No ke aha e hoʻohana ai nā Pūnaewele Pūnaewele i ka 25MHz a me kāna mau lehulehu e like me nā alapine?

No ke aha e hoʻohana ai nā Pūnaewele Pūnaewele i ka 25MHz a me kāna mau lehulehu e like me nā alapine?

Ma nā ʻenehana pūnaewele e like me nā kāleka pūnaewele, nā hoʻololi, nā mea alalai, a me nā lako Ethernet, ʻo ke koho ʻana i ka frequency oscillator crystal e hoʻoholo ʻia e nā hana koʻikoʻi o ka hāmeʻa, nā koi chip, a me nā kūlana protocol kamaʻilio. ʻO ka hoʻohana ʻana i nā oscillators crystal me ka alapine o 25MHz a me kāna mau mea nui ma muli o ka pili kokoke ʻana o kēia ʻōnaehana alapine me nā maʻamau Ethernet, nā protocols kamaʻilio, a me nā hale hana chip, e hiki ai i ka hoʻolālā maʻalahi, hoʻemi ʻia nā kumukūʻai, a me ka hoʻomaikaʻi ʻana i ka hana. Aia ka wehewehe kikoʻī ma lalo nei:

I. No ke aha e koho ai i ka 25MHz e like me ka Base Frequency?

ʻAʻole ʻo 25MHz kahi waiwai i koho ʻia. Hoʻohana nui ʻia ʻo ia no ka mea he pilina helu integer me kekahi mau alapine koʻikoʻi i ke kamaʻilio pūnaewele, hoʻomaʻamaʻa i ka hoʻonui pinepine ʻana a i ʻole ka mahele.

1.1 Hoʻokō i nā koi ʻo Ethernet Standard Frequency

ʻO Ethernet wikiwiki (100BASE-TX): Hoʻohana i ka uaki 25MHz e like me ke alapine o ka lawe ʻana i ka ʻikepili.

Gigabit Ethernet (1000BASE-T): Hoʻohana i ka uaki 125MHz, ʻo ia ka 25MHz × 5.

10GbE (10 Gigabit Ethernet) a ʻoi aku: ʻOiai ʻoi aku ka kiʻekiʻe o ke alapine o ka uaki nui (e laʻa, 156.25MHz), hiki ke loaʻa ma ka hoʻonui ʻana i ka oscillator kristal 25MHz ma o PLL.

Hōʻike kēia i ka 25MHz, e like me ke alapine o ka uaki kumu, hiki ke kākoʻo pololei a i ʻole ke kākoʻo ʻole i nā alapine hana o PHY/MAC no nā wikiwiki Ethernet mainstream.

II. Maikaʻi hoʻokō ʻenehana

2.1 Hoʻonui pinepine ʻia ma o PLL

Hoʻohana pinepine ʻia nā ʻāpana pūnaewele (e like me PHY, MAC, a me nā ʻāpana hoʻololi) i nā kaapuni PLL (Phase Locked Loop) i loko no ka hoʻopuka ʻana i nā alapine uaki pono e pono ai . 25MHz he alapine komo haʻahaʻa e hiki ai ke hoʻohua i nā alapine kiʻekiʻe maʻamau -wikiwiki, e like me:

25MHz × 2=50MHz

25MHz × 4=100MHz

25MHz × 5=125MHz

25MHz × 6.25=156.25MHz (no 10GbE)

No ka mea, ʻo 25MHz kahi alapine kumu me ka maʻalahi-e-heluhelu i nā helu helu haʻahaʻa, ua maʻalahi ia i ka hoʻolālā PLL, hiki i ka laka wikiwiki ʻana, a e hōʻoia i ka hoʻopuka paʻa.

2.2 Kūlike me nā Koina Chip Mainstream

Kākoʻo nui ka hapa nui o nā mea hana kīpē pūnaewele (e like me Broadcom, Realtek, Marvell, Intel, etc.) i ka 25MHz crystal oscillator hoʻokomo i nā koi o ka uaki hoʻokomo o kā lākou PHY a i ʻole MAC chips, a i ʻole hāʻawi i nā ʻano hana no ka hoʻokomo 25MHz.

III. ʻO nā pōmaikaʻi ma EMC, Circuit Design, a me ke kumukūʻai

3.1 ʻOi aku ka maikaʻi o ka mana EMI a me ka hōʻailona kiʻekiʻe

Hoʻohālikelike ʻia me nā oscillators crystal me nā alapine kiʻekiʻe (e laʻa, 50MHz, 100MHz, 125MHz, 150MHz, a me 200MHz), hāʻawi ʻo 25MHz i nā pono nui i ka ʻōlelo o ka Electromagnetic Interference (EMI):

ʻO ka haʻahaʻa haʻahaʻa kumu ka hopena i ka liʻiliʻi o ka harmonic interferences;

ʻOi aku ka maʻalahi o ka hoʻokele PCB e hoʻokō me nā kikoʻī hoʻolālā EMI;

Nā koi haʻahaʻa no nā paʻa a me ka pono o ka mana, e hoʻomaʻamaʻa i ka hoʻohui ʻana o ka ʻōnaehana.

3.2 Nā Oscillator Crystal ʻOʻo, Paʻa, a me ke Kumukuai

ʻO 25MHz crystal oscillators i waena o nā alapine i hoʻohana nui ʻia i ka ʻoihana uila, me nā pono aʻe:

He nui loa i-ka-huahana a me na ano like ole;

ʻO nā kumukūʻai hana haʻahaʻa a me nā kumukūʻai kūʻai kūpono;

He kaulahao hoʻolako makua me nā manawa alakaʻi pōkole a me ka maikaʻi paʻa.

He mea maikaʻi kēia i nā mea hana ʻenehana pūnaewele e hana ana i ka hana nui-.

IV. Laʻana Hoʻohana ma ka Hoʻolālā Practical

Ke lawe nei i kahi hoʻololi Gigabit Ethernet ma ke ʻano he laʻana:

Pono ka puʻupuʻu mana nui i kahi alapine hana hoʻokomo o 125MHz;

Ma ka hoʻolālā, hiki ke hoʻohana ʻia kahi oscillator kristal 25MHz, a hiki ke hoʻonui ʻia ke alapine i 125MHz ma o ka chip i kūkulu ʻia-ma PLL;

I kēia manawa, hiki ke hoʻokaʻawale ʻia ka uaki 25MHz i nā modula ʻē aʻe (e like me PHY, MAC, a i ʻole nā ​​modules synchronization clock) ma o kahi lāʻau uaki;

Loaʻa kēia i kahi kumu uaki hui, hoʻomaʻamaʻa i ka hoʻolālā uaki, a hoʻemi i ka paʻakikī o ka ʻōnaehana a me nā kumukūʻai.

Hōʻuluʻulu manaʻo

Hiki ke hōʻuluʻulu ʻia nā kumu e hoʻohana ai nā ʻenehana pūnaewele i ka 25MHz a me kāna mau helu like me nā alapine oscillator kristal.

Hoʻohana nui ʻia ʻo Hangjing Crystal Oscillators i nā polokalamu pūnaewele (nā kāleka pūnaewele, nā hoʻololi, nā mea ala, Ethernet). Ma waho aʻe o nā huahana -ʻoihana, hāʻawi pū mākou i ka laulā-mahana kiʻekiʻe{3}}stability crystal oscillators (-55~+125 degere ) a hiki ke hāʻawi i ka hoʻohana ʻana i ka oscillator crystal a me nā hāʻina like. Inā loaʻa iā ʻoe nā pono kūpono, e ʻoluʻolu e hoʻokaʻaʻike aku i nā mea kūʻai aku a Hangjing paha.