Monolithic GaAs-InGaP HBT balanced vector modulators for millimeter-wave wireless systems

This paper describes the design and performance of millimeter-wave balanced vector modulators employing the Marconi HBT MMIC technology. Two versions have been fabricated for operation at 38 GHz; the first employs normal Lange couplers whilst the second employs miniaturised microstrip couplers, which reduce the MMIC chip area by more than 40%. With a simple bias calibration technique the circuits achieve near-perfect constellations with negligible amplitude and phase errors over a wide bandwidth.