```

Vout ──[ R]──●───────────  ADC
                 |
                 |
                === C
                 |
                GND
```

For a one pole low pass filter where $\tau=RC$ and $\omega$ is angular velocity in radians:

$$|H(j\omega)| = \frac{1}{\sqrt{1+{(\omega \tau)}^2}}$$
The -3dB point is when $\omega \tau = 1$, i.e. magnitude response is $\frac{1}{\sqrt{2}} = 0.707$


This cut off frequency is defined as $$\omega_{c} = \frac{1}{\tau}, \; f_{c} =\frac{1}{2 \pi \tau}$$

For a Laplace transform derivation see [[Worked Example RC Low Pass]]

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