A Band Pass filter can be realized starting from a simple RLC to a high end DSP. Where do you want to fit in ?

And what band of frequencies would you want to pass on ? And how sharp or shallow you want the cut off to be ?

And once you know the above, try Prof.Google - he is a well informed fellow !!

And I would'nt call it off topic - there are lots of 8051 mixed signal derivatives that can use a BP in the front end.

Raghu