Ideal Component Values for Sallen-Key LPF?

Discussion in 'The Projects Forum' started by NullPoint, Nov 5, 2014.

  1. NullPoint

    Thread Starter New Member

    Jul 16, 2011
    Hi all,

    I'm trying to build a sallen-key LPF with a fc of ~2Hz. I'm a bit confused about how to pick the right component values and the whole Q thing.

    For non-Sallen key topology LPF, I was using 82K and 1.0uF components.

    Also, this circuit is to be used as a non-ideal integrator. Is the sallen-key topology a good fit or am I better off with a more traditional active LPF?

  2. crutschow


    Mar 14, 2008
    The "Q thing" is determined by the type of filter characteristic you want (Butterworth, Besel, etc.). An easy way to design them is to use a program such as the free FilterPro download from Texas Instruments.

    A Sallen-Key is a "traditional active LPF" along with multiple-feedback, state-variable, and biquad types. What is best for your application, I can't answer, without knowing more about what signal you are trying to integrate.