A 28-GHz 4-channel dual-vector receiver phased array in SiGe BiCMOS technology

This paper presents a 28-GHz four-channel phased-array receiver in 120-nm SiGe BiCMOS technology for 5G cellular application. The phased-array receiver employs scalar-only weighting functions within each front-end and then global quadrature power combining to realize beamforming. Differential LNAs and dual-vector variable-gain amplifiers are used to realize each front-end with compact area. Each front-end achieves 5.1 to 7 dB noise figure, -16.8 to -13.8 dBm input compression point, -10.5 to -8.9 dBm input third-order intercept point across 4-bit phase settings and a 3-dB bandwidth of 26.5 to 33.9GHz, while consuming 136 mW per element. RMS gain and phase errors are <; 0.6 dB and <; 5.4° at 28-32 GHz respectively, and all four elements reveal well-matched responses.

I. Introduction

There is an ever-growing need to support faster data rates in future cellular networks and this need has the potential to be met by shifting toward millimeter-wave frequencies (20–100 GHz). In particular, the 28-GHz frequency band is a prime candidate for 5G networks, due to suitable bandwidth, favorable channel characteristics, and the ability to realize power-efficient high-performance hardware in silicon. Link budgets for 28 GHz suggest moderate beamforming for handsets and stronger beamforming at the basestation. As a result, wide-bandwidth, low-area, and scalable phased-array architectures are required for future 28-GHz systems. In this work, we present a dual-vector 28-GHz receive beamformer which employs scalar-only weighting functions within each front-end and global quadrature combining to realize beamforming. Such scalar front ends can be both area-efficient and wide bandwidth. We demonstrate our concept with the realization of a four-element phased-array receive beamformer in SiGe BiCMOS operating at 28 GHz.