Compact and Low-Loss Phase Shifters and Multibit Phase Shifters Based on Inverted-E Topology

Abstract

This article proposes a novel inverted-E topology for the design of phase shifters and multibit phase shifters. The novel phase shifter consists of a <inline-formula> <tex-math notation= LaTeX >$50~\\Omega $ </tex-math></inline-formula> main transmission line (MTL) symmetrically loaded with equally spaced three open-/short-circuited stubs via P-I-N switching diodes. The stubs provide the needed susceptances to achieve a phase shift with large value range. Thanks to the design flexibility of the topology, 2^N-1 sets of stubs can share the same MTL, providing <inline-formula> <tex-math notation= LaTeX >$2^{n}$ </tex-math></inline-formula> phase states of an N-bit phase shifter. Design theory and performance analysis of the design variables are presented, followed by the analysis and simulation of four 22.5°, 45°, 90°, and 180° phase shifters. For validation and comparison, two typical 45° and 90° phase shifters and a 3-bit phase shifter, providing eight distinct phase states, have been fabricated and measured. The measured results show good agreement with analysis and simulation. In comparison to its traditional counterparts, the novel design yields a highly compact phase shifter because the separation between the loading elements on the MTL can be less than quarter wavelength, whereas low insertion loss is achieved because the diodes are loaded to the branches. In addition, multibit phase shifter in single unit can be realized with much shorter length and lower insertion loss.