Signal reflection inogona kukonzera kurira. Yakajairika kurira kwechiratidzo inoratidzwa muMufananidzo 1.

Saka kurira kwechiratidzo kunoitika sei?

Sezvambotaurwa, kana shanduko ye impedance ikanzwika panguva yekufambisa kwechiratidzo, chiratidzo chechiratidzo chichaitika. Ichi chiratidzo chinogona kunge chiri chiratidzo chinotumirwa nemutyairi, kana chinogona kunge chiri chiratidzo chinoratidzwa kubva kumagumo. Zvinoenderana neanoratidzira coefficient formula, kana iyo chiratidzo ichinzwa kuti iyo impedance inova diki, kutarisisa kwakashata kuchaitika, uye iyo inoratidzwa yakashata voltage ichaita kuti chiratidzo chiderere. Chiratidzo chinoratidzwa kakawanda pakati pemutyairi uye kuremerwa kure, uye mhedzisiro iri kurira kwechiratidzo. Iyo yekubuda impedance yemachipi mazhinji yakadzikira. Kana iyo yakabuda impedance iri shoma pane hunhu impedance ye PCB trace, kurira kwechiratidzo kunozoitika kana pasina kubviswa kunobva.

Maitiro ekuridza chiratidzo anogona kutsanangurwa intuitively neiyo bounce diagram. Tichifunga kuti iyo inoburitsa impedance yekugumisira kwekutyaira ndeye gumi ohms, uye hunhu hwePCB trace ndeye 10 ohms (inogona kugadziridzwa nekuchinja hupamhi hwePCB trace, ukobvu hwedielectric pakati pePCB trace uye referensi yemukati. ndege), kuti zvive nyore kuongorora, fungidzira kuti kure kure kwakavhurika , Kureva kuti, kure-kumagumo impedance isingaperi. Iyo dhiraivha yekupedzisira inotumira chiratidzo che 50V voltage. Ngatiteverei chiratidzo uye timhanye nemutsetse wekutumira uyu kamwe kuti tione zvakaitika. Kuti zvive nyore kuongororwa, pesvedzero yeparasitic capacitance uye parasitic inductance yemutsetse wekutapurirana inoregeredzwa, uye chete mitoro inodzivirira inofungidzirwa. Mufananidzo 3.3 dhiyabhorosi dhayagiramu yekufungisisa.

Kuratidzira kwekutanga: chiratidzo chinotumirwa kunze kubva ku chip, mushure megumi ohm kubuda impedance uye 10 ohm PCB hunhu impedance, chiratidzo chakawedzerwa kune PCB trace ndiyo voltage panzvimbo A 50 * 3.3 / (50 + 10) = 50 V. Kuendesa kunzvimbo iri kure B, nokuti pfungwa B yakazaruka, iyo impedance isingagumi, uye kuenzanisa kwekuenzanisa ndeye 2.75, kureva kuti, zviratidzo zvose zvinoratidzwa, uye chiratidzo chinoratidzwa zvakare 1V. Panguva ino, iyo yakayerwa voltage panzvimbo B ndeye 2.75 + 2.75 = 2.75V.

Chechipiri fungidziro: iyo 2.75V inoratidzira voltage inodzokera kunzvimbo A, iyo impedance inoshanduka kubva pa50 ohms kuenda ku10 ohms, kuratidzwa kwakashata kunoitika, iyo inoratidzwa voltage papoint A iri -1.83V, voltage inosvika poindi B, uye kuratidzwa kunoitika zvakare, uye mhepo inoratidzwa ndeye -1.83 V. Panguva ino, iyo yakayerwa voltage panzvimbo B ndeye 5.5-1.83-1.83 = 1.84V.

Chiratidzo chechitatu: Iyo -1.83V voltage inoratidzwa kubva pachinhanho B inosvika padanho A, uye kuratidzira kwakashata kunoitika zvakare, uye iyo inoratidzwa voltage i1.22V. Kana magetsi asvika panzvimbo B, fungidziro yenguva dzose inoitika zvakare, uye iyo inoratidzwa voltage ndeye 1.22V. Panguva ino, iyo yakayerwa voltage panzvimbo B ndeye 1.84 + 1.22 + 1.22 = 4.28V.

Mukutenderera uku, iyo voltage inotaridzwa inobhururuka ichidzoka nekudzoka pakati pepoint A nepoint B, zvichiita kuti voltage papoint B isagadzikane. Tarisa voltage panzvimbo B: 5.5V-> 1.84V-> 4.28V->……, zvinogona kuonekwa kuti voltage panzvimbo B inoshanduka ichikwira nekudzika, inova chiratidzo chekurira.

Kurira kwechiratidzo muPCB kunoitika sei?

Mhedzisiro yechiratidzo chekurira inokonzerwa nekufungidzira kusina kunaka, uye muparadzi achiri impedance shanduko, iyo zvakare impedance! Paunenge uchidzidza nyaya dzekuvimbika kwechiratidzo, gara uchiteerera kune nyaya dze impedance.

Kurira kwechiratidzo pamagumo emutoro kuchakanganisa zvakanyanya kugamuchirwa kwechiratidzo uye kukonzera zvikanganiso zvepfungwa, izvo zvinofanirwa kudzikiswa kana kubviswa. Naizvozvo, kumisikidzwa kwekufananidza kwe impedance kunofanirwa kuitwa kune mitsara refu yekutapurirana.