Broadband monolithic left-handed coupled-lines incorporating interwoven capacitor and stacking inductor

This paper presents the designs of monolithic left-handed coupled lines to achieve the coupling bandwidth exceeding 213 GHz. The interwoven-capacitor and the stacking-inductor are applied to achieve lower cut-off frequency of left-handed transmission line without sacrificing the size of the unit cell. The complex propagation constant of the single transmission line is extracted from two-port scattering parameters to theoretically confirm the prediction. The prototypes of the coupled-line, fabricated by RF CMOS 0.13 um 1P8M technology, are characterized through the full-wave simulations and the on-wafer measurements. The complex propagation constants in even/odd mode, which are extracted from four-port scattering parameters, reveal that the coupling bandwidths of the two designs are 213 GHz, and 297 GHz, respectively.