Study On A Fast Analysis And Design Tool For LTCC Laminated Ridge Waveguide Bandpass Filters

With the rapid development of the wireless communication technology,people are increasingly demanding the miniaturization,light weight,and high reliability of microwave devices and systems.Low temperature co-fired ceramic(LTCC)technology is widely used in passive components.This paper focuses on a typical category of LTCC passive components-laminated ridge waveguide bandpass filters,which prove to possess many advantages,such as low loss,compact size and wide bandwidth.The analysis and design of such filters currently rely mainly on numerical simulation,and the efficiency is relatively low,since there exists no accurate formulations between electromagnetic characteristics and dimensional parameters of the filter.This paper studies the fast analysis and design tools for LTCC laminated ridge waveguide bandpass filters.Detailed contents are explicated as follows:1)The extraction methods of the electromagnetic characteristic parameters of the components of the filter(including LTCC laminated ridge waveguide and LTCC laminated ridge waveguide coupling section)are studied.For the former,the extraction methods of the characteristic parameters of transmission line,and the resonance characteristic parameters as a half-wavelength resonator are studied.For the latter,the extraction methods of the equivalent circuit parameters,inverter parameters and additional phase shift parameters as an inverter are studied.These parameter extraction methods are used in the creation of the database for the fast analysis and design tools.2)A fast analysis algorithm for LTCC laminated ridge waveguide bandpass filters is proposed.The transfer matrixes of the ridge waveguides and coupling sections required in the algorithm are directly calculated from the transmission line characteristic parameters and the equivalent circuit parameters,and these characteristic parameters are obtained by interpolation in the previously created database,thereby ensuring the efficiency of algorithm execution.The accuracy and efficiency of the proposed fast analysis algorithm are verified by an analysis example of a narrowband and a wideband bandpass filter.3)A fast design tool for LTCC laminated ridge waveguide bandpass filters is developed.This tool includes two parts:initial design module and the optimization design module.In the initial design module,the classical filter network synthesis method is used to obtain several initial designs of filters.The half-wavelength resonance characteristic parameters of the ridge waveguides,the inverter parameters and additional phase shift parameters of the coupling sections are all obtained by interpolation in the database.In the optimization design module,these initial designs are used as initial populations,and multiple iterations of the filter design are performed using the genetic algorithm.Finally,an optimal design of the filter is obtained.The validity of the proposed fast design tool is verified by a design example of a fifth-order bandpass filter.