Re: What is the difference equation of a Butterworth filter?

*To*: mathgroup at smc.vnet.net*Subject*: [mg27480] Re: What is the difference equation of a Butterworth filter?*From*: "John Doty" <jpd at w-d.org>*Date*: Tue, 27 Feb 2001 00:37:34 -0500 (EST)*References*: <972ge7$4kr@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

In article <972ge7$4kr at smc.vnet.net>, "Elias Kyriakides" <elias_kyriakides at hotmail.com> wrote: > Can anybody provide me with the difference equation of a Butterworth > filter? e.g. something like y[n] = a1x[n] +a2x[n-1] etc > > Thanks, Elias > > No. The Butterworth filter has a frequency response that is a rational function of finite order. Such a response can be realized by differential equations, but not by difference equations. The Buttterworth filter is a classic utilizing the capabilities of analog electronic components. Attempting to approximate it digitally probably isn't a particularly useful exercise: digital filters have different capabilities and limitations. -- | John Doty "You can't confuse me, that's my job." | Home: jpd at w-d.org | Work: jpd at space.mit.edu