I nā hihia he nui, PCB E hele ana nā uea i loko o nā lua, nā pads spot test, nā laina kumu pōkole, a pēlā aku. Pono e kālailai ʻia ka mana o ka capacitance ma ka hōʻailona mai ka hopena hoʻoili a me ka hopena e loaʻa ai, a he hopena ia ma ka wahi hoʻomaka a me ka hopena.

Kaomi mua e ʻike i ka hopena ma ka transmitter hōʻailona. Ke piʻi wikiwiki kahi hōʻailona piʻi i ka capacitor, hoʻopiʻi wikiwiki ka capacitor. Pili ka ʻāpana e hoʻouka nei i ka wikiwiki o ka piʻi ʻana o ka uila hōʻailona. ʻO ke kaomi hana i kēia manawa ʻo: I = C * dV / dt. ʻO ke kiʻekiʻe o ka capacitance, ʻo ke kiʻekiʻe o ke au e hoʻokau nei, ʻo ka wikiwiki o ka piʻi ʻana o ka hōʻailona, ​​ʻo ka dt liʻiliʻi, ʻoi aku ka kiʻekiʻe o ke au e hoʻouka nei.

ʻIke mākou i ka hoʻohālikelike ʻana o kahi hōʻailona e pili ana i ka loli o ka impedance i ʻike ai ka hōʻailona, ​​no laila no ke kālailai ʻana, e nānā i ka hoʻololi o ka impedance a ka capacitance e hana ai. I ka pae mua o ka hoʻouka ʻana o ka capacitor, hōʻike ʻia ka impedance penei:

Maʻaneʻi, ʻo DV maoli ka loli uila o ka hōʻailona ʻanuʻu, ʻo dt ke ala piʻi ʻana o ka hōʻailona, ​​a lilo ka mana impedance capacitance:

Mai kēia kumumanaʻo, hiki iā mākou ke kiʻi i kahi ʻike nui, ke hoʻopili ʻia ka hōʻailona i ka pae mua ma nā wēlau ʻelua o ka capacitor, pili ka impedance o ka capacitor i ka manawa piʻi ala a me kona capacitance.

ʻO ka maʻamau i ka pae mua o ka hoʻouka ʻana o ka capacitor, heʻuʻuku ka impedance, ʻoi aku ka liʻiliʻi ma mua o ka impedance ʻano o nā uea. Aia ke aniani maikaʻi ʻole o ka hōʻailona ma ka capacitor, a ua hoʻopili ʻia ka hōʻailona uila maikaʻi ʻole me ka hōʻailona kumu, e hopena ana i ka hiolo o ka hōʻailona ma ka transmitter a me ka monotonic ʻole o ka hōʻailona ma ka transmitter.

No ka hopena e loaʻa ana, ma hope o ka hōʻea ʻana o ka hōʻailona i ka hopena loaʻa, kū ka noʻonoʻo maikaʻi, hiki i ka hōʻailona aniani i ke kūlana capacitor, kū kēlā ʻano o ke aniani maikaʻi ʻole, a ʻo ka uila uila noonoo ʻole i hōʻike ʻia i ka hopena e loaʻa ai ka hōʻailona ma ka loaʻa hoʻopau e hana i downrush.

I mea e emi ai ke kani kani ma lalo o 5% o ke kani uila, i hiki ke ʻoluʻolu no ka hōʻailona, ​​pono ma lalo o 10% ka loli impedance. No laila he aha ka impedance capacitance? ʻO ka impedance Capacitance kahi impedance like, a hiki iā mākou ke hoʻohana i ka formula impedance like a me ka coefficient formula coefficient e hoʻoholo i kāna pae. No kēia impedance like, makemake mākou i ka impedance capacitance e like ka nui me ka hiki. Ke kuhi nei ka impedance capacitance ʻo K mau manawa o ka pilina PCB pilina impedance, hiki ke kiʻi ʻia ka impedance e ka hōʻailona ma ka capacitor e like me ke ʻano impedance like:

ʻO ia, e like me kēia helu kūpono, pono ka impedance o ka capacitor ma kahi o 9 mau manawa i ka impedance ʻano o ka PCB. I ka ʻoiaʻiʻo, e like me ka hoʻopiʻi ʻana o ka capacitor, hoʻonui ka impedance o ka capacitor a ʻaʻole mau i ka impedance haʻahaʻa loa. Eia hou, hiki i kēlā me kēia hāmeʻa ke loaʻa ka inductance parasite, kahi e hoʻonui ai i ka impedance. No laila, hiki ke hoʻomaha i kēia palena ʻeiwa pā. I ke kūkā e hiki mai ana, e kuhi ʻoe he 5 mau manawa ka palena.

Me kahi hōʻailona o ka impedance, hiki iā mākou ke hoʻoholo i ka nui o ka capacitance e hiki ai ke hoʻomanawanui. ʻO ka impedance ʻano 50 ohms ma ka papa kaapuni ka mea maʻamau, no laila ua hoʻohana wau i 50 ohm e helu ai.

Hoʻoholo ʻia:

I kēia hihia, inā he 1ns ka manawa piʻi ala, ʻoi aku ka liʻiliʻi o ka capacitance ma mua o 4 picograms. Ma ka ʻokoʻa, inā 4 capacogram ka capacitance, ʻo 1ns ka manawa ʻoi loa o ka hōʻailona. Inā 0.5ns ka manawa piʻi o ka hōʻailona, ​​e pilikia kēia 4 picograms capacitance.

ʻO ka helu ʻana ma aneʻi wale nō e wehewehe i ka mana o ka capacitance, paʻakikī loa ke kaapuni maoli, pono e noʻonoʻo ʻia nā mea hou aʻe, no laila inā ʻaʻole pololei ka helu ʻana ma aneʻi ʻaʻole ia he mea nui. ʻO ke kī e hoʻomaopopo pehea ka hopena o ka capacitance i ka hōʻailona ma o kēia helu. I ka manawa e ʻike ai mākou i ka hopena o kēlā me kēia mea ma ka papa kaapuni, hiki iā mākou ke hāʻawi i ke alakaʻi kūpono no ka hoʻolālā a ʻike pehea e kālailai ai i nā pilikia ke hiki mai lākou. Pono nā kuhi kūpono i ka hoʻohālikelike ʻana i nā polokalamu.

Ka Hopena:

1. ʻO ka ukana capacitive i ka wā o PCB e hoʻohuli nei i ke kumu o ka hopena transmitter e hana i ka downrush, a ʻo ka hōʻailona o ka hopena o ka mea loaʻa e hana pū i ka downrush.

2. Pili ka ahonui o ka capacitance i ka manawa piʻi o ka hōʻailona, ​​ʻo ka wikiwiki o ka piʻi ʻana o ka hōʻailona, ​​ʻo ka liʻiliʻi o ka hoʻomanawanui ʻana o ka capacitance.