ntawv thov.Qhov zoo tshaj plaws tus nqi ntawm qhov kev xaiv capacitance yuav tsum yog xws li tias nws cov resonance series yog sib npaug rau lub teeb liab zaus.
Piv txwv li, ntawm 434 MHz, SMD-mounted 100 pF capacitor yuav ua haujlwm zoo, ntawm qhov zaus no, lub capacitive reactance ntawm lub capacitor yog li 4 Ω, thiab inductive reactance ntawm lub qhov yog nyob rau hauv tib qhov ntau.Lub capacitor thiab lub qhov nyob rau hauv series tsim ib tug notch lim rau lub teeb liab zaus, cia nws mus decoupled zoo.Ntawm 868 MHz, 33 p F capacitor yog qhov kev xaiv zoo tshaj plaws.Ntxiv nrog rau RF decoupled tus nqi me me capacitor, tus nqi loj capacitor yuav tsum tau muab tso rau ntawm lub hwj chim kab kom decouple qhov tsawg zaus, tuaj yeem xaiv 2.2 μF ceramic lossis 10μF tantalum capacitor.
Lub hnub qub thaiv yog cov txheej txheem paub zoo hauv kev tsim qauv analog.Lub hnub qub thaiv - Txhua qhov module ntawm lub rooj tsavxwm muaj nws tus kheej txoj kab hluav taws xob los ntawm cov khoom siv hluav taws xob sib txuas.Nyob rau hauv cov ntaub ntawv no, lub hnub qub thaiv txhais tau hais tias cov digital thiab RF qhov chaw ntawm lub Circuit Court yuav tsum muaj lawv tus kheej lub hwj chim kab, thiab cov hwj chim kab yuav tsum tau muab cais cais nyob rau hauv lub IC.Qhov no yog kev sib cais los ntawm cov lej
Ib txoj hauv kev zoo rau ib nrab thiab lub hwj chim muab suab nrov los ntawm RF feem.Yog hais tias cov modules uas muaj suab nrov heev raug muab tso rau ntawm tib lub rooj tsavxwm, lub inductor (magnetic hlaws) los yog me me kuj tsis kam (10 Ω) tuaj yeem txuas rau hauv series ntawm cov kab hluav taws xob thiab cov module, thiab tantalum capacitor tsawg kawg yog 10 μF. yuav tsum tau siv raws li lub hwj huam mov decoupling ntawm cov modules.Xws li modules yog RS 232 tsav tsheb los yog hloov fais fab mov regulators.
Txhawm rau txo qhov cuam tshuam los ntawm lub suab nrov module thiab qhov chaw nyob ib puag ncig analog, qhov kev teeb tsa ntawm txhua qhov module ntawm lub rooj tsavxwm yog qhov tseem ceeb.Cov modules rhiab heev (RF qhov chaw thiab kav hlau txais xov) yuav tsum nyob deb ntawm cov suab nrov (microcontrollers thiab RS 232 tsav tsheb) kom tsis txhob cuam tshuam.Raws li tau hais los saum no, RF teeb liab tuaj yeem ua rau cuam tshuam rau lwm cov khoom siv hluav taws xob analog hluav taws xob xws li ADCs thaum lawv xa.Feem ntau cov teeb meem tshwm sim nyob rau hauv qis kev khiav hauj lwm bands (xws li 27 MHz) raws li zoo raws li siab zog tso zis ntau ntau.Nws yog ib qho kev tsim qauv zoo rau decouple rhiab cov ntsiab lus nrog RF decoupling capacitor (100p F) txuas rau hauv av.
Yog tias koj siv cov cables los txuas lub RF board mus rau ib qho digital circuit sab nraud, siv twisted-pair cables.Txhua lub teeb liab cable yuav tsum tau twinned nrog GND cable (DIN / GND, DOUT / GND, CS / GND, PWR _ UP / GND).Nco ntsoov txuas lub RF Circuit Court board thiab daim ntawv thov digital Circuit Board nrog GND cable ntawm twisted-pair cable, thiab lub cable ntev yuav tsum luv li sai tau.Cov kab hluav taws xob uas ua rau lub rooj tsav xwm RF kuj yuav tsum tau sib tw-nrog GND (VDD / GND).
