Cov lim dej tsis muaj zog yog tsim los ntawm cov khoom siv passive R, L, thiab C. Nws yog tsim los kom muaj qhov impedance qis heev ntawm qee zaus kom shunt lub harmonic tam sim no ntawm cov zaus sib xws. Nws tus cwj pwm hom yog muab ib tug passive harmonic tam sim no bypass channel. Cov ntxaij lim dej Passive tuaj yeem muab faib ua ob pawg: cov ntxaij lim dej tuned thiab cov lim dej siab dhau. Passive filters yog yooj yim nyob rau hauv cov qauv, tsis tshua muaj nqi thiab siab nyob rau hauv kev ntseeg tau ntawm kev ua hauj lwm, thiab yog dav siv passive harmonic tswj kev daws teeb meem.
Cov lim dej ua haujlwm yog tsim los ntawm cov khoom siv nquag (xws li kev ua haujlwm sib txuas ua ke) thiab R, C, tsis muaj inductance L, me me, lub teeb yuag. Lub lim dej ua haujlwm yog qhov ua kom muaj suab nrov nrog cov lus teb tshwj xeeb. Qhov qhib-voj voltage nce thiab input impedance ntawm kev ua hauj lwm amplifier yog siab heev, thiab cov zis kuj yog heev me me. Tom qab tsim cov lim dej ua haujlwm, nws muaj qee qhov voltage amplification thiab buffering nyhuv. Lub bandwidth ntawm kev sib xyaw ua haujlwm amplifier yog txwv, yog li kev khiav hauj lwm zaus ntawm lub lim dej tsis siab.
