ABSTRACT
Passive filters are frequency-selective circuits constructed using only passive components such as resistors,
capacitors, and inductors. Other passive components such as distributed RC components, quartz crystals, and
surface acoustic wave (SAW) devices are also used in special-purpose filters. However, active filters involve
active components such as operational amplifiers (op amps) or discrete transistors. Compared to their passive
counterparts, active filters are better suited to circuit board implementation because they avoid the need for
inductors. Switched capacitor filters are best suited to monolithic integration because they avoid the need for
large-valued passive components (resistors and capacitors).
