Wannan labarin yana bayyana mahimman halaye 4 na da'irori RF daga bangarori huɗu: RF dubawa, ƙaramin siginar da ake tsammani, babban siginar tsangwama, da tsangwama daga tashoshi masu kusa, kuma yana ba da mahimman abubuwan da ke buƙatar kulawa ta musamman a cikin tsarin ƙirar PCB.
RF kewaye kwaikwaiyo na ke dubawa na RF
Mai watsawa mara waya da mai karɓa a cikin ra'ayi, ana iya raba shi zuwa sassa biyu na mahimman mitar rediyo da mitar rediyo.Mahimmin mitar ya ƙunshi mitar siginar shigar da mai aikawa da mitar siginar fitarwa na mai karɓa.bandwidth na mitar mahimmanci yana ƙayyade ƙimar asali wanda bayanai zasu iya gudana a cikin tsarin.Ana amfani da mitar mahimmanci don inganta amincin bayanan da ke gudana da kuma rage nauyin da mai watsawa ya sanya a kan hanyar watsawa a wani adadin bayanai.Don haka, ƙirar PCB na mahimmancin da'irar mitar tana buƙatar ɗimbin ilimin injiniyan sarrafa sigina.Da'irar RF na mai watsawa tana jujjuya da haɓaka siginar siginar da aka sarrafa zuwa takamaiman tashoshi kuma yana shigar da wannan siginar cikin matsakaicin watsawa.Akasin haka, da'irar RF mai karɓar mai karɓa yana samun sigina daga kafofin watsa labarai kuma yana jujjuya shi da saukar da shi zuwa ainihin mitar.
Masu watsawa suna da manyan manufofin ƙira na PCB guda biyu: na farko shine dole ne su watsa takamaiman adadin wuta yayin da suke cinye mafi ƙarancin ƙarfin da zai yiwu.Na biyu shi ne cewa ba za su iya tsoma baki tare da al'ada aiki na transceiver a kusa da tashoshi.Dangane da mai karɓa, akwai manyan manufofin ƙira na PCB guda uku: na farko, dole ne su dawo daidai da ƙananan sigina;na biyu, dole ne su iya cire alamun tsangwama a waje da tashar da ake so;batu na ƙarshe daidai yake da mai watsawa, dole ne su cinye ƙarfi kaɗan.
Simintin kewayawa na RF na manyan sigina masu shiga tsakani
Dole ne masu karɓa su kasance masu kula da ƙananan sigina, koda lokacin da manyan sigina masu shiga tsakani (blockers) suke.Wannan yanayin yana tasowa lokacin ƙoƙarin karɓar sigina mai rauni ko mai nisa tare da watsa shirye-shiryen watsawa mai ƙarfi a tashar da ke kusa.Siginar shiga tsakani na iya zama 60 zuwa 70 dB mafi girma fiye da siginar da ake tsammani kuma zai iya toshe karɓar sigina na al'ada a cikin lokacin shigar da mai karɓa tare da babban adadin ɗaukar hoto ko kuma ta haifar da mai karɓa ya haifar da yawan adadin amo a cikin lokacin shigarwa.Wadancan matsalolin guda biyu da aka ambata a sama suna iya faruwa idan mai karɓa, a cikin matakin shigarwa, an tura shi zuwa cikin yankin rashin daidaituwa ta hanyar tsoma baki.Don guje wa waɗannan matsalolin, ƙarshen gaba na mai karɓar dole ne ya zama madaidaiciya.
Saboda haka, "linearity" yana da mahimmancin la'akari lokacin zayyana PCB mai karɓa.Kamar yadda mai karɓa ya kasance da'irar kunkuntar-band, don haka rashin daidaituwa shine auna "hargitsi na tsaka-tsakin tsaka-tsakin" zuwa ƙididdiga.Wannan ya ƙunshi amfani da igiyoyin sine ko cosine guda biyu masu kama da juna kuma suna cikin rukunin tsakiya (a cikin band) don fitar da siginar shigarwa, sannan auna samfurin juzu'in ta.Gabaɗaya, SPICE software ce mai ɗaukar lokaci kuma mai tsada saboda dole ne ta yi zagayawa da yawa kafin ta sami ƙudurin mitar da ake so don fahimtar murdiya.
RF kewaye simintin ƙaramar siginar da ake so
Dole ne mai karɓa ya kasance mai kulawa sosai don gano ƙananan siginar shigarwa.Gabaɗaya, ikon shigar da mai karɓa zai iya zama ƙarami kamar 1 μV.Hankalin mai karɓar yana iyakance ne ta hanyar hayaniyar da ke haifar da da'irar shigar da shi.Saboda haka, amo yana da mahimmancin la'akari lokacin zayyana mai karɓa don PCB.Bugu da ƙari, samun ikon tsinkayar amo tare da kayan aikin kwaikwayo yana da mahimmanci.Hoto 1 shine mai karɓar superheterodyne (superheterodyne).Ana fara tace siginar da aka karɓa sannan kuma ana ƙara siginar shigar da ƙaramar ƙaramar ƙararrawa (LNA).Ana amfani da oscillator na farko na gida (LO) don haɗawa da wannan siginar don canza wannan siginar zuwa mitar matsakaici (IF).Ƙarshen gaba (ƙarshen gaba) ingancin hayaniyar kewayawa ya dogara musamman akan LNA, mahaɗa (mixer) da LO.ko da yake yin amfani da na al'ada SPICE amo analysis, za ka iya neman LNA amo, amma ga mahautsini da LO, ba shi da amfani, domin amo a cikin wadannan tubalan, zai zama wani babban LO sigina da tsanani shafa.
Ƙaramar siginar shigarwa tana buƙatar mai karɓa ya kasance mai girma sosai, yawanci yana buƙatar riba kamar 120 dB.A irin wannan babban riba, duk siginar da aka haɗa daga fitarwa (ma'aurata) baya zuwa shigarwar na iya haifar da matsala.Muhimmin dalili na yin amfani da tsarin gine-ginen mai karɓa na super outlier shine don yana ba da damar rarraba ribar akan mitoci da yawa don rage damar haɗin gwiwa.Wannan kuma ya sa mitar LO ta farko ta bambanta da mitar siginar shigarwa, zai iya hana babban siginar tsangwama "ƙazanta" zuwa ƙaramin siginar shigarwa.
Don dalilai daban-daban, a wasu tsarin sadarwa mara waya, jujjuya kai tsaye (canzawa kai tsaye) ko gine-gine daban-daban (homodyne) na iya maye gurbin gine-ginen banbanta na waje.A cikin wannan gine-gine, siginar shigarwar RF yana canzawa kai tsaye zuwa mitar mahimmanci a cikin mataki ɗaya, ta yadda yawancin ribar yana cikin mitar mahimmanci kuma LO yana daidai da siginar shigarwa.A wannan yanayin, dole ne a fahimci tasirin ƙananan haɗin gwiwa kuma dole ne a kafa cikakken samfurin "hanyar siginar siginar" kamar: haɗawa ta hanyar substrate, haɗawa tsakanin sawun kunshin da layin solder (bondwire) , da kuma haɗawa ta hanyar haɗin layin wutar lantarki.
Kwaikwaiyon Da'irar RF na Tsangwama Tashar Maƙwabta
Har ila yau, murdiya tana taka muhimmiyar rawa wajen watsawa.Rashin daidaituwar da mai watsawa ke haifarwa a cikin da'irar fitarwa na iya haifar da faɗin mitar siginar da aka watsa a cikin tashoshi masu kusa.Wannan al'amari shi ake kira "spectral regrowth".Kafin siginar ta kai ga ma'aunin ƙarfin mai watsawa (PA), bandwidth ɗin sa yana da iyaka;duk da haka, "hargitsi na tsaka-tsakin" a cikin PA yana sa bandwidth ya sake karuwa.Idan bandwidth ya karu da yawa, mai watsawa ba zai iya biyan bukatun wutar lantarki na tashoshin makwabta ba.Lokacin aikawa da siginar daidaitawa na dijital, ba zai yuwu a zahiri a iya hasashen sake girmar bakan tare da SPICE ba.Domin kusan alamomin dijital 1000 (alama) na aikin watsawa dole ne a kwaikwayi su don samun bakan wakilci, kuma suna buƙatar haɗa babban mai ɗaukar hoto, waɗannan za su sa binciken ɗan lokaci na SPICE ya zama mara amfani.
Lokacin aikawa: Maris-31-2022