A 26-GHz Vector Modulator in 130-nm SiGe BiCMOS Achieving Monotonic 10-b Phase Resolution Without Calibration

This paper presents a high-resolution (10-b) vevtor-modulator (VM) phase shifter (PS) in 130-nm SiGe BiCMOS targeting 5G applications at 26 GHz. It employs a Gilbert-cell RF core, the tail current of which is controlled by an 8-b low-power current-steering DAC and 2-b I/Q sign switches. The DAC includes an on-chip PTAT current reference with process compensation capabilities. A 2-stage RC polyphase filter (PPF) is used to generate the quadrature signals. Without any calibration or correction of PS control signals, the measured results demonstrate completely monotonic 210 phase states, covering the full 0-360° range without any dead zones or overlapping phase states. The worst case (maximum) phase difference between any adjacent states is 0.65°. The VM exhibits an average insertion loss of 0.5 dB at 26 GHz with a 3-dB BW of 8 GHz, an rms amplitude error of 0.2 dB, IP 1dB of 2 dBm, and 23 mW dc power dissipation. Potential applications are in RF beamforming and RF self-interference cancellation.