A Compact and Continuously Tunable 360° Phase Shifter Using Cascaded Transformer-Based 180° Reflection-Type and Switched-Type Phase-Shift-Cell

Abstract

This article presents a design method for compact and continuously tunable 360° phase shifter (PS). The proposed structure consists of a 180° reflection-type phase shifter (RTPS) cascaded with a 180° switched-type phase shifter (STPS). RTPS consists of a transformer-based 90° coupler and Γ-π reflection loads. STPS consists of a transformer and a single-pole double-throw (SPDT). For experimental verification, a compact and continuously tunable 360° PS with a center frequency of 1.5 GHz was designed and fabricated. From the measurement results, the proposed 360° PS provides a tunable phase shift range (PSR) of 0°–360°, with an the insertion loss (IL) of 2.85 ± 0.7 dB, which has a circuit size of 0.031 λg².