A 1-4 GHz 4x4 MIMO receiver with 4 reconfigurable orthogonal beams for analog interference rejection

A highly reconfigurable multi-beam MIMO receiver with 4 RF inputs and 4 outputs is proposed, allowing for digital MIMO but also analog interference rejection by spatial notch filtering through 4 reconfigurable orthogonal beams. A segmented constant-Gm vector modulator with improved interference tolerance and RF frequency range is proposed, allowing current-domain beamforming before I-V conversion by a transimpedance amplifier. A 1-4 GHz 22 nm FD-SOI prototype chip achieves >29 spatial notch suppression for in-band interference signals. In the notches, an IIP3 of +17 dBm and in-band B1dB of-12 dBm is achieved at 44.5 dB gain. Sub-3dB system noise figure is achievable in the corner points of vector modulator constellation. On the circle points, noise figure degrades about 2.5 dB. However, in-band, in-notch B1dB and IIP3 improve by 32dB and 43dB, respectively. The chip of 0.52 mm ² active area consumes 75-115mW at an LO-frequency of 1-4 GHz from a 0.8V supply.