In this section, we will realize the designed IIR filter using direct form I and direct form II. We will then realize a higher-order IIR filter using a cascade form.
Realize the first-order digital highpass Butterworth filter
using a direct form I.
Solution:
From the transfer function, we can identify
Applying the direct form I developed in Chapter 6 results in the diagram in Figure 8.37.
The digital signal processing (DSP) equation for implementation is then given by
Program 8.14 lists the MATLAB implementation.
%Sample MATLAB codesample = 2:2:20; %Input test arrayx = [0 0]; % Input buffer [x(n) x(n?1)...]y = [0 0]; % Output buffer [y(n)y(n?1)...]b = [0.1936?0.1936]; % Numerator coefficients [b0 b1...]a = [1 0.6128]; % Denominator coefficients [1 a0 a1...]for n = 1:1:length(sample) % Processing loopfor k = 2:?1:2x (k) = x (k?1); % Shift the input by one sampley (k) = y (k?1); %...
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