Electronics Handbook/Devices/Filter/Band Pass Filter

LR + CR

Characteristics

${\frac {V_{o}}{V_{i}}}=({\frac {1}{1+j\omega {\frac {L}{R}}}})({\frac {j\omega RC}{1+j\omega RC}})$

Band Pass or band of frequencies that has a stable voltage

${\frac {R}{L}}-{\frac {1}{RC}}$ provided that ${\frac {1}{RC}}>{\frac {R}{L}}$

RC - RL

Characteristics

${\frac {V_{o}}{V_{i}}}=({\frac {1}{1+j\omega RC}})({\frac {j\omega {\frac {L}{R}}}{1+j\omega {\frac {L}{R}}}})$

Band Pass or band of frequencies that has a stable voltage

${\frac {1}{RC}}-{\frac {R}{L}}$ provided that ${\frac {R}{L}}>{\frac {1}{RC}}$

Summary

The two configurations above can be used to construct Band Pass Filter which has stable frequency over a range of frequencies w1 - w2