A miniaturized lumped-distributed balun for modern wireless communication systems

The reduction in size of RF signal processing components is an important part of the miniaturization and cost reduction of wireless communication systems. A balun is a crucial component in most wireless communication systems. In this paper we describe research aimed at reducing the size and manufacturing complexity of printed baluns. A design utilizing distributed microstrip coupled lines and lumped capacitors is presented. The structure has the major advantage of being considerably smaller than the quarter-wavelength size of conventional "planar" baluns. This work is unique in that simulated results are presented which describe the effects and tradeoffs of changing important design parameters. The paper then describes performance-enhancing changes to the design. Excellent response characteristics for coupled circuit performance are shown to result.