Design of Novel Ultra-Wideband Bandpass Filter with High Selectivity and Wide Stop Band and Optimizing it with Neuro-Genetic Method

This paper develops a novel ultra-wideband bandpass filter with high selectivity, deep stop band and compact size. By linking a broadband bandstop filter at two sides with two feed lines via interdigital coupled lines with enhanced coupling degree, an initial ultra-wideband bandpass filter is created. In this filter, all undesired pass bands are rejected by broadband bandstop filter embedded in middle of ultra-wideband filter. Then, stepped impedance open stubs are used for realizing transmission zeros in pass band edges to increase selectivity. Finally, a neuro-genetic method is applied for optimizing of proposed ultra-wideband bandpass filter. For this task, first a nonlinear relation is established between the input (layout parameters) and output (electrical responses) data by using neural network. Then, genetic algorithm is used in conjunction with neural network model for optimizing the ultra-wideband bandpass filter parameters. The designed filter was fabricated and measured that showed good characteristics including deep stop band and very high pass band selectivity.