Optimization Synthesis Of Generalized Filter Components

With the rapid development of wireless communication,the complexity of wireless communication equipment and its performance requirements are constantly improving,it is faced with the requirements of miniaturization,high performance,multi-function and low cost.The performance of filters is directly related to the development of RF/microwave front-end circuits and miniaturization of the whole machine.Therefore,the method of filter synthesis has become a research hotspot of microwave filter devices in recent years.In this paper,the coupling matrix of the filter is obtained by optimization algorithm,the optimization algorithm combines global optimization algorithm(GA)with local optimization algorithm(Solvopt algorithm).The effectiveness of the algorithm is verified by a numerical example.The main contents are as follows:1.Study on Optimal Synthesis Theory of Cross-Coupled Resonator Filters,the limitations of the development of traditional filters and the advantages of cross-coupled resonator filters are described.The algebraic synthesis algorithm is used to synthesize the traditional cross-coupled resonator filters,and the optimization algorithm is used in this paper.The optimization algorithm does not need to revolve through the matrix and is not limited to a specific topology structure.The coupling matrix and load resistance are extracted by the optimization algorithm,and the effectiveness of the optimization algorithm is proved by numerical examples.2.The cross-coupling of non-adjacent resonators can improve the out-of-band selectivity of filters.However,the error of high-order filters in simulation and processing can only be satisfied by later tuning.In order to reduce the influence of errors on the performance of filters,a cascaded cell module is proposed to construct the filters.The resonators are connected by NRN.Using this technique,a modularly designed filter of order N can generate up to N transmission zeros without directly coupling the source to the load.3.The traditional synthesis method only considers the normalization of filter port impedance,considering its cascade with RF front-end device(antenna/ amplifier),impedance matching structure will increase the volume of RF front-end.A synthesis technique of cross-coupled filters with frequency-varying coupling coefficients for arbitrary port impedance is proposed,this method can make the filter cascade with other devices without impedance matching structure.Cross-coupled filters with frequency-varying coupling coefficients can achieve more finite transmission zeros with the same order as traditional cross-coupled filters,the size of RF front-end can be effectively reduced.4.Traditional methods to realize finite transmission zeros are: cross-coupled filter synthesis technology and pole extraction technology.It is difficult to tune or produce fictitious zeros by using a single technology.Combining the advantages of cross-coupled filter synthesis technology and pole extraction technology,the synthesis technique of hybrid topological filter is proposed.The design flexibility of the filter is improved without additional auxiliary resonators and a large number of matrix rotation changes.