Description of butterdesign

AutotunerPID Toolkit

butterdesign

PURPOSE

Butterworth analog lowpass filter design.

SYNOPSIS

function [B,A] = butterdesign(N,Wc)

DESCRIPTION

BUTTERDESIGN Butterworth analog lowpass filter design.
 
   [B,A] = BUTTERDESIGN(N,Wc) returns the numerator and denominator for an
   N-th order Butterworth analog with a bandwith Wc.
   The resulting filter has N poles around the circle of radius Wn in the
   left half plane, and no zeros. 

   Author:    William Spinelli ([e-mail])
   Copyright  2004 W.Spinelli
   $Revision: 1.0 $  $Date: 2004/02/27 12:00:00 $

CROSS-REFERENCE INFORMATION

This function calls:

This function is called by:

SOURCE CODE

0001 function [B,A] = butterdesign(N,Wc)
0002 %BUTTERDESIGN Butterworth analog lowpass filter design.
0003 %   [B,A] = BUTTERDESIGN(N,Wc) returns the numerator and denominator for an
0004 %   N-th order Butterworth analog with a bandwith Wc.
0005 %   The resulting filter has N poles around the circle of radius Wn in the
0006 %   left half plane, and no zeros.
0007 %
0008 %   Author:    William Spinelli ([e-mail])
0009 %   Copyright  2004 W.Spinelli
0010 %   $Revision: 1.0 $  $Date: 2004/02/27 12:00:00 $
0011 
0012 % Poles are on the circle of radius Wn in the left-half plane.
0013 p = Wc*exp(i*(pi*(1:2:N-1)/(2*N) + pi/2));
0014 p = [p; conj(p)];
0015 p = p(:);
0016 if rem(N,2)==1, p = [p; -Wc]; end
0017 A = poly(p);
0018 B = real(prod(-p));

bodePIDcompare

envgui

Generated on Wed 17-Mar-2004 09:29:44 by m2html © 2003