Analysis and design of a high-performance planar Marchand balun

This paper presents an enhanced Marchand balun that offers excellent amplitude and phase balance performance. The enhanced Marchand balun is designed using compensated coupled lines. It employs capacitive compensation, a renowned technique for compensating the unequal even- and odd-mode phase velocities encountered in parallel-coupled microstrips. Analysis carried out in this study has proven that the finite directivity of coupled lines significantly affects the balun performance. The proposed capacitively-compensated Marchand balun is demonstrated at 2.1 GHz and has offered excellent results.