sallen key filter

Discussion in 'General Electronics Chat' started by vustudent, Nov 2, 2010.

  1. vustudent

    Thread Starter Active Member

    Mar 11, 2009
    38
    0
    Why the op amp used in a sallen key filter circuit is to be unity gain?
     
  2. t_n_k

    AAC Fanatic!

    Mar 6, 2009
    5,448
    782
  3. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    For a Butterworth lowpass filter:
    1) If the opamp has a gain of 1 then the feedback capacitor must have a value that is double the value of the capacitor to ground.
    2) If the opamp has a gain of about 1.6 then the capacitors and the resistors can have equal values.
     
Loading...