Computer aided-design of band-pass filters

Abstract

An efficient and versatile CAD tool for the design and synthesis of narrow band, band-pass microwave filters with generalized Chebyshev transfer function has been developed. The program allows the insertion of transfer function zeros at prescribed positions. Thus, it is suitable for asymmetric response or self-equalized filters. The location of the zeros can be optimized in order to comply with insertion loss and/or group delay specification masks. Subsequently, band-pass prototypes may be obtained with several topologies, namely canonical, in-line, cascaded triplets, cascaded quadruplets and combinations of them. A method based on gradient optimization that allows exact or approximate synthesis of filters is also available. The software is specially meant for the design of dielectric resonator filters with strict selectivity requirements. Some of its features are very well suited for predistortion techniques and easy tuning of these filters.