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A Comparison of Passive Filters and Active Filters

The Advantages of Each Filter Type:

PASSIVE ACTIVE
  • no power supply required
  • can handle large currents and high voltages
  • very reliable
  • least number of components for given filter
  • noise arises from resistances only
  • no bandwidth limitation
  • no inductors
  • easier to design
  • high Zin, low Zout for minimal loading
  • can produce high gains
  • generally easier to tune
  • small in size and weight

The Disadvantages of Each Filter Type:

PASSIVE ACTIVE
  • inductors large for lower frequencies
  • some inductors (non-toroidal) may require shielding
  • limited standard sizes, often requiring variable inductors and therefore tuning
  • low tolerance inductors (1-2%) very expensive
  • must be designed with consideration to input and output loading
  • generally not amenable to miniaturization
  • no power gain possible
  • no voltage gain
  • power supply required
  • susceptible to intermodulation, oscillations
  • susceptible to parasitics from DC output offset voltage and input bias currents
  • op amp gain bandwidth constrained
  • op amp slew rate constrained
  • can require many components