Low-pass filter
A low-pass filter is an electronic filter that passes the frequency component of a signal below a certain value (cutoff frequency). The frequency component above that certain value will be suppressed to almost zero.
Low-pass Filter Media
The sinc function, the time-domain impulse response of an ideal low-pass filter. The ripples of a true sinc extend infinitely to the left and right while getting smaller and smaller, but this particular graph is truncated.
Plot of the gain of Butterworth low-pass filters of orders 1 through 5, with cutoff frequency \omega_0 = 1. Note that the slope is 20n dB/decade where n is the filter order.
Passive, first order low-pass RC filter
A third-order low-pass filter (Cauer topology). The filter becomes a Butterworth filter with cutoff frequency ωc=1 when (for example) C2=4/3 farad, R4=1 ohm, L1=3/2 henry and L3=1/2 henry.
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