Low-Loss Tunable-Phase Transmission Line Couplers -A Comparative Study

RF systems often suffer from the undesired phase shift of the input signal when operated over a wideband due to the inherent behavior of sub-circuits. A compact low-loss transmission line whose phase can be adjusted depending on the bias applied to a common-source amplifier in the coupled path is presented in this paper. Two active couplers with the same transistor size, different insertion phase, and sub-degree phase tunability are comparatively studied with previously known techniques. The simulations are carried out using 22nm FDSOI PDK.