2 × 4 VGA-Less Bidirectional Dual-Polarization 28 GHz Beamformer in 130-nm SiGe BiCMOS

This letter presents a dual-polarization beamformer chip for fifth-generation (5G) applications. The chip leverages a vector-sum phase shifter (VSPS) approach and single-ended design, allowing a reduced control circuitry complexity. The use of the VSPS translates in both phase shift and gain control, as shown in the system analysis. This beamformer is suitable for four dual-polarized antennas, achieving high gain control for each element. The performance can be summarized as a 1-dB compression point of 11dBm, while having an rms phase and amplitude error lower than 0.5° and 0.4 dB, respectively, at the maximum constant magnitude gain circle. Moreover, it is shown that the design can afford tapering despite relying only on the VSPS for gain control.