An 85-to-105 GHz Vector Modulator Phase Shifter Using. Optimized Passive Devices with <0.93dB/3.5° RMS Gain/Phase Error in 0.13-μm SiGe BiCMOS

This paper presents a W-band broadband vector-modulator phase shifter (VMPS) employing an optimized passive on-chip device including an in-phase/quadrature (I/Q) signal generator and a low-loss combiner. A novel hybrid coupler is proposed to generate high-precision, low-loss quadrature signals, while two optimized transformer-based baluns are designed to produce broadband differential I/Q signals across the target frequency range. To enhance gain, a modified Gilbert cell, serving as a variable gain amplifier (VGA), is integrated with the proposed low-loss folded combiner to achieve superior average gain. Designed in a 0.13-μm SiGe BiCMOS process, the phase shifter demonstrates full 360° coverage with 5.625° resolution over an 85–105 GHz bandwidth, achieving RMS amplitude and phase errors below 0.93 dB and 3.5°, respectively. The design exhibits a peak average gain of -2 dB at 94 GHz and 34-mW power consumption with a compact core area of 0.15 mm².