A Compact Ka-Band Eight-Element Four-Beam Receiver for Low-Earth-Orbit Satellite Communications in 65-nm CMOS

This paper presents a Ka-band compact eight-element four-beam phased-array receiver to improve communication capacity for millimeter-wave satellite communications. To address the design challenge of the large area induced by the multibeam forming, the receiver utilizes a digital-assisted variable-gain phase shifting technique and an active combining scheme to enable compact implementation and facilitate array design. The receiver achieves a 360° phase shifting range with a 6-bit resolution and a 25-dB attenuation range with a 0.5-dB step. The measured root mean square (rms) phase and amplitude errors are 1.1° and 0.11 dB at 29.5 GHz, respectively. Each element achieves a gain of 26.7 dB, a minimum noise figure (NF) of 3.7 dB, and an input-referred 1-dB gain compression point (IP1dB) of −32.5 dBm. The proposed receiver demonstrates the state-of-the-art number of simultaneously reconfigurable beams with a compact size among millimeter-wave silicon-based beamformers.