Miniaturized Distributed Marchand Balun Using Coupled Synthesized CPWs

A miniaturized distributed Marchand balun, composed of two unequal sections of coupled slow-wave synthesized coplanar waveguides, is developed in this letter. With the even odd mode analysis, the propagation characteristics of the coupled synthesized lines are analyzed. A simple phase compensation scheme, with unequal coupling sections, is proposed to compensate for the phase imbalance due to the non-zero connection line between the coupled-line sections. Without the need of surface-mounted capacitors, the proposed balun provides a comparable miniaturization capability but wider bandwidth when compared with its lumped-distributed counterparts. The circuit topology, design consideration, and simulated and experimental results are discussed thoroughly.