A wideband 360° analog phase shifter design

This paper proposes a reflection-type wideband 360 deg analogue phase shifter. The phase shifter employs a branch-line coupler circuit to achieve a wideband operation and a varactor-diode circuit to achieve a wide phase-shift range. Analytical formulas are derived to optimize the parameters in the coupler circuit for wideband operation and reduced attenuation ripple, and in the varactor circuit to minimize the frequency dependency of the output phase. Simulation results using the Advanced Design Systems (ADS 2005A) show that the design has a wide bandwidth, wide phase shift range, and low attenuation ripple, and is highly linear across the operation bandwidth.