A novel model for a planar wideband Marchand balun

A new lumped element model for conventional Marchand baluns is presented.Analyzed by the evenand odd-mode method,the equivalent equations are derived for λ/4 coupled lines.Based on the proposed 5th-order lumped equivalent circuit for λ/4 coupled lines,the self-inductance,mutual inductive coupling and the capacitance can be calculated according to the even- and odd-mode characteristic impedance,therefore,the model parameters of the balun can be easily gained from the derived equations.To verify the model,a GaAs monolithic wideband Marchand balun was implemented and tested.The EM simulation and experimental results show a good agreement with the model simulation.This model is available in a wide frequency range and makes the design procedure of the Marchand balun faster and easier.