Dɛn Nti na Network Devices De 25MHz ne Ne Multiples Di Dwuma Sɛ Frequencies?

Dɛn Nti na Network Devices De 25MHz ne Ne Multiples Di Dwuma Sɛ Frequencies?

Wɔ ntwamutam mfiri te sɛ ntwamutam kaad, switch, router, ne Ethernet mfiri mu no, wɔde afiri no dwumadi titiriw, chip ahwehwɛde, ne nkitahodi protocol gyinapɛn ahorow na ɛkyerɛ sɛnea wɔpaw crystal oscillator frequency. Crystal oscillators a ɛwɔ frequency 25MHz ne ne multiples a wɔde di dwuma no fi frequency system yi a ɛne Ethernet gyinapɛn, nkitahodi protocol, ne chip architectures hyia yiye, a ɛma wotumi yɛ nhyehyɛe a ɛyɛ mmerɛw, ɛka so tew, na ɛma adwumayɛ tu mpɔn. Wɔde nkyerɛkyerɛmu a ɛkɔ akyiri ama wɔ ase ha:

I. Dɛn nti na Paw 25MHz sɛ Base Frequency?

25MHz nyɛ botae a wɔpaw no ara kwa. Wɔde di dwuma kɛse efisɛ ɛwɔ integer multiple abusuabɔ a ɛne core frequencies pii wɔ network nkitahodi mu, na ɛma frequency multiplication anaa division yɛ mmerɛw.

1.1 Ɛdi Ethernet Standard Frequency Ahwehwɛdeɛ ho dwuma

Fast Ethernet (100BASE-TX): Ɛde 25MHz dɔn di dwuma sɛ data a wɔde mena mpɛn dodow.

Gigabit Ethernet (1000BASE-T): Ɛde 125MHz dɔn di dwuma, a ɛyɛ 25MHz × 5.

10GbE (10 Gigabit Ethernet) ne nea ɛboro saa: Ɛwom sɛ dɔn titiriw no frequency korɔn (sɛ nhwɛso no, 156.25MHz), mpɛn pii no wobetumi anya denam 25MHz crystal oscillator no a wɔbɛbɔ denam PLL so.

Wei kyerɛ sɛ 25MHz, sɛ base clock frequency no, betumi aboa PHY/MAC adwumayɛ frequency ahorow no tẽẽ anaasɛ ɛnte saa ama Ethernet ahoɔhare titiriw.

II. Mfiridwuma mu Nneɛma a Wɔde Di Dwuma a Ɛyɛ Mmerewa

2.1 Frequency Multiplication a ɛnyɛ den denam PLL so

Network chips (te sɛ PHY, MAC, ne switch chips) taa de PLL (Phase Locked Loop) circuits di dwuma wɔ wɔn mu de yɛ adwumayɛ dɔn frequency a wɔhwehwɛ. 25MHz yɛ input frequency a ɛkɔ fam a ebetumi ama frequency a ɛtaa yɛ high-speed frequencies ayɛ yiye, te sɛ:

25MHz × 2=50MHz na ɛwɔ hɔ

25MHz × 4=100MHz na ɛwɔ hɔ

25MHz × 5=125MHz na ɛwɔ hɔ

25MHz × 6.25=156.25MHz (ma 10GbE) .

Esiane sɛ 25MHz yɛ base frequency a ɛnyɛ den-sɛ-bu akontaa integer multiples a ɛba fam nti, ɛma PLL nhyehyɛe yɛ mmerɛw, ɛma wotumi tow ntɛmntɛm, na ɛhwɛ hu sɛ output a ɛyɛ pintinn kɛse.

2.2 Ɛne Mainstream Chip Ahwehwɛdeɛ hyia

Ntwamutam mfiri chip ayɛfo dodow no ara (te sɛ Broadcom, Realtek, Marvell, Intel, ne nea ɛkeka ho) boa 25MHz crystal oscillator input pefee wɔ input clock ahwehwɛde ahorow a ɛwɔ wɔn PHY anaa MAC chips mu, anaasɛ wɔde adwumayɛ akwan ma 25MHz input.

III. Mfaso a ɛwɔ EMC, Circuit Design, ne ɛka a wɔbɔ mu

3.1 EMI Control a eye ne Nsɛnkyerɛnneɛ a ɛkorɔn

Sɛ wɔde toto crystal oscillators a ɛwɔ frequency a ɛkorɔn (sɛ nhwɛso no, 50MHz, 100MHz, 125MHz, 150MHz, ne 200MHz) ho a, 25MHz ma mfaso kɛse wɔ Electromagnetic Interference (EMI) mu:

Fapem frequency a ɛba fam no ma harmonic interferences kakraa bi na ɛba;

PCB routing yɛ mmerɛw sɛ wobedi EMI design specifications so;

Ahwehwɛde a ɛba fam ma enclosures ne power integrity, a ɛma nhyehyɛe a wɔde bɛka abom no yɛ mmerɛw.

3.2 Crystal Oscillators a ɛho akokwaw, ɛyɛ den, na ɛho ka yɛ-Crystal Oscillators a Etu mpɔn

25MHz crystal oscillators ka frequency ahorow a wɔde di dwuma kɛse wɔ ɛlɛtrɔnik adwumayɛ mu no ho, na mfaso horow a edidi so yi wɔ so:

Abundant off-the-shelf nneɛma ne ahorow ahorow pii;

Nneɛma a wɔyɛ ho ka a ɛba fam ne nneɛma a wɔtɔ ho bo a ɛyɛ den;

Nneɛma a wɔde ma a ɛho akokwaw a ɛwɔ bere tiaa a wɔde di dwuma na ɛyɛ nea ɛyɛ den.

Eyi yɛ nea ɛyɛ anigye kɛse ma ntwamutam mfiri ayɛfo a wɔde wɔn ho hyɛ nneɛma akɛse-yɛ mu.

IV. Nhwɛso a Wɔde Di Dwuma wɔ Nsusuwii a Wɔde Di Dwuma Mu

Sɛ yɛfa Gigabit Ethernet switch sɛ nhwɛsoɔ a:

Control chip titiriw no hwehwɛ sɛ wɔde input adwumayɛ frequency a ɛyɛ 125MHz;

Wɔ nhyehyɛɛ no ​​mu no, wobetumi de 25MHz crystal oscillator adi dwuma, na wobetumi de frequency no abɔ 125MHz denam chip no a wɔasisi-wɔ PLL mu no so;

Saa berɛ yi, wɔbɛtumi akyekyɛ 25MHz dɔn no akɔ module foforɔ (te sɛ PHY, MAC, anaa dɔn synchronization module) denam dɔn dua so;

Eyi ma wonya dɔn fibea a ɛyɛ biako, ɛma dɔn nhyehyɛe no yɛ mmerɛw, na ɛtew nhyehyɛe no mu nsɛnnennen ne ɛka so.

Tɔfabɔ

Yebetumi abɔ nea enti a network mfiri ahorow de 25MHz ne ne multiples di dwuma sɛ crystal oscillator frequencies no mua sɛnea edidi so yi:

Wɔde Hangjing Crystal Oscillators di dwuma kɛse wɔ ntwamutam mfiri (network cards, switches, routers, Ethernet). Wɔ mfiridwuma-grade nneɛma akyi no, yɛsan nso de wide-temperature high-stability crystal oscillators (-55~+125℃) ma na yebetumi de crystal oscillator application ne matching solutions ama. Sɛ wowɔ ahiadeɛ a ɛfata a, yɛsrɛ wo, ntwentwɛn wo nan ase sɛ wobɛka Hangjing adetɔn anaa mfiridwuma ho adwumayɛfoɔ ho nkɔmmɔ.