Design high performance Marchand balun with step-impedance transmission lines compensated parallel-coupled lines

This paper presents a novel simple technique to improve amplitude and phase balance of the microstrip Marchand balun. This is readily achieved by using the SITL compensated coupled lines in cooperating with a series capacitor to well match the unbalanced port. The technique evidently shows the improvement of amplitude and phase balance and good input ports return loss. The proposed balun can be used in many wireless and microwave systems.