# Electronics Fundamentals/Electronic Filter/Band Pass Filter

## LR + CR Band Pass Filter

### Characteristics

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

Band Pass or band of frequencies that has a stable voltage over a band of frequencies

${\displaystyle {\frac {R}{L}}-{\frac {1}{RC}}}$

Provided that

${\displaystyle {\frac {1}{RC}}>{\frac {R}{L}}}$

## RC + RL Band Pass Filter

### Characteristics

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

Band Pass or band of frequencies that has a stable voltage

${\displaystyle {\frac {1}{RC}}-{\frac {R}{L}}}$

Provided that

${\displaystyle {\frac {R}{L}}>{\frac {1}{RC}}}$

## Summary

Band Pass Filter has stable voltage over a band of frequencies

${\displaystyle {\frac {R}{L}}-{\frac {1}{RC}}}$
Provided that ${\displaystyle {\frac {1}{RC}}>{\frac {R}{L}}}$ for the LR + CR configuration
${\displaystyle {\frac {1}{RC}}-{\frac {R}{L}}}$
Provided that . ${\displaystyle {\frac {R}{L}}>{\frac {1}{RC}}}$ for the CR + LR + configuration