Geometric Analysis and Systematic Design of Reflective-Type Phase Shifters with Wide Bandwidth and Low Phase Error

This article presents a visualized design method for reflective-type phase shifters (RTPSs) with wide bandwidth and low phase shifter. In this design, the concept of the phase slope circle, combined with a geometric method, is proposed to address the key issue of large phase error in RTPS. This method can directly evaluate the phase shift range (PSR) and phase deviation with respect to the varactor capacitance Cv. When its trajectory falls on the equal-phase-slope circle, low phase error can be achieved, and vice versa. We systematically analyze the existing reflective loads, including the capacitive, single resonated and multiple resonated loads, and explicitly illustrate their limitations. To achieve a large PSR and low phase error, a new reflective load consisting of mixed lumped and distributed resonators are proposed, which can reduce the phase error by more than 10 times under the same PSR and bandwidth as compared with the existing designs. To validate the design concept, a prototype of proposed 180° wideband RTPS was designed and tested.