Dual-vector phase rotator for Doherty beamformers

A 28-GHz dual-vector phase rotator is introduced, having the capability of generating two quadrature output signals that track one another in phase. The 4-bit dual-vector rotator was implemented in IBM 0.12-μm SiGe BiCMOS technology and achieves full 360o phase shifting, RMS phase and amplitude errors of <; 5 degrees and <; 0.8 dB, respectively for both output vectors, and 10-12 dB of gain. Output 1-dB compression points for both quadrature outputs is -6.5 to -4.4 dBm, suitable for directly driving a Doherty amplifier in a 28-GHz beamformer.