Electronics Handbook/Devices/Filter/Low Pass Filter

RC

Configuration

Characteristics

$\frac{V_o}{V_i}=\frac{\frac{1}{j\omega C}}{R+\frac{1}{j\omega C}}=\frac{1}{1+j\omega T}$

$T=RC$

${\omega }_o=\frac{1}{T}=\frac{1}{RC}$

LR

Characteristics

$\frac{V_o}{V_i}=\frac{R}{R+j\omega L}=\frac{1}{1+j\omega T}$

$T=RC$

${\omega }_o=\frac{j\omega L}{R+j\omega L}=\frac{1}{1+j\omega T}$

Summary

The two configurations above can be used for /Low Pass Filter/ which has stable voltage which does not change with frequency over low range of frequencies