bandpass filter

[raf1208]

i need help designign a bandpass filter using opamps centered at 75 khz.

 

[cbarn24050]

Hi, we need a lot more imformation than that.

 

[rodar]

What you need is called a Delyiannis-Friend circuit

Build like this
Connect R2 between inverting (-) terminal and output of
op-amp.
Connect C1 between R1 and (-) inverting terminal of op-amp.
Connect C2 to between the R1 terminal above and op-amp output.
The loose end of R1 is the input. Ground the non inverting
terminal of the op-amp (+), and power the op-amp with
split supplies.

Make C1=C2=C
Resonant Freq = 1/(2*pi*sqr(R1*R2)*C)
Q factor = 0.5*(SQR(R2/R1)

Voltage gain is 2*Q^2 at resonance so an input
attenuator may be needed.

 

[230842]

If you contact me at chacon@des.icai.upco.es I can send you a schematic with two op-amps allowing a bandpass filtering with a bandwidth of about 1.3 khz and a quality factor of about 100 Julian