Enhancing Continuous Beam Angle Resolution for Next Generation Wireless Systems: A Multi-Stage Phase-Shifting Polyphase Filters Approach

Increasing user density and capacity in next-generation systems presents a need for fine beam angle resolution especially in the emerging upper mid-band <inline-formula> <tex-math notation="LaTeX">$7-24$ </tex-math></inline-formula> GHz frequency regime. This paper presents a scalable area- and energy-efficient quadrature generator targeted for beamforming receivers with a multi-stage phase-shifting polyphase filter providing continuous beam angle resolution. When complemented with vector modulation for coarse tuning, a phase range of 360° is achieved realizing a phase-shifter-less implementation leveraging slice-based receiver architecture and polyphase filters. Fabricated in 65nm CMOS, the phase-shifting polyphase filter occupies 0.003 mm2, consumes 0.25 mW, and achieves an Image Rejection Ratio >58 dB over the entire phase range. The quadrature generator is demonstrated with a proof-of-concept receiver array operating between 7.28-7.78 GHz consuming 37 mW per element occupying 1.26 mm2.