Compact ultra-wideband stacked-spiral-coupled balun using center-tapped float-shield and port-coupled compensation line

A compact on-chip stacked-spiral-coupled balun is proposed in this paper based on the center-tapped float-shield and port-coupled compensation line. The ultra-wideband (UWB) operation and miniaturized size are simultaneously employed using the stacked-spiral-coupled scheme. Meanwhile, the center-tapped float-shield and port-coupled compensation line are introduced to achieve the low inband amplitude- and phase-balances with excellence responses, respectively. Then, the proposed balun operated over the bandwidth (i.e., 11.5-46.5 GHz) is implemented and fabricated using IBM 0.13 um SiGe process. The measured amplitude- and phase-imbalances of the on-chip balun are ±1 dB and ±1.31°, respectively, which exhibit strong merits for the practical UWB point-to-point communication application.