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?

Cheers,
Brian

 

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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.
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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?

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.