Passive Cheebtsam hauv RF Circuits
Resistors, capacitor, kav hlau txais xov. . . . Kawm txog cov khoom siv passive siv hauv RF systems.
RF systems tsis yog qhov txawv ntawm lwm hom hluav taws xob circuits. Tib txoj cai ntawm physics siv, thiab yog li cov khoom siv yooj yim siv hauv RF designs kuj pom muaj nyob rau hauv digital circuits thiab low-frequency analog circuits.
Txawm li cas los xij, RF tsim muaj qhov tshwj xeeb ntawm cov teeb meem thiab cov hom phiaj, thiab yog li cov yam ntxwv thiab kev siv ntawm cov khoom hu rau kev txiav txim siab tshwj xeeb thaum peb ua haujlwm hauv cov ntsiab lus ntawm RF. Tsis tas li ntawd, qee qhov kev sib xyaw ua ke ua haujlwm tau zoo heev rau cov tshuab RF-lawv tsis siv nyob rau hauv qis zaus circuits thiab tej zaum yuav tsis to taub zoo los ntawm cov neeg uas tsis tshua muaj kev paub txog RF tsim cov tswv yim.
Peb feem ntau categorize Cheebtsam raws li active los yog passive, thiab txoj kev no yog sib npaug zos siv nyob rau hauv lub realm ntawm RF. Cov xov xwm sib tham txog cov khoom tsis muaj zog tshwj xeeb hauv kev cuam tshuam nrog RF circuits, thiab nplooj ntawv tom ntej no suav nrog cov khoom siv.
Capacitors
Ib qho zoo tagnrho capacitor yuav muab cov kev ua haujlwm zoo ib yam rau 1 Hz teeb liab thiab 1 GHz teeb liab. Tab sis cov khoom siv tsis yog qhov zoo tagnrho, thiab qhov tsis zoo ntawm lub capacitor tuaj yeem yog qhov tseem ceeb ntawm cov khoom siv siab.
"C" sib haum mus rau qhov zoo tagnrho capacitor uas yog faus ntawm ntau cov kab mob parasitic. Peb muaj kev tsis sib haum xeeb ntawm daim hlau (RD), series tsis kam (RS), series inductance (LS), thiab parallel capacitance (CP) ntawm PCB pads thiab lub dav hlau hauv av (peb xav tias cov khoom siv saum npoo av; ntxiv rau qhov no tom qab).
Qhov tseem ceeb tshaj plaws nonideality thaum peb ua hauj lwm nrog high-frequency signals yog inductance. Peb cia siab tias qhov impedance ntawm lub capacitor yuav txo qis thaum qhov zaus nce, tab sis muaj cov kab mob parasitic inductance ua rau lub impedance poob rau ntawm tus kheej-resonant zaus thiab tom qab ntawd pib nce:
Resistor, thiab al.
Txawm tias cov resistors tuaj yeem ua teeb meem ntawm qhov ntau zaus, vim tias lawv muaj cov inductance, sib npaug capacitance, thiab cov capacitance raug cuam tshuam nrog PCB pads.
Thiab qhov no coj los ua ib qho tseem ceeb: thaum koj ua haujlwm nrog ntau zaus, cov kab mob parasitic circuits nyob txhua qhov chaw. Tsis muaj teeb meem npaum li cas yooj yim lossis zoo tagnrho cov khoom tiv thaiv, nws tseem yuav tsum tau ntim thiab soldered rau PCB, thiab qhov tshwm sim yog kab mob. Tib yam siv rau lwm yam kev tivthaiv: yog tias nws tau ntim thiab soldered rau lub rooj tsavxwm, cov kab mob parasitic muaj nyob.
Crystals
Lub ntsiab lus ntawm RF yog tswj cov teeb liab siab zaus kom lawv xa cov ntaub ntawv, tab sis ua ntej peb tswj peb yuav tsum tsim. Raws li nyob rau hauv lwm yam circuits, crystals yog ib qho tseem ceeb txhais tau tias ntawm tsim ib tug ruaj khov zaus siv.
Txawm li cas los xij, hauv cov qauv tsim digital thiab sib xyaw ua ke, feem ntau yog cov ntaub ntawv uas siv lead ua-raws li circuits tiag tiag tsis xav tau qhov tseeb uas siv lead ua tuaj yeem muab tau, thiab yog li nws yooj yim los ua tsis quav ntsej txog kev xaiv siv lead ua. Ib qho RF Circuit Court, nyob rau hauv sib piv, tej zaum yuav muaj nruj zaus yuav tsum tau, thiab qhov no hu rau tsis tau tsuas yog thawj zaus precision tab sis kuj zaus stability.
Lub oscillation zaus ntawm ib tug zoo tib yam siv lead ua yog rhiab rau kub variations. Qhov tshwm sim tsis txaus ntseeg tsim teeb meem rau cov tshuab RF, tshwj xeeb tshaj yog cov tshuab uas yuav raug cuam tshuam rau qhov hloov pauv loj hauv qhov kub thiab txias. Yog li, lub kaw lus yuav xav tau TCXO, piv txwv li, qhov kub-compensated crystal oscillator. Cov khoom siv no suav nrog cov khoom siv hluav taws xob uas them nyiaj rau cov siv lead ua qhov sib txawv:
Kav hlau txais xov
Lub kav hlau txais xov yog ib qho khoom siv tsis muaj zog uas yog siv los hloov RF hluav taws xob teeb liab mus rau hauv hluav taws xob hluav taws xob hluav taws xob (EMR), lossis lwm yam. Nrog rau lwm cov khoom siv thiab cov neeg xyuas pib peb sim txo qhov cuam tshuam ntawm EMR, thiab nrog cov kav hlau txais xov peb sim ua kom zoo dua cov tiam lossis txais tos ntawm EMR nrog rau kev xav tau ntawm daim ntawv thov.
Kav hlau txais xov science tsis yog qhov yooj yim. Ntau yam cuam tshuam rau cov txheej txheem ntawm kev xaiv lossis tsim lub kav hlau txais xov uas zoo rau ib daim ntawv thov tshwj xeeb. AAC muaj ob kab lus (nias ntawm no thiab ntawm no) uas muab cov lus qhia zoo heev rau cov ntsiab lus kav hlau txais xov.
Cov zaus ntau dua yog nrog los ntawm ntau yam kev sib tw tsim, txawm hais tias cov kav hlau txais xov ib feem ntawm lub kaw lus tuaj yeem ua teeb meem tsawg dua li qhov zaus nce, vim tias ntau zaus tso cai rau kev siv cov kav hlau txais xov luv. Niaj hnub no nws yog ib qho kev siv "chip kav hlau txais xov," uas yog soldered rau PCB zoo li cov khoom nto-mount, lossis PCB kav hlau txais xov, uas yog tsim los ntawm kev sib koom ua ke tshwj xeeb tsim kab rau hauv PCB layout.
Cov ntsiab lus
Qee cov khoom siv feem ntau tsuas yog hauv RF daim ntawv thov, thiab lwm tus yuav tsum tau xaiv thiab ua tib zoo siv ntau dua vim lawv tus cwj pwm tsis zoo.
Passive Cheebtsam nthuav tawm cov lus teb tsis zoo raws li qhov tshwm sim ntawm parasitic inductance thiab capacitance.
RF daim ntawv thov yuav xav tau cov khoom siv lead ua uas muaj tseeb dua thiab / lossis ruaj khov dua li cov khoom siv uas siv hauv digital circuits.
Kav hlau txais xov yog cov khoom tseem ceeb uas yuav tsum tau xaiv raws li cov yam ntxwv thiab cov kev xav tau ntawm RF system.
Si Chuan Keenlion Microwave ib qho kev xaiv loj hauv qhov nqaim thiab kev teeb tsa dav dav, suav nrog zaus ntawm 0.5 txog 50 GHz. Lawv tau tsim los tswj los ntawm 10 mus rau 30 watts input zog hauv 50-ohm kis tau tus mob. Microstrip los yog stripline designs yog siv, thiab optimized rau kev ua tau zoo tshaj plaws.
Post lub sij hawm: Nov-03-2022
