Tunanin sigina na iya haifar da ƙara. Ana nuna sautin sigina na yau da kullun a hoto 1.

To ta yaya sautin siginar ke faruwa?

Kamar yadda aka ambata a baya, idan an ji canji a cikin rashin ƙarfi yayin watsa sigina, tunanin siginar zai faru. Wannan siginar na iya zama siginar da direba ya aiko, ko kuma yana iya zama siginar da aka nuna daga ƙarshen nesa. Dangane da dabarar haɓakar tunani, lokacin da siginar ya ji cewa impedance ya zama ƙarami, tunani mara kyau zai faru, kuma ƙarancin wutar lantarki da aka nuna zai haifar da siginar ƙasa. Ana nuna siginar sau da yawa tsakanin direba da kaya mai nisa, kuma sakamakon shine ƙarar sigina. Abubuwan da ake fitarwa na yawancin kwakwalwan kwamfuta yana da ƙasa sosai. Idan fitarwa impedance ne kasa da halayyar impedance na PCB alama, ƙarar sigina babu makawa zai faru idan babu ƙarewar tushe.

Za’a iya yin bayanin tsarin ƙarar siginar da hankali ta zanen billa. Tsammanin cewa tasirin fitarwa na ƙarshen drive ɗin shine 10 ohms, kuma halayen halayen PCB shine 50 ohms (ana iya daidaita su ta hanyar canza nisa na PCB, kauri na dielectric tsakanin alamar PCB da tunani na ciki. jirgin sama), don dacewa da bincike, ɗauka cewa ƙarshen nesa yana buɗewa , Wato, rashin ƙarfi mai nisa ba shi da iyaka. Ƙarshen motar yana watsa siginar ƙarfin lantarki na 3.3V. Bari mu bi siginar mu bi ta wannan layin watsa sau ɗaya don ganin abin da ya faru. Don dacewa da bincike, an yi watsi da tasirin tasirin parasitic capacitance da inductance parasitic na layin watsawa, kuma ana la’akari da nauyin juriya kawai. Hoto na 2 zane ne na tunani.

Tunani na farko: ana aika siginar daga guntu, bayan 10 ohm fitarwa impedance da 50 ohm PCB halayen impedance, siginar da aka ƙara a zahiri zuwa PCB alama ita ce ƙarfin lantarki a aya A 3.3 * 50 / (10 + 50) = 2.75 V. Watsawa zuwa wuri mai nisa B, saboda buɗaɗɗen batu B, impedance ba shi da iyaka, kuma ma’aunin tunani shine 1, wato, duk sigina suna nunawa, kuma siginar da aka nuna kuma shine 2.75V. A wannan lokacin, ma’aunin ƙarfin lantarki a batu B shine 2.75+2.75=5.5V.

Na biyu tunani: 2.75V nuna ƙarfin lantarki koma zuwa aya A, da impedance canje-canje daga 50 ohms zuwa 10 ohms, korau tunani faruwa, da nuna ƙarfin lantarki a batu A ne -1.83V, da ƙarfin lantarki kai batu B, da kuma tunani sake faruwa. kuma ƙarfin da aka nuna shine -1.83 V. A wannan lokacin, ƙarfin da aka auna a batu B shine 5.5-1.83-1.83 = 1.84V.

Tunani na uku: Ƙarfin wutar lantarki -1.83V wanda aka nuna daga batu B ya kai aya A, kuma mummunan tunani ya sake faruwa, kuma ƙarfin da aka nuna shine 1.22V. Lokacin da ƙarfin lantarki ya kai maki B, tunani na yau da kullun yana sake faruwa, kuma ƙarfin da aka nuna shine 1.22V. A wannan lokacin, ma’aunin ƙarfin lantarki a batu B shine 1.84+1.22+1.22=4.28V.

A cikin wannan sake zagayowar, ƙarfin lantarki da aka nuna yana billa baya da gaba tsakanin maki A da aya B, yana haifar da ƙarfin lantarki a batu B ya zama mara ƙarfi. Kula da wutar lantarki a batu B: 5.5V-> 1.84V->4.28V->……, za a iya ganin cewa ƙarfin lantarki a batu B zai yi jujjuya sama da ƙasa, wanda shine sautin sigina.

Yaya sautin siginar a cikin da’irar PCB ke faruwa?

Tushen sautin siginar yana haifar da mummunan tunani, kuma mai laifi har yanzu yana canzawa, wanda shine sake cikas! Lokacin nazarin batutuwan amincin sigina, koyaushe kula da lamuran impedance.

Ƙararrawar siginar a ƙarshen lodi zai tsoma baki sosai tare da liyafar siginar kuma ya haifar da kurakurai, wanda dole ne a rage ko kawar da shi. Don haka, dole ne a aiwatar da ƙarewar madaidaicin impedance don dogon layin watsawa.