Equivalent Circuit and Electromagnetic Based CAD Tool for Dual-Mode Ku-Band Elliptic and Butterworth Filters

Recent drive in RF/microwave industries towards higher operating frequencies and complex designs, coupled with corporate pressures like manufacturability-driven design and time-to-market, demand advanced computer aided design (CAD) tools for microwave and millimeter-wave circuits. Filtering is a key operation in most high-frequency applications. Dual-mode filters are attractive since they reduce the need for number of resonators (or cavities) by a factor of two. Butterworth filters, in particular, provide a maximally flat response in the pass-band. In this paper, we present a CAD approach for design and tuning of dual-mode Ku-band filters. In the proposed approach, design and tuning are performed using an equivalent-circuit based in-house computer program and a full-wave EM solver. The approach is illustrated via design and tuning of a 14.5 GHz Butterworth filter