Diagnosis of Coupled Resonator Bandpass Filters Using Vf and Optimization Method

Abstract

This paper presents a hybrid method combining a vector fitting (VF) and a global optimization for diagnosing coupled resonator bandpass filters. The method can extract coupling matrix from the measured or electromagnetically simulated admittance parameters (Y -parameters) of a narrow band coupled resonator bandpass filter with losses. The optimization method is used to remove the phase shift effects of the measured or the EM simulated Y -parameters caused by the loaded transmission lines at the input/output ports of a filter. VF is applied to determine the complex poles and residues of the Y -parameters without phase shift. The coupling matrix can be extracted (also called the filter diagnosis) by these complex poles and residues. The method can be used to computer-aided tuning (CAT) of a filter in the stage of this filter design and/or product process to accelerate its physical design.Three application examples illustrate the validity of the proposed method.

Extracting Coupling Matrix From Lossy Filters With Uneven-Qs Using Differential Evolution Optimization Technique

“…Once they are known, the complex CM representing the lossy filter can be obtain, and then the extracted S-parameters can be obtained using Eq. (15).…”

“…The unloaded Q factors are obtained by analytic method that the results are not accurate enough. Reference uses optimized technology to determine the phase shift, the optimal variables are reduced, and the method to extracting CM by VF after removing the phase shift will have some problems. The current optimization methods are focused on the genetic algorithm (GA), and does not take into account the other optimized methods.…”