Design Of Directional Coupler Based On Thin Film Integrated Technology

In the high-speed development of system-level packaging technology,thin film integration technology has been widely concerned as a new technology with unlimited potential.Thin film integrated technology passive devices(Thin Film Integrated Passive Device)can realize resistors,inductors,capacitors,etc.on semiconductor dielectric substrates.The directional coupler based on thin film integration technology designed in this thesis has the characteristics of small area and wide bandwidth,which can greatly improve the performance of the whole RF circuit.In this thesis,we firstly analyze the planar spiral structure inductance and high-density plate capacitance on the GaAs dielectric substrate to obtain the best performance capacitance and inductance model.Using these models,a single π-type lumped parameter branch line directional coupler is designed,which realizes miniaturization(1.0mm*0.6mm)and then replaces the singleπ-type equivalent circuit by adopting cascaded π-type equivalent circuit.This new lumped-parameters directional coupler's performance is highly consistent with the distribution parameters directional coupler's performance and have a certain increase in bandwidth.Then,by increasing the number of branch lines to realize the wideband of the directional coupler,a lumped parameter four branch-line directional coupler is designed,and the bandwidth reaches to 30%.Finally,the thesis also analyzes and discusses the design of directional couplers with high-pass filtering characteristics.In this thesis,the directional coupler is miniaturized by using lumped elements,and the directional coupler is widened by increasing the number of branch lines.Through the advantages of thin film integration technology and lumped parameter element combination,the surge of model volume brought by the increase of branch lines has been successfully solved.The directional coupler designed in this thesis verifies the correctness of the design through the consistency of the AWR circuit simulation software and the HFSS three-dimensional electromagnetic simulation.