CZ2IIR return a,b IIR filter coefficients for a complex zero designed using the bilinear transform. %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% DESCRIPTION: CZ2IIR return a,b IIR filter coefficients for a complex zero designed using the bilinear transform. CALL: [a,b] = cz2iir(z, fs) INPUTS: z - zero object fs - the sample rate for the filter VERSION: $Id: cz2iir.m,v 1.2 2007/07/18 13:58:45 ingo Exp $ HISTORY: 03-04-2007 Hewitson Creation %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
0001 function [a,b] = cz2iir(z, fs) 0002 % CZ2IIR return a,b IIR filter coefficients for a complex zero designed using the bilinear transform. 0003 % 0004 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 0005 % 0006 % DESCRIPTION: CZ2IIR return a,b IIR filter coefficients for a complex zero 0007 % designed using the bilinear transform. 0008 % 0009 % CALL: [a,b] = cz2iir(z, fs) 0010 % 0011 % INPUTS: z - zero object 0012 % fs - the sample rate for the filter 0013 % 0014 % VERSION: $Id: cz2iir.m,v 1.2 2007/07/18 13:58:45 ingo Exp $ 0015 % 0016 % HISTORY: 03-04-2007 Hewitson 0017 % Creation 0018 % 0019 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 0020 0021 f0 = get(z, 'f'); 0022 q = get(z, 'q'); 0023 0024 w0 = f0*2*pi; 0025 w02 = w0^2; 0026 0027 a(1) = (-q*w02/2 - 2*q*fs*fs - w0*fs) / (q*w02); 0028 a(2) = (-w02+4*fs*fs) / w02; 0029 a(3) = (-q*w02/2 - 2*q*fs*fs + w0*fs) / (q*w02); 0030 0031 b(1) = 1; 0032 b(2) = -2; 0033 b(3) = -1; 0034 0035 % END