A Universal Reference Line-Based Differential Phase Shifter Structure With Simple Design Formulas

Abstract

The conventional differential phase shifter configurations usually require different reference lines to provide constant phase shifts over a certain bandwidth. This results in high design complexity, especially for the multiway and poly-phase applications. To solve this problem effectively, a new differential phase shifter configuration based on the parallel stubs loaded transmission line is proposed. The phase of different main lines in the proposed structure can be easily aligned with that of the same reference line by simply changing the position of the loading stubs, which has a linear relationship with the desired phase shift. The new phase aligning approach and the universal reference line bring about simplicity in design and implementation. For demonstration purposes, a group of differential phase shifters is designed, fabricated, and measured. The corresponding constant phase shifts (from 45° to 135° with a step of 15°) are obtained between the main lines and the reference line, over a bandwidth of 55.6% with small insertion loss and phase deviation.