Lapha, izici ezine eziyisisekelo zamasekhethi efrikhwensi yomsakazo zizohunyushwa ezicini ezine: isixhumi esibonakalayo sefrikhwensi yomsakazo, isignali encane efiselekayo, isignali enkulu yokuphazamiseka, nokuphazamiseka kwesiteshi esiseduze, kanye nezici ezibalulekile ezidinga ukunakwa okukhethekile kunqubo yokuklama ye-PCB zinikezwa.
Isixhumi esibonakalayo serediyo yefrikhwensi yokulingisa isekethe yomsakazo
I-wireless transmitter nomamukeli zihlukaniswe ngokomqondo zibe izingxenye ezimbili: i-base frequency kanye nefrikhwensi yomsakazo.Ifrikhwensi eyisisekelo ihlanganisa ububanzi befrikhwensi yesiginali yokufaka yesidluliseli kanye nobubanzi bemvamisa yesiginali yokuphumayo yomamukeli.I-bandwidth yefrikhwensi eyisisekelo inquma izinga eliyisisekelo idatha engageleza ngayo ohlelweni.Imvamisa yesisekelo isetshenziselwa ukuthuthukisa ukuthembeka kokusakazwa kwedatha nokunciphisa umthwalo obekwe umthumeli endaweni yokudlulisela ngaphansi kwezinga elithile lokudlulisa idatha.Ngakho-ke, ulwazi oluningi lobunjiniyela bokucutshungulwa kwesignali luyadingeka lapho uklama isekethe yefrikhwensi eyisisekelo ku-PCB.Umjikelezo wefrikhwensi yomsakazo we-transmitter ungaguqula futhi uguqule isignali ye-baseband ecutshunguliwe ibe isiteshi esiqokiwe, futhi ijove lesi siginali endaweni yokudlulisela.Ngokuphambene, isekethe yefrikhwensi yomsakazo yomamukeli ingathola isignali endaweni yokudlulisela, futhi iguqule futhi inciphise ifrikhwensi ibe isizinda.
I-Transmitter inezinjongo ezimbili eziyinhloko zokuklama i-PCB: Eyokuqala ukuthi kufanele idlulisele amandla athile kuyilapho idla amandla amancane kakhulu.Okwesibili ukuthi abakwazi ukuphazamisa ukusebenza okuvamile kwama-transceivers eziteshini eziseduze.Ngokuqondene nomamukeli, kunemigomo emithathu yokuklama ye-PCB eyinhloko: okokuqala, kufanele abuyisele ngokunembile amasignali amancane;okwesibili, kufanele bakwazi ukususa izimpawu eziphazamisayo ngaphandle kwesiteshi abasifunayo;futhi okokugcina, njenge-transmitter, kumele badle amandla Mancane kakhulu.
Isignali enkulu yokuphazamiseka kokulingiswa kwesekhethi yomsakazo
Umamukeli kufanele azwele kakhulu kumasignali amancane, ngisho nalapho kunezimpawu ezinkulu zokuphazamiseka (izithiyo).Lesi simo senzeka lapho uzama ukuthola isignali yokudlulisela ebuthakathaka noma yebanga elide, futhi isidlulisi esinamandla esiseduze sisakaza esiteshini esiseduze.Isiginali ephazamisayo ingaba nkulu ngo-60 kuya ku-70 dB kunesiginali elindelekile, futhi ingambozwa ngenani elikhulu phakathi nesigaba sokufaka somamukeli, noma umamukeli angakwazi ukudala umsindo owedlulele phakathi nesigaba sokufaka ukuze avimbe ukwamukela amasignali avamile. .Uma umamukeli eshayelwa endaweni engeyona yomugqa umthombo wokuphazamiseka phakathi nesigaba sokufaka, izinkinga ezimbili ezingenhla zizokwenzeka.Ukuze ugweme lezi zinkinga, isiphetho sangaphambili somamukeli kufanele sibe nomugqa omkhulu.
Ngakho-ke, “umugqa” nawo uwukucatshangelwa okubalulekile ekwakhiweni kwe-PCB komamukeli.Njengoba umamukeli kuyisekethe ye-narrowband, i-nonlinearity ikalwa ngokulinganisa "i-intermodulation distortion".Lokhu kuhilela ukusebenzisa amagagasi e-sine amabili noma amagagasi e-cosine anamaza afanayo futhi atholakala kubhendi emaphakathi ukushayela isignali yokufaka, bese kulinganiswa umkhiqizo wokunqamuka kwayo.Ngokuvamile, i-SPICE iyisofthiwe yokulingisa edla isikhathi futhi ebiza kakhulu, ngoba kufanele yenze izibalo eziningi ze-loop ukuze ithole isixazululo esidingekayo ukuze kuqondwe ukuhlanekezela.
Isiginali encane elindelwe ekufanisweni kwesekethe ye-RF
Umamukeli kufanele azwele kakhulu ukuze abone amasignali amancane okokufaka.Ngokuvamile, amandla okufaka omamukeli angaba mancane njengo-1 μV.Ukuzwela komamukeli kunqunyelwe umsindo okhiqizwa isekethe yokufaka.Ngakho-ke, umsindo uwukucatshangelwa okubalulekile ekwakhiweni kwe-PCB yomamukeli.Ngaphezu kwalokho, ikhono lokubikezela umsindo ngamathuluzi okulingisa abalulekile.Umfanekiso 1 umamukeli ojwayelekile we-superheterodyne.Isignali etholiwe ihlungwa kuqala, bese isignali yokufaka ikhuliswa isikhulisi somsindo ophansi (LNA).Bese usebenzisa i-oscillator yendawo yokuqala (LO) ukuze uxube nalesi siginali ukuze uguqule lesi siginali ibe imvamisa emaphakathi (IF).Ukusebenza komsindo wesekethe yangaphambili ikakhulukazi kuncike ku-LNA, i-mixer ne-LO.Nakuba ukuhlaziya kwendabuko komsindo we-SPICE kungathola umsindo we-LNA, akusizi ku-mixer ne-LO, ngoba umsindo kulawa mabhulokhi uzothinteka kakhulu isignali ye-LO enkulu.
Isignali encane yokufaka idinga ukuthi umamukeli abe nomsebenzi omkhulu wokukhulisa, futhi ngokuvamile udinga ukuzuza okungu-120 dB.Ngenzuzo ephezulu kangako, noma iyiphi isignali ehlanganiswe kusukela ekugcineni kokuphumayo ibuyele ekugcineni kokufakwayo ingase ibangele izinkinga.Isizathu esibalulekile sokusebenzisa i-superheterodyne receiver architecture ukuthi ingasabalalisa inzuzo kumafrikhwensi ambalwa ukuze kuncishiswe ithuba lokuhlanganisa.Lokhu futhi kwenza imvamisa ye-LO yokuqala ihluke emvamisa yesiginali yokufaka, engavimbela amasiginali amakhulu okuphazamisa ukuba "angcoliswe" kuya kumasignali amancane okokufaka.
Ngezizathu ezahlukene, kwezinye izinhlelo zokuxhumana ezingenazintambo, ukuguqulwa okuqondile noma i-homodyne architecture ingathatha indawo ye-superheterodyne architecture.Kulesi sakhiwo, isignali yokufaka ye-RF iguqulwa ngokuqondile ibe imvamisa eyisisekelo ngesinyathelo esisodwa.Ngakho-ke, inzuzo enkulu imvamisa eyisisekelo, futhi imvamisa ye-LO kanye nesiginali yokufaka iyafana.Kulesi simo, umthelela wenani elincane lokuhlanganisa kufanele uqondwe, futhi imodeli enemininingwane "yendlela yesignali elahlekile" kufanele isungulwe, njengokuthi: ukuhlanganisa nge-substrate, izikhonkwane zephakheji, nezintambo zokubopha (Bondwire) phakathi kwe-substrate. ukuhlanganisa, nokuhlanganisa ngentambo kagesi.
Ukuphazamiseka kwesiteshi okuseduze ekufanisweni kwesekhethi yomsakazo
Ukuhlanekezela nakho kudlala indima ebalulekile kusidlulisi.I-non-linearity eyenziwe yi-transmitter kumjikelezo ophumayo ingase isakaze umkhawulokudonsa wesiginali edlulisiwe eziteshini eziseduze.Lesi simo sibizwa ngokuthi "ukukhula kabusha kwe-spectral".Ngaphambi kokuba isignali ifinyelele ku-amplifier yamandla we-transmitter (PA), umkhawulokudonsa wayo unomkhawulo;kodwa "ukuhlanekezela kwe-intermodulation" ku-PA kuzobangela ukuthi umkhawulokudonsa ukhuphuke futhi.Uma umkhawulokudonsa ukhuphuka kakhulu, umthumeli ngeke akwazi ukuhlangabezana nezidingo zamandla eziteshi zawo eziseduze.Lapho udlulisa amasignali alungiswe ngedijithali, empeleni, i-SPICE ayikwazi ukusetshenziselwa ukubikezela ukukhula okuqhubekayo kwe-spectrum.Ngoba ukudluliswa kwezimpawu ezingaba ngu-1,000 (uphawu) kufanele kufaniswe ukuze kutholwe i-spectrum emele, futhi amagagasi enkampani ethwala imvamisa ephezulu kufanele ahlanganiswe, okuzokwenza ukuhlaziya kwesikhashana kwe-SPICE kungenzeki.