Ngenxa yosayizi omncane nosayizi, cishe awekho amazinga e-Contireity Board akhona eMakethe ye-IOT ekhulayo ekhulayo. Ngaphambi kokuthi kuphume la mazinga, kwadingeka sithembele olwazini nasezihlangenwe nakho okufundwayo okufundwe ekuthuthukisweni kwezinga leBhodi futhi bacabange ukuthi bangazisebenzisa kanjani ezinseleleni ezivelayo ezihlukile. Kunezindawo ezintathu ezidinga ukunakwa kwethu okukhethekile. Yilezi: izinto ze-circuit board ezingaphezulu, i-RF / microwave design kanye nemigqa yokuhambisa i-RF.

I-PCB Material

"I-PCB" ngokuvamile iqukethe ama-laminate, angenziwa nge-epoxy eqiniswe nge-fiber-field (FR4), i-polymide noma izinto ze-roger noma ezinye izinto ze-liquate. Izinto ezifakiwe eziphakathi kwezingqimba ezahlukahlukene zibizwa ngokuthi yi-prepreg.

Amadivaysi agqokayo adinga ukuthembeka okuphezulu, ngakho-ke lapho abaklami be-PCB bebhekene nokukhethwa kokusebenzisa i-FR4 (impahla ebiza kakhulu ye-PCB esebenza kakhulu) noma izinto ezithuthukile ezithuthukile, lokhu kuzoba yinkinga.

Uma izinhlelo zokusebenza ze-PCB ezigqokekayo zidinga isivinini esiphakeme, izinto ezivame kakhulu, i-FR4 kungenzeka zingabi yisinqumo esihle kunazo zonke. I-dielectric ihlala njalo (DK) ka-FR4 ngu-4,5, i-dielectric ihlala i-rogers 4003 series ezibonakalayo ngu-3.55, futhi i-dielectric of the gener chungechunge

“The dielectric constant of a laminate refers to the ratio of the capacitance or energy between a pair of conductors near the laminate to the capacitance or energy between the pair of conductors in vacuum. At high frequencies, it is best to have a small loss. Therefore, Roger 4350 with a dielectric constant of 3.66 is more suitable for higher frequency applications than FR4 with a dielectric constant of 4.5.

Ngaphansi kwezimo ezijwayelekile, inani lezendlalelo se-PCB samadivayisi agqokekayo asukela ezingxenyeni ezi-4 kuye kwayi-8. Umgomo wokwakhiwa kwesendlalelo ukuthi uma kuyi-PCB enobungqingili, kufanele ikwazi ukuhlinzeka ngokwanele phansi nezingqimba zamandla kanye nesamentshisi ingqimba ye-wiring. Ngale ndlela, umphumela we-ripple eCrosstalk ungagcinwa kubuncane futhi obuphazanyiswa nge-electromagnete (EMI) kungancishiswa kakhulu.

Esigabeni sokuklanywa kwebhodi lesekethe, uhlelo lokuhlelwa luvame ukubeka ungqimba olukhulu lomhlabathi eduze kwesendlalelo sokusabalalisa amandla. Lokhu kungadala umphumela ophansi kakhulu we-ripple, futhi umsindo wesistimu ungancishiswa ukuze ucishe abe ngu-zero. Lokhu kubaluleke kakhulu kwimvamisa yomsakazo.

Uma kuqhathaniswa ne-roger material, i-FR4 ine-factor ephakeme ye-dissipation (DF), ikakhulukazi imvamisa ephezulu. Ukusebenza okuphezulu u-Fr4 Laminates, inani le-DF licishe libe ngu-0.002, okuwumyalelo wobukhulu obungcono kuno-fr4 ojwayelekile. Kodwa-ke, isitaki sikaRogers 'singu-0,001 noma ngaphansi. Lapho kusetshenziswa izinto ezi-Fr4 ze-High Frequency application, kuzoba nomehluko omkhulu ekulahlekelweni kokufaka. Ukulahleka kokufaka kuchazwa njengokulahleka kwamandla kwesiginali kusuka kuPhoyinti A kuya ku-Photo B lapho usebenzisa i-FR4, Roger noma ezinye izinto.

Dala izinkinga

I-PCB egqoke idinga ukulawulwa okuqinile kokulawulwa. Lesi yinto ebalulekile yamadivayisi agqokekayo. Ukuqhathanisa kokungcola kungakhiqiza ukuhanjiswa kwesiginali okuhlanzayo. Phambilini, ukubekezelela okujwayelekile kweminambitha yokuphatha kwakungu- ± 10%. Le nkomba ngokusobala ayilungile ngokwanele ukuba ngcono kakhulu kwanamuhla kanye namasekethe asheshe. Isidingo samanje singu- ± 7%, futhi kwezinye izimo ngisho ± 5% noma ngaphansi. Le phapha kanye nokunye okuguquguqukayo kuzothinta kakhulu ukwenziwa kwalawa ma-PC e-FCB aqinile ngokulawulwa okuqinile, ngaleyo ndlela kunciphise inani lamabhizinisi angenza.

Ukubekezelela okuqhubekayo kwe-dielectic kwe-laminate eyenziwe ngama-roger UHF wezinto zokwenziwa ngokuvamile kugcinwa ku- ± 2%, kanti eminye imikhiqizo ingafinyelela ngisho ± 1%. Ngokuphambene nalokho, ukubekezelela okuqhubekayo kwe-fr4 laminate kuphakama njenge-10%. Ngakho-ke, qhathanisa lezi zinto ezimbili ezingatholakala ukuthi ukulahleka kokufaka kukaRoger 'kuphansi kakhulu kuphansi kakhulu. Uma kuqhathaniswa nezinto zokwenziwa zendabuko fr4, ukulahleka kokuhambisa nokulahleka kokufaka kwe-rogers stack kuphansi okuphansi.

Ezimweni eziningi, izindleko zibaluleke kakhulu. Kodwa-ke, ama-roger anganikeza ngokulahleka okuphansi kokusebenza okuphezulu okuphezulu kwe-liquency at enendawo yentengo eyamukelekayo. Okokusebenza kwezentengiso, ama-roger angenziwa abe yi-PCB ye-hybrid ene-epoxy-based fr4, ezinye izingqimba zazo ezisebenzisa izinto ze-rogers, nezinye izingqimba zisebenzisa u-FR4.

Lapho ukhetha isitaki se-roger, imvamisa ukucatshangelwa okuyinhloko. Lapho imvamisa idlula ama-500mhz, abaklami be-PCB bavame ukukhetha izinto ze-rogers, ikakhulukazi amaseliphu e-RF / microwave, ngoba lezi zinto zokwakha zinganikeza ukusebenza okuphezulu lapho kulawulwa ngokuqinile ngenxa yokuvinjwa.

Uma kuqhathaniswa nezinto ezi-FR4, izinto ezi-roger nazo zinganikela ngokulahleka okuphansi kwe-dielectric, futhi i-dielectric yayo njalo iqinile ebangeni elijwayelekile. Ngaphezu kwalokho, izinto ezibonakalayo ze-roger zinganikeza ukusebenza okuhle kokufakwa okuphansi okudingekayo ngokusebenza imvamisa ephezulu.

I-coefficie ekwandisweni kwe-thermal (CTE) kaRoger 4000 Izinsiza zokwelashwa zinokuqina okuhle kakhulu. Lokhu kusho ukuthi uma kuqhathaniswa no-FR4, lapho i-PCB ithola imijikelezo ebabandayo futhi eshisayo futhi eshisa kakhulu yokubonisa, ukukhishwa kwebhodi lokujikeleza kwe-Thermal kungagcinwa emkhawulweni oqinile ngaphansi kwemvamisa ephezulu nemijikelezo ephakeme yokushisa.

Endabeni yokufaka okuxubile, kulula ukusebenzisa ubuchwepheshe bezinqubo zokukhiqiza ezijwayelekile ukuxuba ama-roger kanye nokusebenza okuphezulu kwe-fr4 ndawonye, ​​ngakho-ke kulula ukufeza isivuno esiphezulu sokukhiqiza. Isitaki se-roger asidingi inqubo ekhethekile yokulungiselela.

I-Fr4 ejwayelekile ayikwazi ukufezekisa ukusebenza kukagesi okuthembekile, kepha izinto ezisebenza kahle ze-FR4 zinezici ezinhle zokwethenjwa, njenge-TG ephakeme, zisezindleko eziphansi, futhi zingasetshenziswa ezinhlelweni ezibanzi zomsindo ezihlelweni eziyinkimbinkimbi ze-microwave.

Ukucatshangelwa Kwedizayini ye-RF / Microwave

Ubuchwepheshe obuphathekayo kanye ne-Bluetooth kuveze indlela yezinhlelo zokusebenza ze-RF / microwave kumadivayisi agqokekayo. Ibanga lemvamisa lanamuhla liya ngokuya linamandla. Eminyakeni embalwa edlule, imvamisa ephezulu kakhulu (i-VHF) yachazwa njenge-2GHz ~ 3GHz. Kepha manje sesikwazi ukubona izinhlelo ze-Ultra-high frequency (UHF) ezisukela ku-10ghz ziye ku-25GHz.

Ngakho-ke, nge-PCB egqokekayo, ingxenye ye-RF idinga ukunakwa okwengeziwe ezindabeni ze-wiring, futhi amasiginali kufanele ahlukaniswe ngokwahlukana, futhi iminonjana ekhiqiza amasignali afinyelela ku-high-frequency kufanele igcinwe kude nomhlabathi. Okunye ukucatshangelwa kufaka phakathi: Ukuhlinzeka ngesihlungi se-bypass, ama-capacitors awenele okukhohlisa, ukufuya, kanye nokuklama umugqa wokudlulisela kanye nomugqa wokubuyisela acishe alingana.

Isihlungi se-Bypass singacindezela umphumela we-ripple wokuqukethwe komsindo ne-crosstalk. Ama-capacitors aqothulayo adinga ukubekwa eduze kwezikhonkwane zedivayisi eziphethe amasiginali wamandla.

Imigqa yokudluliselwa ngejubane eliphezulu kanye namasekethe wesiginali adinga ukubekwa ungqimba lomhlabathi phakathi kwamasiginali we-Power ungqimba ukuze abushelelezi i-jitter eyenziwe yizimpawu zomsindo. Ngejubane eliphakeme lesiginali, ama-mismatches amancane okulimaza azodala ukudluliselwa okungalinganiseli nokwamukelwa kwezimpawu, okuholela ekuhlanekezelweni. Ngakho-ke, ukunakwa okukhethekile kufanele kukhokhwe kwinkinga yokufanisa i-Impodance ehlobene nesibonakaliso semvamisa yomsakazo, ngoba isibonakaliso se-Radio Frequency sinesivinini esikhulu nokubekezelela okukhethekile.

Imigqa yokudluliswa ye-RF idinga ukukhishwa okulawulwayo ukuze kudluliselwe amasiginali we-RF kusuka ku-IC substrate ethile kwi-PCB. Le migqa yokuhambisa ingaqaliswa engxenyeni yangaphandle, ungqimba oluphezulu, nesendlalelo esingezansi, noma senzelwe ungqimba oluphakathi.

Izindlela ezisetshenziswe ngesikhathi se-PCB RF Design Layout yilayini ye-MicroSTRIP, umugqa we-strip ontantayo, i-coplanar waveguide noma isisekelo. Umugqa we-MicroSTrip uqukethe ubude obuhleliwe bensimbi noma umkhondo kanye nendiza yonke yomhlaba noma ingxenye yendiza yomhlabathi ngqo ngaphansi kwayo. Ukuvinjwa kwesimo ku-General MicroSTRIP Line Hlela kusuka ku-50ω kuya ku-75ω.

I-stripline entantayo ingenye indlela yokunyanyelelwa kwe-wiring kanye nomsindo. Lomugqa uqukethe i-wiring ebanzi ehleliwe engxenyeni engaphakathi kanye nendiza enkulu yomhlaba ngenhla nangaphansi komqhubi wesikhungo. Indiza yomhlabathi ihlanganiswa phakathi kwendiza yamandla, ngakho-ke inganikeza umphumela osebenza kahle kakhulu. Le yindlela ekhethwayo ye-wiring yesiginali ye-PCB RF egqokekayo.

I-Coplanar WaveGuide inganikeza ukwahlukaniswa okungcono eduze komjikelezo we-RF kanye nomjikelezo odinga ukusondeza eduze. Le ndlela iqukethe umqhubi we-conductor omaphakathi kanye nezindiza zomhlaba ngapha nangapha. Indlela engcono kakhulu yokudlulisa amasiginali we-Radio Frequency ukumisa imigqa ye-strip noma ama-coplanar wavegcuides. Lezi zindlela ezimbili zinganikeza ukwahlukaniswa okungcono phakathi kokulandela iziginali kanye ne-RF.

Kunconywa ukusebenzisa okubizwa ngokuthi "ngocingo" ezinhlangothini zombili ze-coplanar waveguide. Le ndlela inganikeza umugqa we-vias ye-Ground kwindiza ngayinye yensimbi yomqhubi wesikhungo. I-Trace eyinhloko egijima maphakathi inocingo ohlangothini ngalunye, ngaleyo ndlela inikeze isinqamuleli sokubuya kwamanje emhlabathini ongezansi. Le ndlela inganciphisa izinga lomsindo elihlotshaniswa nomphumela ophezulu we-ripple wesiginali ye-RF. I-dielectric ihlala i-4.5 ihlala ifana nokuqukethwe kwe-FR4 kwe-prepreg, kuyilapho i-dielectric ihlala njalo i-microsTrip, i-stripline noma i-striplines ecishe ibe ngu-3.8 kuya ku-3.9.

Kwamanye amadivaysi asebenzisa indiza emhlabathini, kungenzeka ukuthi i-vias vias ingahle isetshenziselwe ukuthuthukisa ukusebenza okukhohlisayo kwe-capacitor yamandla futhi inikeze indlela ye-shunt evela emhlabathini. Indlela ye-shunt iya emhlabathini inganciphise ubude be-via. Lokhu kungafinyelela izinhloso ezimbili: awugcini nje ngokudala i-shunt noma umhlabathi, kepha futhi unciphise ibanga lokuhambisa amadivaysi anezindawo ezincane, okuyisici esibalulekile se-RF Design.