Implementation of basic 2-pole low-pass filter

1. How do you implement a digital low pass filter?
2. How does a second order low pass filter work?

How do you implement a digital low pass filter?

The most straightforward way to implement a digital filter is by convolving the input signal with the digital filter's impulse response. All possible linear filters can be made in this manner.

How does a second order low pass filter work?

A second order active low pass filter is one that decrease 12 dB / octave beyond the cut off frequency. At low frequency both capacitors appear open and the circuit becomes a voltage follower. As the frequency increase, the gain eventually starts to decrease until it is down 3 dB at the cut off frequency.