Ukuba i-analog circuit (RF) kunye ne-digital circuit (microcontroller) zisebenza kakuhle ngabanye, kodwa xa ubeke ezimbini kwibhodi yesekethe efanayo kwaye usebenzise umbane ofanayo ukuze usebenze kunye, yonke inkqubo inokuthi ingazinzanga.Oku kungenxa yokuba umqondiso wedijithali ujingi rhoqo phakathi komhlaba kunye nonikezelo lwamandla olulungileyo (ubukhulu be-3 V), kwaye ixesha lifutshane kakhulu, ngokuphindaphindiweyo kwinqanaba le-ns.Ngenxa ye-amplitude enkulu kunye nexesha elincinci lokutshintsha, ezi zibonakaliso zedijithali ziqulethe inani elikhulu lamacandelo aphezulu axhomekeke kwi-frequency switching frequency.Kwinxalenye ye-analog, umqondiso osuka kwi-eriyali yokulungisa iluphu ukuya kwindawo yokufumana isixhobo esingenazingcingo ngokuqhelekileyo ungaphantsi kwe-1μV.
Ukwahlulwa okungonelanga kwemigca ebuthathaka kunye nemigca yemiqondiso enengxolo yingxaki rhoqo.Njengoko kukhankanyiwe ngasentla, imiqondiso yedijithali ine-swing ephezulu kwaye iqulethe inani elikhulu le-harmonics ye-high-frequency.Ukuba iingcingo zesignali yedijithali kwi-PCB ikufuphi neempawu ze-analog ezinovakalelo, ii-harmonics zefrikhwensi ephezulu zinokudityaniswa kwixesha elidlulileyo.Iindawo ezibuthathaka zezixhobo ze-RF zihlala ziyi-loop filter yesekethe ye-loop-lock loop (PLL), i-oscillator yangaphandle yombane elawulwayo (VCO) inductor, i-crystal reference signal kunye ne-antenna terminal, kwaye ezi ndawo zesekethe kufuneka ziphathwe. ngenkathalo ekhethekileyo.
Ekubeni igalelo / isignali yemveliso ine-swing ye-V emininzi, iisekethe zedijithali ziyamkeleka ngokubanzi kwingxolo yombane (ngaphantsi kwe-50 mV).Iisekethe ze-analog zinobuntununtunu kwingxolo yobonelelo lwamandla, ngakumbi kwii-voltages ze-burr kunye nezinye ii-harmonics eziphezulu.Ke ngoko, umzila wentambo yombane kwibhodi yePCB ene-RF (okanye enye i-analog) iisekethe kufuneka ilumke ngakumbi kunocingo olukwibhodi yesekethe yedijithali eqhelekileyo, kwaye umzila ozenzekelayo kufuneka uphetshwe.Kufuneka kwakhona kuqatshelwe ukuba i-microcontroller (okanye enye isekethe yedijithali) iya kutsala ngokukhawuleza kuninzi lwangoku ixesha elifutshane ngexesha lomjikelo wewotshi yangaphakathi, ngenxa yoyilo lwenkqubo yeCMOS yee-microcontrollers zanamhlanje.
Ibhodi ye-RF yesekethe kufuneka isoloko inomaleko womgca osezantsi oqhagamshelwe kwi-electrode engeyiyo yonikezelo lwamandla, enokuvelisa into ethile engaqhelekanga ukuba ayiphathwa kakuhle.Oku kunokuba nzima kumyili wesekethe yedijithali ukuqonda, kuba uninzi lweesekethe zedijithali zisebenza kakuhle nangaphandle komgangatho wokumisa.Kwibhendi yeRF, nokuba ucingo olufutshane lusebenza njenge-inductor.Ngokumalunga kubalwa, i-inductance nge-mm ubude malunga ne-1 nH, kunye ne-inductive reactive yomgca we-PCB we-10 mm kwi-434 MHz malunga ne-27 Ω.Ukuba umgangatho womhlaba awusetyenziswanga, imigca emininzi yomhlaba iya kuba yinde kwaye isiphaluka asiyi kuqinisekisa iimpawu zokuyila.
Oku kuhlala kungahoywa kwiisekethe eziqulethe amaza kanomathotholo kunye namanye amalungu.Ukongeza kwinxalenye yeRF, kuhlala kukho ezinye iisekethe ze-analog ebhodini.Ngokomzekelo, ii-microcontrollers ezininzi ziye zakha i-analog-to-digital converters (ADCs) ukulinganisa amagalelo e-analog kunye nombane webhetri okanye ezinye iiparamitha.Ukuba i-eriyali ye-RF ibekwe kufutshane (okanye) kule PCB, isignali ekhutshwayo yefrikhwensi ephezulu inokufikelela kwigalelo le-analog ye-ADC.Ungalibali ukuba nawuphi na umgca wesekethe unokuthumela okanye ufumane imiqondiso yeRF njengeeriyali.Ukuba igalelo le-ADC alilungiswanga kakuhle, isignali yeRF inokuzihlaziya kwigalelo le-ESD diode kwi-ADC, ibangele i-ADC itenxe.
Zonke izidibaniso kumgangatho womhlaba kufuneka zibe mfutshane ngokusemandleni, kwaye umhlaba nge-hole kufuneka ubekwe (okanye usondele kakhulu) ipadi yecandelo.Ungaze uvumele imiqondiso emibini yomhlaba ukuba yabelane ngomngxuma odlulayo, nto leyo enokubangela ukudibana phakathi kweepadi ezimbini ngenxa yoqhagamshelo lomngxunya.I-decoupling capacitor kufuneka ibekwe kufuphi nepini ngokusemandleni, kwaye i-capacitor decoupling kufuneka isetyenziswe kwipini nganye efuna ukuchithwa.Ukusebenzisa i-capacitors ye-ceramic ephezulu, uhlobo lwe-dielectric "NPO", "X7R" lusebenza kakuhle kwizicelo ezininzi.Ixabiso elifanelekileyo le-capacitance ekhethiweyo kufuneka ibe yinto yokuba uchungechunge lwayo lwe-resonance lulingana nomthamo wesignali.
Ngokomzekelo, kwi-434 MHz, i-SMD-efakwe kwi-100 pF capacitor iya kusebenza kakuhle, ngeli xesha, ukusabela kwe-capacitive ye-capacitor malunga ne-4 Ω, kunye ne-inductive reactance yomgodi kuluhlu olufanayo.I-capacitor kunye nomngxuma kwi-series yenza i-notch filter kwi-frequency yesignali, evumela ukuba idityaniswe ngokufanelekileyo.Kwi-868 MHz, i-33 p F capacitors lukhetho olufanelekileyo.Ukongeza kwi-RF edityanisiweyo yexabiso elincinci le-capacitor, i-capacitor yexabiso elikhulu kufuneka ibekwe kwintambo yombane ukuqhawula i-frequency ephantsi, ingakhetha i-2.2 μF ceramic okanye 10μF tantalum capacitor.
I-wiring yeenkwenkwezi yindlela eyaziwayo yoyilo lwesekethe ye-analog.Iingcingo zeenkwenkwezi - Imodyuli nganye ebhodini inomgca wayo wamandla ukusuka kwindawo yombane oqhelekileyo.Kule meko, ukudibanisa inkwenkwezi kuthetha ukuba iindawo zedijithali kunye neRF zesekethe kufuneka zibe neentambo zazo zombane, kwaye ezi ntambo zombane kufuneka ziqhawuke ngokwahlukeneyo kufutshane ne-IC.Oku kukwahlulwa kumanani
Indlela esebenzayo yengxolo engaphelelanga kunye nonikezelo lwamandla ukusuka kwinxalenye yeRF.Ukuba iimodyuli ezinengxolo enzima zibekwe kwibhodi enye, i-inductor (i-magnetic bead) okanye ukuchasana okuncinci (10 Ω) kunokudityaniswa kuluhlu phakathi komgca wamandla kunye nemodyuli, kunye ne-tantalum capacitor ubuncinane be-10 μF. kufuneka isetyenziswe njengokudityaniswa kombane kwezi modyuli.Iimodyuli ezinjalo ziyi-RS 232 abaqhubi okanye ukuguqula abalawuli bokunikezelwa kwamandla.
Ukuze kuncitshiswe ukuphazamiseka kwimodyuli yengxolo kunye nenxalenye ye-analog ejikelezileyo, ukulungiswa kwemodyuli yesiphaluka nganye ebhodini kubalulekile.Iimodyuli ezibuthathaka (iinxalenye ze-RF kunye nee-eriyali) kufuneka zihlale zigcinwe kude kwiimodyuli ezinomsindo (i-microcontrollers kunye nabaqhubi be-RS 232) ukuphepha ukuphazamiseka.Njengoko kukhankanyiwe ngasentla, iimpawu zeRF zinokubangela uphazamiseko kwezinye iimodyuli zesekethe ye-analog enjenge-ADCs xa zithunyelwa.Uninzi lweengxaki zenzeka kwiibhendi zokusebenza ezisezantsi (ezifana ne-27 MHz) kunye namanqanaba aphezulu emveliso yamandla.Luyilo olululo lokuziqhelisa ukuqhawula amanqaku abuthathaka ngeRF decoupling capacitor (100p F) eqhagamshelwe emhlabeni.
Ukuba usebenzisa iintambo ukudibanisa ibhodi yeRF kwisekethe yedijithali yangaphandle, sebenzisa iintambo ezijijekileyo.Intambo nganye yesignali kufuneka idityaniswe ngentambo ye-GND (DIN / GND, DOUT/ GND, CS/ GND, PWR _ UP/ GND).Khumbula ukudibanisa ibhodi yesekethe yeRF kunye nebhodi yesekethe yesicelo sedijithali kunye nentambo ye-GND yentambo ephothiweyo, kwaye ubude bentambo kufuneka bube bufutshane kangangoko.Ucingo olunika amandla ibhodi yeRF kufuneka lujijelwe nge-GND (VDD/ GND).
