Noise is a real pain especially when you are dealing with signals so weak to speak for themselves. And so are designing filters for them. Searching on the internet I came across a very old IC by Burr-Brown Corp. "UAF42" or the universal filter IC. Now sold by TI. Its a real good IC. you can design all sorts of filter with minimum componets. Comes with a free DOS based software for components calculation. And the best part TI gives free samples :)
Once you get the sofware....these are the steps to follow:
This is the most important section. Here you enter all the requirements. Depending upon your order of filter number of ICs increase. Now press F3
The above diagram is at page 6 fo the stated pdf
If you are making filters with higher order, more IC are required. In taht case the software with make the circuit as combination many subcircuits. Go through teh datasheet for more details. Enjoy!
