A Compact Broadband 180-Degree Phase Shifter Based On Coupled Transformer Structure

This paper presents a novel and compact design for a broadband 180-degree phase shifter, with a primary focus on improving bandwidth and minimizing chip area. The study explores the foundational principles underlying the generation of a 180-degree phase shift by positively and negatively connecting a transformer. The paper includes the derivation of the equivalent circuit for the coupled transformer through theoretical analysis. Furthermore, a comparative analysis is conducted between the conventional high-pass/low-pass topology and the proposed phase shifter. The simulation results showcase that the proposed phase shifter exhibits a smaller circuit footprint, decreased insertion loss, and consistent phase flatness across a broad bandwidth.