ABSTRACT
There are many methods for designing an IIR filter. A simple way is to use an analog-filter design, and then with a suitable transformation, transform the function H(s) to digital in the z-domain H(z). Analog filters are classified into the Butterworth filter and the Chebyshev filter. To design an IIR digital filter, bilinear transformation is used; this transformation transforms the left-hand-side of the s-plane into the interior inside of the unit circle in the z-plane. The main disadvantage of FIR filters is the possible requirement of a much higher-order filter (more coefficients) than IIR filters with comparable performance. Digital filter design involves the computation of filter coefficients to approximate the desired frequency response. The design process starts from the filter specification and ends in the implementation of the desired filter. A filter-design software package saves time when designing a filter quickly and supports the design of a quantized filter for a given word length.
