A four-antenna receiver in 90-nm CMOS for beamforming and spatial diversity

A fully integrated four-channel multi-antenna receiver intended for beamforming and spatial diversity applications is presented. It can also be used as a low-power area-efficient range extender for spatially multiplexed multi-antenna systems that are poised to become mainstream in the near future. Implemented in a 90-nm CMOS technology, each channel weights its input signal by a complex weight with full 360° phase shift programmability using vector combinations of variable-gain amplifiers, thus obviating the need for expensive phase shifters. The chip consumes 140 mW from a single 1.4-V supply and achieves 12 dB of array gain with all four channels activated and >20 dB direction-of-arrival-dependent interference rejection.