3 db bandwidth

Replies

• 

  Jeffrey Arulraj

  the answer is simple the amplifier gain at lower cut off and upper cut off frequency is 1/ root 2 times the actual gain in the mid frequency region
  
  the 20(log(1/root2)) is -3 dB
  
  so we use it for drawing the line
• 

  Jeffrey Arulraj

  check this out frequency response of lower frequency region
  
  Av=1/(1+j(f/f1))
  where f= frequency of the signal
  f1= lower cut off frequency
  
  when f=f1
  |Av|=1/root(2)
  
  this is also true for higher frequency respone
  
  
  PS: refer electronic circuits and devices by S. Salivahanan for more info
  
  i took this from there