Louis Gabello


This thesis deals with the design of filters in the frequency domain. The intention of the thesis is to present an overview of the concepts of filter design along with two significant developments: a comprehensive filter design computer program and the theoretical development of an Nth order elliptic filter design procedure. The overview is presented in a fashion which accents the filter design process. The topics discussed include defining the attenuation requirements, normalization, determining the poles and zeros, denormalization and implementation. For each of these topics the text ad dresses the fundamental filter types (low pass through band stop). Within the topic of determining the poles and zeros, three classical approximations are discussed: the Butterworth, Chebyshev and elliptic function. The overview is concluded by illustrating selected methods of implementing the basic filter types using infinite gain multiple feedback (IGMF) active filters. The second major portion of the thesis discusses the structure, use and results of a computer program called FILTER. The program is very extensive and encompasses all the design processes developed within the thesis. The user of the program experiences an interactive session where the design of the filter is guided from parameter entries through the response evaluation and finally the determination of component values for each stage of the active filter. Complete examples are given. Included within the program is an algorithm for determining the transfer function of an Nth order elliptic function filter. The development of the theory and the resulting design procedure are presented in the appendices. The elliptic theory and procedure represent an important result of the thesis effort. The significance of this development stems from the fact that methods of elliptic filter design have previously been too disseminated in the literature or inconclusive for an Nth order design approach. Included in this development is a rapidly converging method of determining the precise value of the elliptic sine function. This function is an essential part of the elliptic design process.

Library of Congress Subject Headings

Electric filters, Active

Publication Date


Document Type


Department, Program, or Center

Electrical Engineering (KGCOE)


Salem, Edward

Advisor/Committee Member

Tseng, Fung


Note: imported from RIT’s Digital Media Library running on DSpace to RIT Scholar Works in December 2013.

Physical copy available from RIT's Wallace Library at TK7872.F5 G23


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