Filter Circuit

Filter Circuit:

  Filters are electrical networks used to separate alternating from direct current components or to separate a group of 

A.C. components included within a particular frequency range from those lying outside this range. So a filter can 

be defined as a network that in its ideal form has at least one range of frequency in which the attenuation is zero 

(pass hand) and at least one range of frequency in which the attenuation is infinite (attenuation band). The 

frequencies which separate a pass band and attenuation hand are called cut-off frequencies. To achieve the desired 

effect, the filter is designed to provide a low attenuation for frequency components within a particular pass band  

range and a high attenuation at frequencies within other stop band ranges. The networks provide a uniform response 

over a wide range of frequencies than that obtained with resonant circuits. Filters are commonly classified in

accordance with their selectivity characteristics as below :

(a) A low pass filter. It transmits all frequencies below a limiting frequency 𝑓𝑐

. known as cut-off frequency. and 

stops all these above this frequency.

(b) A high pass filter. It passes frequencies above the cut-off freque

ncy and stops all those below this frequency. 

(c) A band pass filter. It passes frequencies in a particular hand between two cut-off frequencies and stops those 

above and below this band limit. 

(d) A band elimination filter. It stops frequencies within a specified band and passes those above and below the 

units of this hand.