Matlab Implementation of the Biquad

The two control parameters for this filter are

1. the center frequency $f_c$
2. the quality factor $Q$ (or bandwidth).

T = 1/44100;
Q = 20;
fc = 400;
Bw = fc/Q;

R = exp(-pi*Bw*T);

B = [1 0 -R];
A = [1 -2*R*cos(2*pi*fc*T) R*R];

[h, w] = freqz(B,A);

Use freqz, tf2zp and zplane to see how the spectrum corresponds to the plot of the poles and zeros in the z-plane.

Parameters can be changed in real-time, making this an efficient and ideal implementation for performance situations.