Wideband 60 GHz SiGe-BiCMOS vector modulator for ultra-high-datarate wireless transmitters

This paper presents the design and characterization of a vector quadrature modulator integrated circuit, fabricated in a 0.25 μm SiGe BiCMOS technology for use in a QPSK wireless transmission system at 60 GHz. The approach chosen for narrowband quadrature generation allows the integration on a 0.98 mm×0.88 mm area, significantly smaller than other reported mm-wave quadrature modulator ICs. The circuit consists of two active double-balanced mixers and a network of transmission lines, whose impedances and lengths are designed to provide simultaneously quadrature differential signals and power matching to 50 Ω for the high-frequency ports of the mixers. On-wafer characterization of the modulator showed an amplitude error of only 0.3 dB and a phase error of 20°, suitable for single-carrier QPSK communications. For optimal operation, the circuit requires -3 dBm of carrier power and 16 mA of bias current from a 3 V supply.