A 28-GHz Phased-Array Receiver Front End With Dual-Vector Distributed Beamforming

Abstract

This paper presents a 28-GHz four-channel phased-array receiver in 130-nm SiGe BiCMOS technology for fifth-generation cellular application. The phased-array receiver employs scalar-only weighting functions within each receive path and then global quadrature power combining to realize beamforming. We discuss both the theory and nonidealities of this architecture and then circuit design details for our phased-array front-end prototype. Differential low-noise amplifiers and dual-vector variable-gain amplifiers are used to realize each front end in a compact area of 0.3 mm2. Across 4-b phase settings, each array element achieves 5.1–7 dB noise figure, −16.8 to −13.8 dBm input-referred 1-dB compression point, and −10.5 to −8.9 dBm input-referred third-order intercept point. The average gain per element is 10.5 dB at 29.7 GHz, whereas the 3-dB bandwidth is 24.5% (26.5–33.9 GHz). Root-mean-squared gain and phase errors are less than 0.6 dB and 5.4° across 28–32 GHz, respectively, and all four elements provide well-matched and well-isolated responses. Power consumption is 136 mW per element, equaling 546 mW for the four-element array.