MATLAB Based Digital IIR Filter Design

a fundamental aspect of signal processing is filtering. Filtering involves the manipulation of the spectrum of a signal by passing or blocking certain portions of the spectrum, depending on the frequency of those portions. In this paper, Digital filters are designed using frequency specifications. Matlab provides different options for digital filter design, which includes function, calls to filter algorithms and a graphical user interface called Sptool. A variety of filter design algorithms are available in Matlab for both IIR and FIR filters. This paper discusses the different options in Matlab to design digital IIR filter. Four types of IIR filters are studied, Butterworth, Chebyshev I, Chebyshev II and Elliptic. Results obtained are plots of magnitude resp type of filter. Results show that the graphical user interface Sptool is a quicker and simpler option than the option of making function calls to the filter algorithms. Results are also co of MATLAB. Digital filtering is one of the most powerful tools of DSP implemented on DSP processor or in software. In both the interactive software, such as MATLAB, it is now possible to place more emphasis on learning new and difficult concepts than on programming algorithms. Interesting practical examples can be discussed, a be explored. MATLAB is a high performance language for technical computing. It integrates Computation, Visualization and programming in an easy to use environment. Digital IIR filters have been derived from their analog counterparts. Classical prototype analog filters are Butterworth, Chebyshev I, Chebyshev II and Elliptic. Parameters required designing IIR filters are sampling frequency, Pass frequency, Pass band ripples and Stop impulse response and order of the filter can be generated. Basic prototype IIR filters are of four types. First is Butterworth filter, whose magnitude response is maximally flat from Ω = 0 to Ω = ∞. types, Chebyshev I and Chebyshev II. The Chebyshev Type I filter minimizes the absolute difference between the ideal and actual frequency response over the band. Stop band response is maximally flat. The transition from pass Butterworth filter. between the ideal and actual frequency response over the entire the stop band. Pass band response is maximally flat. Elliptic filters ar They generally meet filter requirements with the lowest order of any supported filter type. Given a filter order band ripple Rp in decibels, and at . Magnitude response of these classical IIR filters is shown in following figures1, 2, 3, and 4 respectively. www.ijecse.org Based Digital IIR Filter Design Samarjeet Singh , Uma Sharma 2 Engineering BBDIT, Ghaziabad. 1 [email protected] 2 [email protected] onse, phase response, impulse response and pole mpared with the standard filter design tool i.e. FDA tool