Research On Modeling Optimization And Design Method Of Marchand Balun

Marchand balun as passive devices,widely used in RF front-end circuit,is an important part of IOT wireless transceiver chip in agricultural field.In the design of Marchand balun,electromagnetic simulation usually require high performance computer and serious time-comsuming,especially in the condition of complex structure of balun substrate.In order to solve the problem of modeling establishment of optimization efficiency and bottleneck,this paper use theoretical analysis and extensive simulation to establish the correspondence between physical dimensions of coupled line and parameters of the model.In this paper,the analysis method of symmetric and asymmetric coupled line are discussed and the four port network are derived.Using the conclusion,the coupled line circuit model is established and parameter extraction is presented.After the detailed discussion of the process of model parameter extraction,large numbers of parameters were be fitted and analysis to find corresponding relationship between physical dimensions of the coupling line(Length, Width and Spacing)and model parameters.A series of corresponding equations then be establish. Using the equations, we can directly calculate the parameters of the model and largely reduce the EM simulation of coupled lines,thus can improve the efficiency of building of the model.Using the established circuit model of coupled lines,the model of Marchand balun was proposed,which can be used to simulate the performance of the device.Finally, the accuracy of the circuit model can be verified by the simulation and the Balun on PCB board.Also different structures and different processes were present to find out the the concrete method to optimize the performance of Marchand Balun.At the same time,investigating the influence of capacitive and inductive compensation on the performance of Marchand Balun,indirectly proved that the modified model can reflect the change of the circuit after adding compensated components.The model and parameter extraction method of Marchand balun is effective to speed up the design period.The test results show that the model has a high accuracy which provides a good reference for the actual design of balun.