LH phase shifter using ferroelectric varactors

A tunable left handed (LH) transmission line used as continuously tunable phase shifter is presented. Using varactors based on barium-strontium-titanate (BST) thick films, a figure of merit FoM = 29deg /dB has been measured at 2.8 GHz. The bandwidth of the realized circuit using 3 unit cells reached 10%. The agreement of the presented result from simulation and measurement is good, the differences can be explained by tolerances of the used components. Additionally the simulations of a 180deg phase shifter based on the same components for the unit cell is presented. Simulated results of this phase shifter shows a bandwidth of 27% and a FoM
_max
= 31.5deg /dB