Muzviitiko zvakawanda, PCB wiring ichapfuura nepakati pemaburi, bvunzo nzvimbo mapads, mapfupi stub mitsara, nezvimwe, zvese izvo zvine parasitic capacitance, izvo zvinokanganisa kukanganisa chiratidzo. Iko kukanganisa kweiyo capacitance pachiratidzo kunofanirwa kuongororwa kubva kumagumo anotumira uye kumagumo ekugamuchira, uye ine mhedzisiro panotangira nepanoperera poindi.

Chekutanga tinya kuti uone kukanganisa kweanotumira chiratidzo. Kana danho rinokwira nekukurumidza richisvika pane iyo capacitor, iyo capacitor inobhadhariswa nekukurumidza. Iyo yekuchaja yazvino inoenderana nekukurumidza kweiyo chiratidzo vhiri inokwira. Iyo yekuchaja yazvino fomula ndeiyi: I = C * dV / dt. Iyo yakakwira iyo capacitance, iyo yakakwira iyo yekuchaja yazvino, iyo inokurumidza iyo chiratidzo yekukwira nguva, diki dt, zvakare inoita iyo yakakwira iyo yekuchaja yazvino.

Isu tinoziva kuti kuratidzwa kwechiratidzo kune hukama neshanduko yemhedheni iyo inonzwa chiratidzo, saka pakuongorora, ngatitarisei shanduko yemhedheni iyo iyo capacitance inokonzeresa. Panhanho yekutanga ye capacitor kuchaja, impedance inoratidzwa se:

Pano, dV ndiyo chaizvo shanduko yemagetsi yedanho rechiratidzo, dt ndiyo chiratidzo yekukwira nguva, uye iyo capacitance impedance fomula inova:

Kubva pane iyi fomula, tinogona kuwana ruzivo rwakakosha kwazvo, kana danho redanho rikaiswa padanho rekutanga kumacheto ese eiyo capacitor, iyo impedance yeiyo capacitor inoenderana nenguva yekukwira kwechiratidzo uye kugona kwayo.

Kazhinji padanho rekutanga re capacitor kuchaja, iyo impedance idiki kwazvo, yakaderera pane hunhu impedance yewiring. Kuratidzira kusarongeka kwechiratidzo kunoitika pane iyo capacitor, uye isina kunaka magetsi chiratidzo chakakwidziridzwa nechiratidzo chekutanga, zvichikonzera kudzikisira kwechiratidzo pane anotepfenyurisa uye isiri-monotonic yechiratidzo pane anotumira.

Yezve kuguma, mushure mekunge chiratidzo chasvika kumagumo ekugashira, kuratidzwa kwakanaka kunoitika, chiratidzo chinoratidzwa chinosvika pa capacitor chinzvimbo, rudzi irworwo rwekuratidzira kwakashata kunoitika, uye isina kunaka yekuratidzira voltage inoratidzirwa kumashure kumagumo ekugashira inokonzeresawo chiratidzo pakugamuchira. end kugadzira kuburitsa pasi.

Kuti ruzha runoratidzwa ruve pasi pe5% yeiyo voltage swing, iyo inoshivira kune iyo chiratidzo, iyo impedance shanduko inofanira kunge iri pasi pe10%. Saka chii chinofanirwa kuve iyo capacitance impedance? Capacitance impedance yakafanana impedance, uye isu tinokwanisa kushandisa yakafanana impedance fomula uye yekuratidzira coefficient fomula kuti tione huwandu hwayo. Kune ino impedance inoenderana, isu tinoda kuti iyo capacitance impedance ive yakakura sezvinobvira. Kufunga kuti iyo capacitance impedance iri K nguva dzePCB wiring hunhu impedance, iyo impedance inonzwa nechiratidzo paiyo capacitor inogona kuwanikwa zvinoenderana neyakafanana impedance fomula:

Ndokunge, maererano neiyi chaiyo kukarukureta, iyo impedance yeiyo capacitor inofanirwa kuve ingangoita ka9 iyo mamirire eiyo PCB. Muchokwadi, sezvo iyo capacitor ichibhadhariswa, iyo impedance yeiyo capacitor inowedzera uye haigare ichingove yakaderera impedance. Uye zvakare, chishandiso chimwe nechimwe chinogona kuve nehutachiona inductance, iyo inowedzera iyo impedance. Saka iyi mipfumbamwe-mipimo inogona kurerukirwa. Mukukurukurirana kunotevera, fungidzira kuti muganho wacho kashanu.

Nechi chiratidzo chemhedheni, tinogona kuona kuti ingani capacitance inogona kutsungirira. Iyo makumi mashanu ohms hunhu impedance pane redunhu bhodhi yakajairika, saka ini ndaishandisa makumi mashanu ohms kuiverenga.

Zvinogumiswa kuti:

Mune ino kesi, kana iyo chiratidzo yekukwira nguva iri 1ns, iyo capacitance iri pasi pe4 mapikicha. Zvakare, kana iyo capacitance iri 4 picograms, iyo chiratidzo yekukwira nguva iri 1ns zvakanyanya. Kana iyo chiratidzo yekukwira nguva iri 0.5ns, iyi ina mapikicha capacitance inokonzeresa matambudziko.

Kukarukureta apa ndekwe kungotsanangura simba remagetsi, dunhu chairo rakaomarara, zvimwe zvinhu zvinoda kutariswa, saka kunyangwe kuverenga uko kuri kwechokwadi hakukoshi. Chinokosha ndechekuti unzwisise kuti kugona kugona kunokanganisa sei chiratidzo kuburikidza neiyi kuverenga. Kana tangova nekunzwisisa kwekunzwisisa kwechinhu chimwe nechimwe pabhodhi redunhu, tinokwanisa kupa nhungamiro inodikanwa kune dhizaini uye nekuziva maitiro ekuongorora matambudziko kana achinge aitika. Kufungidzira kwakarurama kunoda kutevedzera software.

mhedziso:

1. Iyo inokwenenzvera mutoro panguva yePBB routing inokonzeresa kuti chiratidzo chekutumira magumo kuburitsa kudonha, uye chiratidzo cheanogamuchira magumo chichagadzira zvakare kudonha.

2. Iko kushivirira kwe capacitance kunoenderana neiyo chiratidzo yekukwira nguva, iyo inokurumidza iyo chiratidzo yekukwira nguva, idiki iyo shiviriro yeiyo capacitance.