In this chapter, we first described a procedure by which a network function H(s) can be obtained when its magnitude function |H(jw)| is given. One key step is to factor a polynomial which may be of fairly high degree. The software MATLAB is suitable for this purpose. There are numerous other programs that can also be used.
Then we gave the closed-form formulas for poles of the Butterworth and Chebyshev lowpass filters. We also gave a qualitative description, using the conformal transformation, of how network functions for elliptic filters can be obtained. For this class of filters, we generally rely on tables or certain software for occasional needs [Su3]. Several tables for all three types of filters are given in Appendix A.
KeywordsLowpass Filter Group Delay Network Function Stop Band Filter Function
Unable to display preview. Download preview PDF.