A Software Package for the Design of Band-Pass Microwave Generalized Chebyschev Filters with Symmetric or Asymmetric Amplitude Response and Equalized Group Delay

A software package for the synthesis of even and odd order equiripple band-pass filters, with arbitrary location of its transfer function zeros, giving symmetric or asymmetric amplitude response and equalized group delay, has been developed. Borland C + +® 3.1 compiler and LabWindows® 2.2.1 window system has been used. The program runs under MS-DOS, Windows 3.x and Windows 95 (DOS window). The program optimizes the position of the transfer function zeros in order to fulfill the insertion loss and group delay specification masks. The optimization procedure is done considering also possible losses. From the optimized S parameters, a semi-lumped low-pass prototype is synthesized. It may be transformed to different but equivalent topologies: canonical, in-line and so on. The corresponding semi-lumped band-pass filter is obtained from it, using the adequate frequency transformation. Then, the band-pass filter parameters are computed. An HP-Eesof Libra file may be obtained. Thus, the synthesized band-pass filter may be analyzed in order to check the corresponding `S11´ `S12´ and group delay against those synthesized by the software package. The actual band-pass filter may be constructed using a variety of microwave technologies (cavities, dielectric resonators, microstrip, etc.), depending on the concrete application, frequency band, and so on. The package is a unique compact CAD tool in which several design methods, optimization procedures, and analysis tools are combined. It provides quick and reliable designs in one of the most important microwave fields.