Toward efficient, reconfigurable, and compact beamforming for 5g millimeter-wave systems

Abstract

In this paper, we discuss architectures and integrated circuits for efficient, reconfigurable and compact millimeter-wave beamforming in silicon. First, we present techniques to improve peak and back-off power-added efficiency (PAE) of SiGe power amplifiers, demonstrated with a 28-GHz harmonic-tuned amplifier (+15.5 dBm output 1-dB compression point, 35% peak PAE, 11.5% PAE at 6-dB back-off) and a 60GHz Doherty amplifier (+17.1 dBm output 1-dB compression point, 23.7% peak PAE, 13% PAE at 6-dB back-off). Second, we present a dual-vector Doherty beamformer architecture which allows reconfiguration between an efficient Doherty mode (+16.7 dBm output 1-dB compression point and 7% PAE at 6-dB backoff) and a linear class-AB mode (+13 dBm output 1-dB compression point and 4.5% PAE at 6-dB back-off), demonstrated in SiGe at 60 GHz. Finally, we present a compact architecture for beamformers which employs dual-vector scaling functions within each element and then global combining and interpolation. This is demonstrated with a 28-GHz dual-vector receiver array in SiGe which requires only 0.3 mm2 for each receiver front-end.