Multifunction Reconfigurable Phase Shifter With Independent 360° Transmission and Reflection Phase Tuning for Multibit Reconfigurable Intelligent Surface

Abstract

This letter reports a 7-bit 360° multifunction reconfigurable phase shifter (RPS) with independently tuned transmission and reflection modes. The proposed RPS is a promising candidate for multibit reconfigurable intelligent surfaces (RISs) with high gain and full-space coverage. First, the novel topology and design method of the multifunction RPS are proposed in this letter for the first time. The proposed RPS can provide time-division independent 360° transmission and reflection phase tuning with a single shared reflection-type phase shifter topology. Second, in the transmission mode, a two-step phase extraction method is adopted, obtaining a 360° phase shift with low phase steps and a simplified process. The traversal states are reduced by (1– $2^{1 - n}$ ) $\times 100$ % for an n-bit varactor. Third, in the reflection mode, the equivalent topology in the reflection mode is enhanced to enable a 360° phase shift with moderate phase steps as well. Finally, our proof-of-concept RPS design is implemented in PCB technology. The proposed RPS exhibits a phase range of 369° with an insertion loss of $2.26~\pm ~0.74$ dB in transmission mode, and a phase range of 365° with an insertion loss of $3.07~\pm ~1.53$ dB in reflection mode at 2.45 GHz.