A novel type of constant impedance traveling wave phase shifter for InP-based MMICs

The paper presents a novel type of externally controllable phase shifter based on periodic coplanar transmission lines consisting of Schottky contact (SCCPL) and coplanar sections on a passive substrate. The modeling of the devices is carried out by utilizing a four-pole representation of the underlying /spl pi/-sections. An optimized InP-InGaAs-InAlAs layer structure for the SCCPL is developed providing an external electronic control. Measured phase shifts up to 60/spl deg//mm at 20 GHz with a line impedance of 48/spl plusmn/1.2 /spl Omega/ agree well with theoretical calculations.