Ngaphambi kokuqonda ubuchwepheshe be-PAM4, buyini ubuchwepheshe be-modulation? Ubuchwepheshe be-modulation buyindlela yokuguqula amasignali e-baseband (amasignali kagesi angahluziwe) abe amasignali okudlulisa. Ukuze uqinisekise ukusebenza kahle kokuxhumana futhi unqobe izinkinga ekudlulisweni kwesignali ekude, kuyadingeka ukudlulisa i-spectrum yesignali esiteshini esiphezulu se-frequency ngokusebenzisa i-modulation yokudlulisa.
I-PAM4 iyindlela yesine yokushintshashintsha kwe-pulse amplitude (PAM) ye-oda lesine.
Isignali ye-PAM iwubuchwepheshe obudumile bokudlulisa isignali ngemva kwe-NRZ (Non Return to Zero).
Isignali ye-NRZ isebenzisa amaleveli esignali amabili, aphezulu naphansi, ukuze imele u-1 no-0 wesiginali ye-digital logic, futhi ingadlulisela ibhithi elingu-1 lolwazi olunengqondo ngomjikelezo wewashi ngalinye.
Isignali ye-PAM4 isebenzisa amaleveli esignali angu-4 ahlukene ukuze idlulise isignali, futhi umjikelezo wewashi ngamunye ungadlulisela amabhithi angu-2 olwazi olunengqondo, okungukuthi 00, 01, 10, kanye no-11.
Ngakho-ke, ngaphansi kwezimo ezifanayo zesilinganiso se-baud, izinga elincane lesignali ye-PAM4 liphindwe kabili kunesiginali ye-NRZ, ephinda kabili ukusebenza kahle kokudlulisela futhi inciphise ngempumelelo izindleko.
Ubuchwepheshe be-PAM4 busetshenziswe kabanzi emkhakheni wokuxhumanisa isignali ngesivinini esikhulu. Njengamanje, kukhona i-module ye-400G ye-transceiver optical esekelwe kubuchwepheshe be-PAM4 bemodulation yesikhungo sedatha kanye ne-50G optical transceiver module esekelwe kubuchwepheshe be-PAM4 bokumodulisa kunethiwekhi ye-5G yokuxhuma.
Inqubo yokuqaliswa kwe-module ye-400G DML ye-transceiver optical transceiver esekelwe ku-PAM4 modulation ingokulandelayo: lapho udlulisela amasignali eyunithi, iziteshi ezitholiwe ze-16 ze-25G NRZ amasignali kagesi afakiwe kusuka kuyunithi yesixhumi esibonakalayo sikagesi, ecutshungulwe ngaphambili yiprosesa ye-DSP, i-PAM4 ishintshiwe, futhi ukuphuma kweziteshi eziyi-8 zezimpawu zikagesi ze-25G PAM4, ezilayishwa ku-chip yomshayeli. Izimpawu zikagesi ezihamba ngesivinini esikhulu ziguqulwa zibe iziteshi ze-8 ze-50Gbps izibonakaliso ze-optical zejubane eliphezulu ngokusebenzisa iziteshi ze-lasers ze-8, ezihlanganiswe ne-multiplexer ye-wavelength division, futhi ihlanganiswe ku-1 wesiteshi se-400G okukhipha isignali ye-high-speed optical. Lapho ithola amasignali eyunithi, isignali ye-1-channel 400G etholiwe ye-high-speed optical ifakwa ngeyunithi ye-optical interface, iguqulelwe ku-8-channel 50Gbps isignali ye-high-speed optical nge-demultiplexer, etholwe yisamukeli se-optical, futhi iguqulelwe kugesi kagesi. isignali. Ngemuva kokubuyiswa kwewashi, ukukhulisa, ukulinganisa, kanye nokwehliswa kwe-PAM4 nge-chip yokucubungula i-DSP, isignali kagesi iguqulwa ibe iziteshi ezingu-16 zesignali kagesi ye-25G NRZ.
Sebenzisa ubuchwepheshe bokumodulation be-PAM4 kumamojula we-400Gb/s optical. I-400Gb/s imojula ye-optical esekelwe ku-PAM4 modulation inganciphisa inani lama-lasers adingekayo ekugcineni kokudlulisa futhi ngokuhambisanayo inciphise inani labamukeli abadingekayo ekugcineni kokwamukela ngenxa yokusetshenziswa kwamasu okulinganisa aphezulu uma kuqhathaniswa ne-NRZ. Ukuguqulwa kwe-PAM4 kunciphisa inani lezingxenye ze-optical module optical, ezingaletha izinzuzo ezifana nezindleko eziphansi zomhlangano, ukunciphisa ukusetshenziswa kwamandla, nosayizi omncane wokupakisha.
Kunesidingo samamojula we-50Gbit / s optical kumanethiwekhi wokudlulisa we-5G kanye ne-backhaul, futhi isisombululo esisekelwe kumadivayisi we-25G optical futhi sengezwe yifomethi ye-PAM4 ye-pulse amplitude modulation iyamukelwa ukuze kuzuzwe izidingo zomkhawulokudonsa ophansi futhi ophezulu.
Uma uchaza amasiginali we-PAM-4, kubalulekile ukunaka umehluko phakathi kwesilinganiso se-baud ne-bit rate. Kuzimpawu zendabuko ze-NRZ, njengoba uphawu olulodwa ludlulisela ingxenye eyodwa yedatha, isilinganiso sebhithi kanye nezinga le-baud kuyefana. Isibonelo, ku-100G Ethernet, usebenzisa izimpawu ezine ze-25.78125GBaud zokudlulisa, izinga elincane kusignali ngayinye liphinde libe yi-25.78125Gbps, futhi amasignali amane afinyelela ukudluliswa kwesignali ye-100Gbps; Kumasiginali we-PAM-4, njengoba uphawu olulodwa ludlulisela amabhithi edatha angu-2, izinga lebhithi elingadluliswa liphindwe kabili izinga le-baud. Isibonelo, usebenzisa iziteshi ze-4 zezimpawu ze-26.5625GBaud zokudlulisela ku-200G Ethernet, isilinganiso esincane esiteshini ngasinye singama-53.125Gbps, futhi iziteshi ze-4 zamasignali zingafinyelela ukudluliswa kwesignali ye-200Gbps. Ku-400G Ethernet, ingafinyelelwa ngeziteshi ze-8 zezimpawu ze-26.5625GBaud.
Isikhathi sokuthumela: Jan-02-2025