Circuit model extraction for computer-aided tuning of a coupled-resonator diplexer

This paper introduces an analytical method for extracting the circuit model of a coupled-resonator diplexer from its frequency domain response. The method is based on a novel model-based vector fitting technique, in which not only the number of poles but also the number of zeros can be stipulated. The proposed method has been verified to be robust and accurate in dealing with noise contaminated measurement data of a diplexer. The tuning process of a typical coaxial resonator diplexer is used to illustrate the effectiveness of the method for computer-aided tuning (CAT) of a diplexer. The new method can facilitate the design and production of various coupled-resonator diplexers and can greatly benefit the wireless industry.