Active and Passive Filters

Passive filters with sharp falloff rates use combinations of inductors and capacitors to achieve good results. Simple RC circuitry can produce filters with a 6 decibel per octave falloff rate.  These simple filters work fine for filtering out signals much higher or lower than the range of the signal being conditioned. If you want to achieve a much higher drop off rate you must use a combination of inductors and capacitors in your filters.  Observe operation and plot output verses frequency Chepyshev filter below.  Estimate how many decibels per octave the falloff rate is. 

 

 

 

 

 

 Above we see a schematic of an active low pass filter.  Note that it only requires capacitors and resistors.  This makes it inexpensive to produce.  To learn more about this circuit.  Click Here!