Design of Chebyshev Filters with Flat Group-Delay Characteristics

In this paper, a method for designing Chebyshev filters having flat group-delay characteristics in the main part of the passband is presented. From the general approximation theory, a method for obtaining the transfer function of Chebyshev filters with complex transmission zeros is derived, which are so determined that the group-delay characteristics may be flat in the main part of the passband. A new theory of cascade synthesis, which is an extension of Belevitch´s cycle, and an extended bisection theorem are introduced. By the applications of these results, Chebyshev filters with flat group delay can be realized. A practical design example is also included.