Performance analysis of optimum Chebyshev filters at microwave frequencies

Abstract

The paper suggests that optimum Chebyshev filters present an excellent choice for microwave filter design, as this approximation offers minimum return loss in the half-power passband, provides a maximum cutoff slope, and maintains low sensitivity in the passband. A comparative analysis is conducted with the chained-function filters to demonstrate the efficacy of this approximation, since chained-function filters also utilize Chebyshev polynomials to shape the filter’s characteristic function. The optimum Chebyshev filter, along with two chained-function filters, each of the sixth-degree, are realized, simulated, and compared as lowpass stepped impedance filters with a half-power passband of 1 GHz. After a detailed comparison, it is concluded that the optimum Chebyshev filter outperforms, or at least matches, the performance of the chained-function filters. This suggests that the optimum Chebyshev filter can effectively replace chained-function filters in all applications, offering a superior solution.