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 2
¹⁰
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.