A Phase Shifter Based on Trans-Directional Coupler with DC Isolation of RF-Path and Control Circuit

Novel reflection type phase shifter schematic and design based on trans-directional coupler with DC isolation of RF-path and control circuit are proposed. The coupler is implemented as a 3-D vertically installed planar structure. Analog phase shifter prototype using GaAs varactor diodes operates over a 3.5 to 5.3 GHz (40
^%
) band and allows obtaining controllable phase shift of 0-65° with 0.15 dB amplitude variation at 4.5 GHz.