$W$ -Band (92–100 GHz) Phased-Array Receive Channel With Quadrature-Hybrid-Based Vector Modulator

This paper presents a W-band (92-100 GHz) phased array receive channel adopting a power domain vector modulator (VM), which utilizes a 90° hybrid-coupler-based phase interpolator. The quadrature hybrid leverages its inherent functions of quadrature phase splitting and power combining to interpolate phases by combining the weighted signals from variable gain amplifiers in the power domain. Compared with prior active VMs, in the proposed VM, the phases are synthesized in a pure passive network with a matched impedance, less vulnerable to circuit nonlinearity. The distributed 90°-hybrid coupler offers a wideband operation of quadrature phasing and phase interpolation, resulting in a low phase error over the W-band. The measured VM peak-to-peak gain variation for all 5-bit phase states is 7.7-11 dB at the expense of 31-mW dc power from 2.2-V supply voltage. The measured rms gain error is <;1.6 dB over 93-108 GHz and the rms phase error is <;1.5° at 94 GHz. The output P
_-1dB
is -4 dBm at 94 GHz at the highest gain state. In the receive channel employing the 90°-hybrid-based VM, the peak-to-peak gain variation is 23-26 dB with 9.3-11-dB NF at the expense of 50-mW dc power from 2.2-V supply voltage. The measured input P
_-1dB
is -26 dBm. The chip size of the receive channel, implemented in 0.13-μm SiGe BiCMOS process, is 1.65 × 0.55 mm
²
.