I need for use in a telephonic circuit, and it must have the telephonic band width, 300 to 3400 hz, 0 to -2.5 dB of attenuation, and for 100Hz it must be better than -30dB.
i mean you should use some of the development soft for filters. Se at the www pages of LInear Technology or Maxim or other manufactors for filter IC's.
In the net you will find moch more of filter soft for your project.