A novel tunable impedance transmission line for mm-waves applications

In this paper a novel tunable transmission line operating in V-band (57 GHz to 66 GHz) is presented. Designed in a 130 nm BiCMOS technology, the proposed structure explores ground plane switching to perform impedance tuning. It exhibits a 16 Ohms shift over characteristic impedance — equivalent to 30% of tuning range — with a Q-factor higher than 16 thanks to a shielding used in slow-waves transmission lines. Using this topology versus a classical 50 Ohms coplanar waveguide into a reconfigurable pi-type matching network with tunable stubs, it allows to cover around 100% more of impedances in the Smith Chart with a “2 dimensional” tuning.